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VAN NOSTRAND'S

ECLECTIC

Engineering Magazine.

VOLUME XII.

JANUARY-JUNE,

1875.

NEW YORK:

T>. VAN NO STRAND, PUBLISHER,

23 Murray Street and 27 Warren Street (up stairs).

1875 .

&&,6/9-

I

V3

CONTENTS

VOL. XII.

Page.

Academy, Paris 255

Aerial bridge 475

Aeronautics 540

Aggressive Torpedoes 1

Alloys, white 179

American association • 473

American association of iron

andsteel 282

American cartography 433

American car wheel3 for English

railways 378

American Institute of mining

engineers 282

American society of civil engi- neers 282,561

American transit campaign 370

American v. English bridges .... 202

Analysis of Heaton metal 90, 185

Appliances for enabling persons

to breathe in dense smoke 426

Applications of the Gyroscope. . 360

Arches, skew 97, 193, 289

Architects, Institute of British. . 376 Architectural practice, British

and American 132

Architecture, Queen Anne style

Of 59

Arsenal, Brazilian 477

Artillery, heavy 511

Artillery, German 477

Asphalt and concrete in their ap- plications to road-making

and building 526

Association, American 473

Association, American iron and

•ateel 282

Association of Foremen Me- chanics •. 191

Axis, Neutral, position of 365

Axles, railwav 321

Bessemer and Siemens — Martin

Steel 473

Bessemer Channel steamer 296

Bessemer Saloon "Gyroscopic"

apparatus' 120

Blast furnace, use of Slag in 401

Blast furnace, improvements in. 415 Blast furnaces, smelting of iron

in 461

Block system for railways 332

Boiler evaporation 374

Boiler explosions 340

Boilers, feed water in 283

Boston Society of Civil Engin- eers 561

Book Notices :

Andre, G. G. The Draughts- man's handbook of plan and map drawing ; includ- ing instructions for the pre- paration of engineering, architectural, and mechan- ical drawings 3S2

Angell, Arthur. Butter, its analysis 565

Angell, J. Elements of mag- netism and electricity 287

Page. Book Notices :

Atkinson, J. J. A practical treatise on the gases met with in coal mines 286

Bedford, Com. v. G. D. Sail- ors' pocket-book 566

Blake, W. P. Ceramic Art, a report < n pottery, por- celain, tiles, terra-cotta, and brick 286,382

Brush, G. J. Manual of de- terminative mineralogy, with an introduction to blow-pipe analysis 190

Carpenter, W. B. The Mi- croscope and its revela- tions 287

Chief Engineer's report of the improvemet of navi- gation of the St. Law- rence river 478

Church, A. H. Color 190

Collins, J. H. Principles of metal mining 286

Committee of the American society of civil engineers : rapid transit and termi- nal freight facilities 478

Committee of the British as- sociation ; notes and que- ries on anthropology 287

Corps of royal engineers ; professional papers 286

Croll, James. Climate and time 566

Danby, T. W. Guide to de- termination of minerals. . 569

De Larrepont, H. Les Sor- piles 94

Dislere, P. Les Croiseurs, La Guerre de course 477

Dixon, Thomas. Practical millwrights' ready reck- oner 565

Douglass, J. C. A manual of telegraph construction 287

Douglas, Professor Silas H. Qualitative analysis 566

Downing, S. Elements of practical construction for the use of students in en- gineering and architec- ture 479

Dredge, James. Eecord of Vienna Exposition 566

Drewar, A. Origin of crea- tion or the science of mat- ter and force 287

Eassie, P. B. Wood and its uses 477

Evers, H. A handbook of applied mechanics 190

Flemming,H. Narrow gauge railways in America 477

Forney, M. N. Catechism of the locomotive 287

Foye, James C. Determina- tion of Minerals 565

Page Book Notices :

Fraser, S. R. Origin of crea- tion, or the science of

matter and force 28T

Greene, C. E. Graphical method for the analysis

of bridge trusses 95, 383

Greenwood, W. H. A man- ual of metallurgy 383

Grover, J. W. Iron and timber railway super- structures 567

Hammond, A. The rudi- ments of practical brick- laying 565

Heath, D. Elementary ex- position on the doctrine

of energy 94

Hersehel, (J. Continuous re- volving draw-bridges 477

Hozean, Louis. Guide prac-

tique de telegraphie 567

Janes, John. Handrailing.. 566 Knight, E. H. American

mechanical dictionary . . 478 Mayer, A. M. The earth a

great magnet 286

Mtore, R. The artisan's

guide 568

Naval Institute Proceedings 565 Neville, John, C.E. Hydraul- ic tables 567

Noble, W. H. Useful tables 566 North, Oliver. The practi- cal assayer 568

Page, D. Geology in its re- lations to the Arts and

manufactures 2S8, 384

Payne, J. Practical solid geometry, or orthograph- ic projection . . 94

Pichault, S. Diagramma-

graphic 477

Plympton, G. W. The blow pipe ; a guide to its use in the determination of salts

and minerals 189

Prescott, H. B. Chemical examina ion of alcoholic

liquors 28<>

Prescott, A. B. Outlines of proximate organic analy- sis for the identification, separation, and quantita- tive determination of the more commonly occurr- ing compounds. .'..25, 190, 479 Rambosson, J. Astronomy. 477 Reed, Wm. H. Reed's head- light 566

Reese, J. J. Manual of tox- icology 190

Riddell, R. Mechanics' ge- ometry 94

Rig;.1, Arthur. Easy intro- duction to chemistry 565

Ross, O. C. D. Air as a fuel 287

Rutley, F. Mineralogy 190

Seton, Maj.-Gen. Sir Thos. Manual of wood carving. 566

il

i

Page. Book Notices :

Stat* engineer and surveyor of the state of New York ; Report on the railroads of

the state 477

Smiles, Samuel. The lives

of the engineers 565

Twisden, J. F. First lessons

in theoretical mechanics.. 383

Tyndall, J. .Scientific ad- dresses 286

Warren, S. E. Elements of

descriptive geometry 477

Warren, S. E. Elements of machine construction and

drawing 478

Watson, Prof. Course on descriptive geometry, for the use of colleges, and

scientific schools 94

Wellington. A. M. Compu- tative from diagrams of

railway earthwork 94

Willis, G. H. Commercial

short-hand 94

Wilson, J. W. Hints to

young engineers 190

Brass, polish on 263

Breathing in dense smoke, ap- paratus for 426

Brick and marble in the middle

ages 297

Bridge, Aerial 475

Bridge at St. Louis 379, 475

Bridge cylinders, iron 475

Bridg.es, American and English. 202 British and American architec- tural practice 132

British architects, institute of.. 376

British blast furnaces 377

Bronze, strength of 259

Bronzes, mechanical properties

of 12

Bronzes , new phosphor 91

Bronze steel 514

Cable telegraph 172

Canal tonnage 253

Cannon, Hotchkiss' revolving.. 224

Carthography, American 433

Car wheels, American. 378

Castings, smooth and brilliant.. 282

Channel tunnel 284

Channel tunnel, ventilation of. . 417 Channel steamer, the Bessemer. 296 Changes in iron by action of hy- drogen 502

Circular iron clads of Russia 492

Chinese coal fields 229

Chinese ironworks and collier- ies 377

Civil engineers, institution of

184, 376

Coal fields of China 229

Coal mines, gases in 17

Coals, mixing slacks of 204

Coke, mixing slacks of • 204

Collieries in China 377

Conversion of motion 313

Copper, polish on 263

Cotton gunpowder 305, 446

Cranes, foundry 270

Danube Improvements 563

Death, time of 339

Diamond, rock-boring drill 44

Dissipation of energv 519

Docks, tubular floating 28

Drainage of St. Petersburg 93

Drawing, Geometry and Color ;

as taught in Hindoostan . . 256

Dredging for amber 480

Earth measurements 236

Economic use of blast furnace

slag 401

Economical limits to the use of

rolled girders 234

Education, technical 260

Efficiency of furnaces burning

wet fuel 81, 123

CONTENTS.

Page.

Emery 472

Enamelling process 288

Energy, dissipation of 519

Engine, fire 304

Engineering in the East 153

Engineering, mechanical 173

Engineering process 113

Engineering, sanitary 356

Engineering work in Portugal . . 475 Engineers, American Institute

of mining 282

Engineers, American Society of

civil 282, 561

Engineers, Institution of civil

184, 376

Engineers, railway for India 188

Engineers, society of 89, 376

English • and American transit

campaigns 370

English and American bridges.. 202

Equivalent, mechanical, of heat. 80

Etchingiron 112

European railway construction. 205

European lighthouses 517

Expansion, heat absorbed by. . . 207

Expansion of Ebonite 321

Experiments on safety-valves.. 308

Explosions, boiler 340

Explosives, researches on 95

Eye-bars, heads of 8

Fire Engine.... 804

Fluxes for steel 186

Foundry cranes 270

French Navy 382

Friction of air in mines 209

Fuel in furnaces, economy of. . . 185 Fuel, furnaces burning wet... 81, 123

Fuel locomotive 379

Fuel, oil 328

Fuel saving 362

Furnace, blast 401

Fur nances, blast 415

Furnaces, Bntish blast 377

Furnaces, burning wet fuel. . .81, 123

Furnaces, economy of fuel in. . . 185 Furnaces, smelting of iron in

blast 461

Future of wages and of iron .... 3

French Manufactures 570

Gas, carbonic acid as a motive

power 192

Gases in coal mines 17

Gauge, narrow, in Switzerland. 206

Geographical society of Paris . . . 255

Girders, rolled 234

"Graphical Statics," new meth- od of 161, 274, 322, 885

Graphics 529

Gun, fog 285

Gunpowder, application of ther-

mo-chemicals to 232

Gunpowder, cotton 305, 446

Guns, improvement of heavy . . 381

Gyroscope, applications of 360

Harbor at Dover 188

Heat absorbed by expansion 207

Heat, mechanical equivalent of. 80

Heavy artillery 511

Helical pump 8S

Hotchkiss revolving cannon 224

Hydrogen and acids, effects of,

on iron 502

Ice boat and fire engine 304

Improvement in blast furnaces.. 415

Incombustible wood 366

Institute of British architects . . 376

Institute of mining engineers . . 282 Institution of civil engineers 184, 376

Iron and steel manufacture 300

Iron and steel production of

France 409

Iron and the smith 142

Iron association 282

Iron bridge cylinders 475

Iron, calcination of native ox-

idesof 185

Iron, cementation of 187

Iron, electro-deposit on of 186

Page.

Iron, etching on 112

Iron, future of . , 3

Iron heaters, system of making

90, 185

Iron manufacture 283

Iron market, Siberian 9©

Iron and stee1 wire 288

Iron, passivity of 258

Iron piers 182

Iron, silicon in pig 180

Iron ships, preservation of 93

Iron, smelting of 461

Iron, technology of 439

iron wire, effect of acid on 303

Ironworks in China 37T

Iron, wrought 362

Iron,cha ges in by action of hy- drogen 502

Iron clads of Russia 492

Irrigation, theory of 435

Japanese navy 9*

Lifeboat, New 564

Life Raft, Thompson's 564

Li ghtning conductors 208

Lighthouses, European 517

Locomotive fuel 379

Magnetic variations 95

Mann, Geo. H. Obituary notice

of 96

Manufacture of iron and steel

283. 300 Manufacture of pebble-powder.452,549

No. 2 545,549

Manufacture of steel 186, 300, 377

Manufacture of steel rails 264

Marble of the middle ages 297

Mechanical engineering 173

Mechanical equivalent of the

keatunit 80

Mechanical properties of bron- zes 12

Metals, coloration of 191

Meteorology, nautical . . 72

Metrological society 16

Mining engineers, institute of

American „ 282

Mineral resource of Bolivia 230

Mines, friction of- air in 209

Mines, gases in 17

Mines, ventilation of 17

Modules 40

Monitor, trial of a 382

Monument to Frederic Sauvage. 108

Motion, conversion of 313

Motive power, hydro-thermic. . . 471 Motors of the Vienna Exhibi- tion.... 343

Murphy, John W. Obituary no- tice of 96

Narrow gauge in Switzerland . . 206 Narrow gauge railways of Eu- rope 61

Nautical Meteorology 72

Navy, French 382

Navy, Japanese 93

New Method of "Graphical Sta- tics" 161, 274, 322, 385, 4C1

New Mountain Locomotive 563

Nickel in Norway 414

Obituary ; Geo. H. Mann ; John

W.Murphy 96

Oilfuel 328

Ore, Algerian 414

Paris academy 255

Paris geographical society 255

Paris water works 380

Passivity of iron 253

Pavements, s-treet 105

Pebble powder, recent improve- ments in the manufacture

of 549

Permanent way 336, 367

Peruvian Metals 570

Phosphureted Steel 562

Photographs, immense 208

Piers, iron 182

CONTENTS.

HI

Page.

Pollution of rivers 237

Port Said 188

Position of the neutral axes in a

bent beam 365

Pottery tree of Para 335

Powder, manufacture of Pebble. 452

Pressure, loss of in steam pipes. 155 Propeller raising and lowering

the screw of 93

Proportions of the heads of eye- bars 8

Puddling 362

Puddling, improvements in 2S2

Pumps, helical 88

Pumping engines A 471

Queen Ann style of architecture 59

Railways and rail trade of the

future 522

Rail trade of the future 522

Railways, block system for 332

Railways in Russia 307

Railways in the Celestial Em- pire 192

Railways, Narrow Gauge of Eu- rope 61

Railways, Rails used in the con- struction of 149

Rails, iron and steel 149

Rails, manufacture of steel 264

Rails, method of re-rolling 1S5

Rails punched in place by steam 474

Rails, steel 53, 432

Rails, steel, use of 272

Railroad, wooden 32

Railroads in Asia Minor 92

Railway axles 321

Railway carriages, suspended... 91

Railway companies in France.. 53

Railway construction, European 205

Railway engineers fur India 188

Railway, Moscow, Brest 451

Railway project in Belgium 302

Railway projects in the East 1S7

Railway runs 147

Railway, Siberian 474

Railway signals 444

Railway sleepers, preservation

of 283

Railway, underground, at Con- stantinople 474

Railwavs, American car wheels

for English 378

Railwavs of France 563

Rivers, Pollution of 23T

Page.

Rock- Boring Drill, Diamond 44

Rolling Stock, Improvements in 474

River pollution 534

Road making and building, rock, asphalt and concrete, in

applications to 526

Rock, asphalt and concrete in their applications to road

making 526

Russian iron clads 492

Russian Metallurgy 562

Safety Valves

Sanitary Engineering

Scientific Surveys

Screw of a Propeller, Raising & Lowering of

Sewers, Form and construction of

Sewers of Paris

, Signals, Railway

! Silicon in Pig Iron

>. Sinking of the Andes

Ships, Preservation of Iron

Skew Arches 97,193,

Slag, Use of blast furnace

Smelting of Iron in blast furn- aces

Street pavement question

: Streets

; Strength of bronze

, Strength of oak and Oregon pine

1 St. Gothard tunnel

j Society, Manchester

j Society, Metrological

; Society of Engineers, American

i Society of Engineers 89,

j Steam Pipes, loss of pressure in

| Steam Power of the world

j Steam, rails punched in place by ■ Steamer, the Bessemer Channel.

• Steel and Iron manufacture

I Steel association

'■ Steel, Bessemer and Siemens- Martin

I Steel, direct from Ore

; Steel, fluxes for

Steel, Heatou's system of mak- ing 90,

Steel, manufacture of.... 186, 300,

Steel production of France

Steel rails 53.

Steel rails, manufacture of

Steel rails, use of

Steel rails, as a substitute for those of Iron

109 356

44S

93

158 92 444 180 223 93 2^ 401

461 105 Sv)-2 259 359 9r; 90 10 282 376 155 8S4 474 296 283 282

473

91

186

409 432

204 272

149

Page.

Steel, tempering of 282

Steel wire 288

Steel bronze 514

Steel, manufacture of 545

Surveying, topographical 419

Surveying, topographical 489

Suez cannal tonnage 253

Survey, town of King's county . . 410

Surveys, scientific 448

Technical education 260

Technology of Iron 439

Telegraph cables 172

Temperatures underground 288

Tinning Iron Wire 570

Topographical surveying 489

Topographical surveying 419

Torpedoes aggressive 1

Town survey of King's county. . 410

Tramways in Vienna 409

Transit campaign, English and

American 370

Trial trips 35

Tubular floating docks 28

Tunnel at Constantinople 93

Tunnel, channel 284

Tunnel, channel, ventilation of. 417

Tunnel, Mont Blanc 285

Tunnel, St. Gothard 93

Underground railway at Con- stantinople 474

Valves, safety 109

Valves, experiments on safety.. 308 Ventilation, general principles of 17 Ventilation of the channel tun- nel 417

Vessels of war 31

Vienna exhibition, motors of . . . 343

"Wages, future of 3

Warner process 33

War vessels 31

Water supply, constant and in- termittent 38

Water supply of London 476

Water supply of Paris 92

Water works 380

Wire, iron, effect of acid on 303

Wire, iron or steel 288

Wood, black stain for . . 3S4

Wood, incombustible 366

Wool waste 201

World, round the 191

Wrought iron 362

YAN NOSTRAND'S

ECLECTIC

ENGINEERING MAGAZINE.

NO. LXXIII.-JANUARY, 1875 -VOL. XII.

submerged body were charged with com- pressed air of a tension which experi-

AGGKRESSIVE TORPEDOES.

From " Army and Navy Journal."

It appears that the constructor of the sharp lines employed, and the consequent IVhitehead Torpedo has recently modi- sacrifice of necessary capacity, unless the Hed his system in order to attain a very high rate of speed — the only possible expe- dient by which the disadvantage of not possessing any directing power can be, to some extent, met. Obviously the devia- tion from the intended course resulting from currents and other disturbing causes, after pushing out the torpedo, will be diminished in the inverse ratio of the speed of the submerged body. And, of course, the chance to strike an antagonist in motion will be greater in proportion to the increased speed of the torpedo. But, unfortunately, great speed cannot be pro- duced without resorting to such a form that the efficiency of the weapon will be seriously impaired, if not destroyed. Bearing in mind that the power neces- sary for propulsion increases as the cube of the velocity, we need not be sur- prised to find that the length of the im- proved "fish" torpedo has been aug-

mented to nineteen feet, while the diam- eter has been reduced to fifteen inches. Nothing short of such disproportion of length and diameter admits of lines suf- ficiently sharp to enable a submerged body to be propelled at the extraordinary rate of speed which, agreeable to the re- ports of our officers on the Austrian coast, has recently been attained by the "Whitehead torpedo. Nor could such speed be produced, notwithstanding the Yol. XII.— No. 1—1

enced engineers regard as dangerous. Re- cent accidents in Europe prove that an expansive force of one thousand pounds to the square inch, now employed by Whitehead, is not safe even for experi- mental purposes. But let us assume that workmanship and materials have arrived at such a state of perfection that we may safely handle the "fish," whose skin, agreeabie to reports furnished to the Bu- reau of Ordnance, is only one-eighth of an inch thick, and whose interior is charged with air exerting a pressure of 1,000 pounds to the square inch. The im- portant question then presents itself: will the new instrument prove sufficiently de- structive to sink a modern iron-clad ship ? The report referred to "states that the ex- plosive charge of the Austrian torpedo consists of t-ixty-six pounds of gunpow- der, placed, of course, in the forward end of the body, where, owing to its pointed form, the charge will occupy a length of nearly four feet. Hence, as the force of explosive substances contained in elon- gated vessels acts at right angles to the longest axis, it will be evident that the force of the long, taper, conical charge of the improved Whitehead torpedo — sup- posing that it strikes fair — will be ex- erted in lines nearly parallel to the skin of

CAPTAIN ERICSSON'S AGGRESSIVE TORPEDO SCALE, ONE QUARTER OF AN INCH TO THE FOOT.

2

VAN NOSTRAND'S ENGINEERING MAGAZINE.

the vessel struck. Apart from this grave circumstance, the fact should be consid- ered that the charge is of conical form, and that therefore the distance of the cen- tre of gravity of one-half of its mass is sit- uated only one-sixth of its length from the "base. Consequently, at the moment of ignition, fully one-half of the explosive energy will be wasted by expansion into the empty body of the torpedo, while the other half, acting at right angles to the axis of the torpedo, will, as before stated, exert its force in lines nearly parallel to the ship's side, and thus become partially harmless. Again, the portion of the charge near the apex of the cone, though in contact with the body struck, is too small in volume to exert destructive force.

The foregoing considerations point to the fact that the expedient of making ag- gressive torpedoes, long, slender and -pointed, in order to attain high speed in spite of the limited amount of motive en- ergy which can be stored within their contracted bodies, is incompatible with destructive efficiency. No system which does not admit of carrying a very heavy explosive charge, of such a form that the centre of gravity of the same is nearly equidistant from its outward limits, will prove adequate to destroy iron- clads con- structed on the admirable cellular plan of the Inflexible. Unless, therefore, some new motive agent can be procured many times more powerful for the space it oc- cupies, than atmospheric air compressed, the tubular-cable system must be resorted to, since that enables us to propel a body of sufficient capacity to carry an ex- plosive charge of sufficient magnitude. .Nor should the all-important fact be lost sight of, that the tubular-cable system enables us to control and direct the course of the torpedo. Regarding the proper form and size of the vessel which con- tains the explosive charge, we need hard- ly observe that, hitherto, that subject has received too little attention.

The reader will find an illustration on the front page, prepared from a draw- ing which Captain Ericsson has furnished to enable us to discuss the question of form and magnitude of charge, without entering into an elaborate disquisition. The section of the ship represented

which the aggressive torpedo is supposed! to strike, will readily.be recognized as-- that of the British iron-clad Devastation, Fig. 1 shows the top view of a torpedo carrying a charge of 400 pounds of nitro- glycerine. Fig. 2 shows the top view of another torpedo of nearly similar form,, carrying a charge of 1,000 pounds of the same explosive substance as the former. The slight difference in size of the two torpedoes will probably surprise those who do not reflect on the fact that, while the areas are as the square of the lineal dimensions, the contents is as their cube. Having in former issues of the "Journal'* minutely described the Ericsson torpedo, we need only remind the reader that the rudder is placed under the bow of the submerged body, and that the horizontal rudders, or fins, for regulating the sub- mersion, are placed one on each side, nearly amidships. The propellers, tubu- lar cable, and wire mast, with the colored ball at the top, for indicating the position of the torpedo, require no further de- scription. The blunt form of the bow wilt no doubt be objected to by naval archi- tects on account of the attendant in- creased resistance. In answer to this objection it suffices to state, that the un- limited amount of motive energy supplied through the tubular cable, renders the resistance of the torpedo of no account. Referring to fig. 2, it will be found on applying the scale, that the centre of* gravity of a charge of 1,000 pounds is situated less than twenty inches from the skin of the iron-clad ship. Experts are aware that the explosion of such an enormous charge, in actual contact, es- pecially as the mean distance of its mass is only twenty inches from the point struck, possesses adequate force to de- stroy iron-clad ships of any form what- ever. It is hardly necessary to observe,, that the cellular system will be of no avail if the force of the explosion be sufficient to break the ship partially in two. Possibly the constructor of the Inflexible is prepared to show that a charge of 1,000 pounds of nitro-glyce- rine is not sufficient to produce such an effect. If so, he will do well to consider that the tubular-cable system admits of doubling or quadrupling the stated charge.

THE FUTURE OF WAGES AND OF ffiON.

3

THE FUTURE OF WAGES AND OF IRON.

Remarks of Hon. Abram S. Hewitt, at the Bell-Whitwell Dinner, December 10, 1874.

Mr. President and Gentlemen : En- tirely satisfied as you must be after this bountiful repast with all things here be- low, unless it be the price of iron, I am, nevertheless, quite sure that you will be ill content with me if I were to deter for one moment the words of welcome to our cherished guests, Mr. I. Lowxthian Bell and Mr. Thomas Whitwell, which spring unbidden from the heart of every mem- ber of this goodly company of their fellow ironmasters, assembled to do them honor and to assure them of our profound re- spect and hearty good will. I will not attempt to disguise from them, as they

dustry, can be attained by any man, that of President of the British Iron and Steel Institute, the most enlightened and pow- erful organization for the advancement of a purely industrial interest which any nation has yet devised. In the course of his labors he has instituted an exhaustive series of experiments upon the operations of the blast furnace and its chemical phe- nomena, the results of which he has em- bodied in an elaborate treatise, which is justly regarded as the most valuable con- tribution in our day made to the laws governing the smelting of iron, and leav- ing but little to be done in that direction

surely will not disguise from themselves, jby future investigators. While his sue-

that this assemblage is of no common character and implies no ordinary com- pliment. They are to-night the honored guests of the whole American iron trade, and we rejoice that this opportunity is afforded to us to testify the high estima- tion in which they are held, and through them to acknowledge the great debt of gratitude which we in common with all the world owe to the land which gave them birth, for its numerous and inesti- mable contributions to the development of the production of iron in modern times. We honor Mr. Bell because he has done so much to make the iron business honorable. The son of an ironmaster, he inherited a position in the trade which might have satisfied his ambition without any special effort for its improvement; but from his early youth he carefully prepared himself for the intelligent ad- ministration of a great business by scien- tific training at the best schools, and by patient investigation of the principles which underlie the intricate processes of manufacture. Fortunately, perhaps, for himself and the world, his career has been identified with the most marvellous growth of productive industry — that of the Cleveland iron region — of which his- tory affords us any knowledge ; and to this development he has largely contrib- uted by his intelligence, his scientific training, and his rare powers of patient investigation. By these labors he has fairly won for himself the highest position which, in our special department of in-

cessful acquisition of knowledge, and the practical skill wtih wrhich he has applied it to useful purposes, would entitle Mr. Bell to very great and deserved distinc- tion, to us his chief merit lies in the fact that he has not kept his acquisitions to himself, or even to his own country, but has made haste to share with all the world the useful results of his labor, thus taking himself out of the category of a mere man of business laboring for his personal ad- vancement, and enrolling himself among the benefactoi s of mankind. And to Amer- icans he has a special claim to interest, not merely that he has his home at " Wash- ington, in the county of Durham," whence came the family of the ''Father of his Country," but that he dispenses there a generous hospitality, which makes the patriotic pilgrim and the wandering iron- master feel that they have returned to the home of their ancestors. For such, deserts the welcome which we offer here.- to-night is indeed all too poor.

We honor Mr. Whitwell because be also demonstrates the truth, which the world has come at last to admit, that the high- est science is necessary to insure the greatest economy in manufacture. His careful training as a mechanical engineer undoubtedly gave him special advantages, for a successful career as an ironmaster. By his energy, enterprise, and willingness, to test fundamental principles in prac- tice, he has contributed in a marked de- gree to the cheapening of the cost of iron,, and has therefore entitled him to the

VAN NOSTRAND'S ENGINEERING MAGAZINE.

thanks of all who are interested in the progress of civilization throughout the world. He is, so far as we are concerned, fortunate in having identified his name with the word " stove," which in America is always associated with the pleasant memories of "home." But his true title to the respect of mankind rests upon the fact that he has taught the world how to econ- omize fuel, and is therefore a conservator of force. His benefaction is direct and positive, and the measure of it is the number of tons of coal which will annu- ally be saved to mankind by his inven- tion. We might even venture upon a computation of his contribution to the wealth of this continent; but I fear that the result would be a sudden conviction on our part of the inadequacy of such honors as we pay to him to-night to dis- charge the obligations under which he has placed the iron industry of two con- tinents.

To such men as Mr. Bell and Mr. Whit- well, distinguished leaders in the great army of modern industry, too much honor cannot be done; and yet, with all their personal claims to our respect and affec- tion, it will derogate nothing from the compliment we have tried to pay them, if I say that these claims alone, strong enough as they are to open to them the home and heart of every ironmaster, would not of themselves have been sufficient to pro- duce this collective and unique demon- stration in their honor. To us they are more than members of the same frater- nity: they are representative English- men, citizens of a country to which the iron trade may be said to owe, if not its •existence, nearly all the great inventions and improvements which have enabled iron to be produced in quantity and at a cost essential to the growth of society and progress of civilization. To Great Britain the world owes the application of mineral coal to the smelting of iron ores ; the invention of the puddling process and of grooved rollers ; the introduction of the hot blast; the steam hammer; the Bessemer process ; the Siemens regenera- tive furnace; the Whitwell stove; the steam engine, locomotive and stationary ; contributions which, taken away, would relegate the world to a condition of bar- barism which the imagination refuses to contemplate.

We cheerfully recognize the primacy

of England in the domain of industry; and we are justly proud that we belong to a race which in the pursuit of material ends has used them as the means of as- serting the right of man to free govern- ment and of establishing social order up- on the eternal principles of truth and jus- tice. We recognize that, as in the world of industry, so in the domain of politics, she has taken no step backward, and we have learned from her history, which be- longs equally to us, that every new in- vention introduced, and every just politi- cal principle established, improves the condition of the working classes, and adds to the fund available for their better re- muneration. While we look with won- der on the mechanical and industrial achievements of Great Britain during the last hundred years, we feel that our ad- miration is rather due to the steady pro- gress which has been made in bettering the condition of the working classes and to the increase of comfort which they now enjoy, as the result of a better applica- tion of the natural forces and wiser leg- islation based upon sound economical principles. The steady rise of wages measured by their purchasing power in Great Britain, during the last quarter of a century especially, is the most encour- aging feature in the history oY mankind — a very rainbow of promise to the patient sons of toil throughout the world, because by comparing the past with the present the beneficent influence of sound legisla- tion on the welfare of the working classes thus becomes a matter of absolute dem- onstration. The abolition of the Corn Laws I regard as the turning point in the welfare of the industrial classes through- out the world, because it was a practical recognition in its most enlightened nation that the supposed interest of special classes, even when they govern, must yield before the force of public opinion, to the just claims of the governed. The immediate result of this change in British policy was and continues to be a very decided increase in the substantial remu- neration paid for daily labor.

But an advance of wages where there is no previous training for their proper use is not necessarily a benefit ; and after years of experience public sentiment in Great Britain has arrived at the conclu- sion that the general education of the masses is essential for their steady pro-

THE FUTURE OF WAGES AND OF IRON.

gress towards a higher social plane. And it seems to me that the step which has been recently taken in England towards the compulsory education of the masses, in spite of the opposition of selfish inter- ests seeking to retain their hold upon mere muscular force, to the exclusion of mental development, will add enormous- ly to the productive value of the work- ingman, and enable him to secure a rate of compensation justly due to such in- creased value. There may be those who falsely look upon a rise of wages in Great Britain, as the result of this better train- ing, with apprehension, and who predict that the supremacy of British industry will in consequence of the improved con- dition of the working classes pass away ; but it is to the honor of William E. For- ster, whose presence here we hoped to have to-night, that with the true instincts of a statesman, such as he exhibited when he was the eloquent champion of the American Union in the time of its peril, he was able to discern in the history of British legislation in its effects upon British industry the fundamental law that labor is productive in proportion to its intelligence, and that no more certain means could be devised for perpetuating the supremacy of Great Britain over other nations than by securing for the masses of the people a better education and a higher culture.

For the same reason the establishment of the British Iron and Steel Institute marks a new era in the international his- tory of industry. While it is true, as Mr. Bell justly remarked in his presiden- tial address at Liege, " that art and science recognize no geographical or political boundary," it is equally true that prior to the formation of the Institute the "secrets of the trade," as they were called, were jealously guarded, and access to works where special processes were carried on was extremely difficult, and often impos- sible, as well to foreigners as to natives. For the first time in the history of indus- try, the accomplished leaders of a great trade associated themselves together, not merely for the purpose of instructing each other in their special departments, of comparing experience, and of gather- ing together the latest discoveries in science and art for mutual benefit, but, with a liberality never before evinced ex- cept by scientific bodies, and which can-

not be too highly commended, all the world was made free to partake of the ad- vantages of this organization, so char- acteristic of the catholic spirit which hap- pily is beginning to mark our age. The beneficial results of this wise policy are already apparent in the general introduc- tion throughout Great Britain of the best machinery and the most economical pro- cesses, whereby the cost of producing iron has been cheapened, alike benefiting the consumer and increasing the ability to pay better wages to the operatives en- gaged in its production.

Not inferior in importance to the gen- eral advance in the British iron trade re- sulting from the establishment of the Iron and Steel Institute is the introduction and successful establishment in England of the principle of arbitration for the settle- ment of disputes between the employer and the employed as to rates of wages. While it cannot yet be said that the dis- astrous consequences resulting from strikes have been altogether averted, every intelligent man now sees that their occurrence is rendered more difficult, and that the good understanding between masters and men, so indispensable to the successful conduct of business, must be greatly promoted by the discussions and evidence which the contending parties are bound to have before an impartial um- pire. Arbitration not only pours oil upon the troubled waters of industry, but in fact is oil to the machinery of trade, keep- ing it in motion without jarring and stop- page from unnecessary friction. When the working classes come clearly to un- derstand how the fund available for the payment of wages is lessened by strikes and lock-outs, they will regard them as the greatest evils of the age, and, in this and every country where they enjoy the right of suffrage, will insist that the prin- ciple of arbitration in trade disputes shall be incorporated into the legislation of all industrial countries, and thus relieve themselves and the community from the dreadful suffering and irreparable losses resulting from any protracted stoppage of the machinery of production.

Great Britain also has the merit of hav- ing originated International Exhibitions of Industry, which in the judgment of all intelligent men have done more for the rapid progress of civilization than any other human agency ; and for the work-

VAN NOSTRAND'S ENGINEERING MAGAZINE.

Ing classes especially have been of incal- culable benefit, not merely in the enlarge- ment of their ideas, and the development of their tastes, but in patiently gathering together the facts which affect their social condition ; the rates of wages paid in dif- ferent countries ; the elementary means of education adapted to their wants ; the dwellings in which they are, as compared with those in which they should be housed ; the varieties of food and the methods of its preparation ; all of which have exerted an influence throughout Europe, and especially in Great Britain, which no lover of his race can overlook, and no statesman can afford to disregard. We are now about to avail ourselves of this grand humanitarian idea in our own country, and we are glad to learn by the cable to-day that Great Britain will take part in our Exhibition in 1876, the result of which must be the increase of national good will and an exchange of ideas which cannot fail to advance the interests of labor on both sides of the Atlantic.

In this connection there is another phase of recent industrial development in England as well as in this country which should attract the notice of all thought- ful men, in its bearing upon the question of the economy of production, and the consequent augmentation of the wages fund. I refer to the steady growth in the size and completeness of the establish- ments devoted to the production of iron, and, from the magnitude of the capital necessarily employed, their consequent transfer from individual to corporate ownership. Without entering into the question of the comparative advantage of these respective kinds of proprietorship, I desire to direct special attention to the facility which these corporate bodies offer for interesting the workmen directly in the ownership and the profits of the busi- ness; which, if generally availed of, must result in the final extinction of strikes and labor disputes, and thereby largely increase the earnings of the working classes, measured not by the day, but by the lifetime, and improve their moral and social standing. Now, Great Britain, in her corporate manufacturing companies, such as Crossley's, and in her legislation, which makes legal provision for " part- nership of industry," has set us an exam- ple of wise foresight, which we have, I confess, been slower to follow than could

have been anticipated, but possibly to be accounted for by the fact that these fine adjustments of conflicting interests are more necessary and feasible in older and more densely populated countries than in a new world like ours, where, as yet, the forces of nature have been appropriat- ed only to a moderate extent. Never- theless the example is before us, and we recognize that to us Great Britain is a great free school of industry, in which have been wrought out for us without cost the wisest institutions, the most com- plete machinery, the best processes, and the most advanced organizations for the conduct of industry which the experience of a free and enlightened nation overflow- ing with capital and energy has been able to elaborate.

You, gentlemen, and our distinguished guests will, I am sure, pardon this enumer- ation of the phases of industrial and so- cial progress especially apparent in the British iron trade, in view of the supreme importance to us here of the question of wages, and, above all, of the ability of Great Britain to pay a steadily increasing rate of wages, an ability which she is thus surely augmenting by the discoveries of her men of science and the inventions of her mechanics, by her wis,e and progres- sive legislation, looking to the future edu- cation and moral elevation of her work- ing classes, to the settlement of all trade disputes, and to the reconstruction of her industry on the enduring basis of practi- cal harmony between labor and capital. Every step in this direction is a benefac- tion to the United States as well as to Great Britain, and drives another nail into the coffin of international restrictive legislation ; and no one will hail with more enthusiasm than this body of Ameri- can ironmasters and their distinguished guests the advent of the day when all barriers to free commercial intercourse between the nations can be safely re- moved, by the equalization of the wages of industry which the enlightened states- men and scientists of Great Britain have done, and are doing, so much to bring about.

And this beneficent result cannot come too soon for the interest of the world at large. Although the business of making iron is everywhere passing through a stage of great stagnation, yet its future growth can be predicted to almost the

THE FUTURE OF WAGES AND OF IRON.

same certainty as we have learned to cal- culate the orbits of the heavenly bodies. In 1856, when the annual production of the world was about 7,000,000 tons, after a careful investigation I ventured to pre- dict that the production of iron would reach fourteen millions of tons in 1875. This limit was passed last year, when the product reached fifteen millions of tons. I do not think that I risk my character as a prophet when I indulge the belief that by the close of the present century twenty-five millions of tons per annum will be required to supply the wants of man. There are gentlemen in this room who will live to see this prediction veri- fied, for it covers only the life of a single generation. Great Britain, in 1856, fur- nished one-half the annual supply, and she has been able to maintain this ratio till the present time. But even Mr. Bell and Mr. Whit well, with all their natural confidence in the resources of the mother country, will admit they will be tasked to the utmost to keep up with the in- creasing demand for iron, at its inevitable rate of progress, when the total aggre- gate shall go beyond twenty millions of tons. Between Great Britain and our- selves, therefore, all possibility of rivalry must in the very nature of things soon pass away, and we shall then behold the magnificent spectacle of the two greatest and freest nations in the world co-operat- ing together for the extinction of ignor- ance, pauperism, and crime, and the ele- vation of the working classes throughout ■the world to that condition of comfort and intelligence to which they have a just claim, and which no political system can deny without laying the foundation of its own ruin.

We have a common language; we in- herit from England our common law and a priceless literature; we have govern- ments based upon the same political rights of man, and the equality of all men before the law ; we have the same social customs and standards, and the same love of home and the sanctity of the fam- ily relations ; we have the same great end in view in the amelioration and enlightenment of the working classes ; and, as if to provide us with the means of the speedy accomplishment of the liopes of all good men, we have, in the main, the control of that great fund of wealth and power which has been

stored up in the coal fields, and which is the key to the progress of civilization and the improvement in the condition of mankind. We are in fact but one fam- ily, endowed with the same training, oc- cupied in the same pursuits and aspira- tions, and blessed with the same moral and material resources. We are working to a common end, and by the unchange- able laws of nature we can work to no other ; and hence it is impossible for any intelligent man not to see that the laws which govern production, distribution, wages, and profit must sooner or later operate with absolute equality and free- dom between the two nations — if not be- tween the continents; and hence whoever is engaged in the promotion of this desir- able result, whoever hastens its advent by a single day, is the benefactor of this country, and should be its welcome guest.

Hence, Mr. Bell and Mr. Whitwell, we justify to ourselves, aside from personal grounds, this exceptional demonstration in your honor. You stand here to-night as representatives of England, our moth- erland, fruitful now as of old in good works and good examples, ever progres- sive in the development and application, of the eternal principles of truth and jus- tice ; striving still, as in the days of King John and Charles the First, and James the Second, to elevate the masses of the people to a better condition — foremost in the march of industry and of civilization ; and by the ties of blood and race, and in the possession of the joint estate of the coal and iron of the world, partners in- separable with us in the future benefac- tions to mankind which nature has put it in our power to confer.

Although commanded to speak words of " welcome," Mr. Bell and Mr. Whitwell, I am but too well aware that they are in reality the language of " farewell." Hence I have refrained from referring to the special facts of our development in the manufacture of iron, which you have both, carefully studied ; and in regard to wmich you will doubtless express your judgment at the proper time. We might regret perhaps that your visit has found us in. such depression; perhaps it may be more justly said in the throes of a new birth ; but it has at least this advantage, that you see the old passing away and a new era of science and mechanical excellence -

VAN NOSTRAND'S ENGINEERING MAGAZINE.

fairly inaugurated. For the first time in our history, we have a capacity for pro- ducing iron in quantity adequate to our consumption in a normal stnte of affairs, and when the old are fully adjusted to the new conditions, under which alone iron can be profitably produced, you will, I am sure, agree with me in one assertion, that it is the "manifest destiny" of this country to be the seat of an iron growth on a larger scale than the world has yet witnessed.

Gentlemen, in behalf of the American

Iron and Steel Association, which ha& honored me with this privilege,, because probably more than any other of its members I have enjoyed the boundless hospitality of the British ironmasters, I bid you "welcome and farewell," only in the hope that we shall be honored at our Centennial, in 1876, with the promised presence of the British Iron and Steel Institute, of which you, Mr. Bell, are the distinguished President, and you,, Mr. Whitwell, are so eminent an asso- ciate.

PROPORTIONS OF THE HEADS OF EYE-BARS.

From " The Transactions of the American Society of Civil Engineers.'

Ik the discussion of a paper on the pro- portion of pins, read by Mr. Bender, be- fore the Society during the past year,* the importance of a properly proportioned eye-bar was referred to, as exercising a considerable influence on the size of the pin. Reference was had to the published account of experiments made in England, up to the year 1869, from which it ap- peared that in order to secure the full strength of a bar it is necessary to pro- portion the head according to the dimen- sions given in Fig. 1. The method ob-

FlG. 1.

served in the manufacture of these heads is not stated in the published account of the experiments, but it is presumed that the bar is first rolled to the full width of the head, and then drawn down between the heads in a reversible mill to the re-

* "Proportion of Pins used in Bridges," by Charles Bender, C E., read before the Society April 2, 1873, and ^afterwards published in an extended form.

quired width, leaving the heads to be? forged to the proper shape under a ham- mer. The results of the following experi- ments confirm the general accuracy of the English standard, and an examination of the change in form of the head under strain will be of interest in assigning rea- sons for the conclusions arrived at.

The tests were made at the works of the Watson Manufacturing Company of Paterson, "N". J., during the month of De- cember last, under the direction of Mr. O. Chanute, for the purpose of determin- ing the character of the iron used in links for the newiron bridges on the Erie Rail- way. The testing machine was a hy- draulic press of approved construction,, and the behavior of the iron was believed to be in the main satisfactory. The re- sults in this particular will not be re- ported in detail, further than relates to- the subject under consideration. The heads of all the bars tested were made at the works of the Phillipsburg Manufac- turing Company, by the process known as die forging. The end of the bar is slightly thickened and drawn down to a wedge shape; a pile of scrap is then, placed upon it, and the whole heated to a welding heat, after which it is drawn, out under a steam hammer, and forged into the proper contour of the head by means of a vertical die, half of which is cut out of the anvil and half out of the- hammer. Three bars having a section of 4 by finches and 6 feet long, were broken, in the body of the bar, under an average- strain of 54,400 pounds per square inch j

PROPORTIONS OF THE HEADS OF EYE-BARS.

all of the bars indicating the same condi- tion of fracture as the specimen submit- ted. In each of these the heads were proportioned as in Fig. 2. After rupture the heads were found to assume the form indicated by the dotted lines ; from which it would appear that the proper disposi- tion of material upon a line G H is of the first importance, as tending to transfer strain from the bar to the back of the pin without undue concentration at the edge of the pin hole. If the amount of mate- rial upon this line were sufficient to pre- vent change of form, the lines of strain from the bar will arrive at the section DDina direction parallel to the bar, and the area of this section would then not require to exceed that of the bar itself. In practice it is not possible to effect this result absolutely, as will be noticed in the movement in this particular head ;

Fig. 2.

hence it is proper to increase that section by a certain proportion of the bar section ; in this case it is 30 per cent., while by the English standard it is 25 per cent. In determining a proper depth behind the pin, it should be borne in mind that from the nature of the manufacture of a head the fibre of the iron cannot be disposed in the direction of the strain with the same uniformity on this line as elsewhere, hence the necessity of allowing a more liberal margin for safety.

At the same time and place two bars were tested, having heads proportioned as in Fig. 3. No. 1 burst at the crown, under a strain of 44,000 pounds per square inch, the fracture snowing burnt iron for a distance of f inch inwards from the point. The broken head was subse- quently removed, and a new one made from Passaic Rolling Mill iron, was

welded to the bar by Watson's hollow fire process. Upon application of the

strain the bar broke through the Passaic- iron with 51,600 pounds per square inch.. No. 2 burst at the side of the head, on two lines, under a strain of 50,000 pounds,, the fracture showing slightly burnt iron. It is to be regretted that the scantling of these last bars was not the same as in the previous cases, in order that the compar- ative effect of pin diameter might have been eliminated. If, however, a head be designed for a 4-inch bar upon the same basis as in Fig. 3, it will be found (see Fig. 4) that the section on a line G H.

Fig. 4.

is considerably less than in the standard before you, and the depth behind the pin is also deficient.

The question as to whether the dimen- sions assumed in Fi^. 2 are the correct

%

VAN NOSTRAND'S ENGINEERING MAGAZINE.

ones for heads manufactured by forging or welding can scarcely be determined from the limited number of experiments referred to ; but by comparing the results with those obtained upon the same sub- ject abroad, it may be assumed that they approach very nearly to an accurate standard. One fact seems to be clearly indicated, namely, that it is not by in- creasing the section D D that stability is to be obtained, but by thickening the head in front of the pin in order to se- cure a proper distribution of strain in D D. Whether this rule applies to heads formed by the upsetting process, remains to be proved. The present practice in some establishments is to make D D 50 per cent, greater than the bar ; probably to counterbalance the effect produced by distortion of fibre in the manufacture ; and because of the difficulty of forcing the metal far enough back to maintain a proper width in front of the pin.

Inasmuch as the diameter of pin must first be known before the head can be proportioned, a table of pin diameters is annexed, varying for widths between 2 and 7 inches in flat iron, and up to 4f inches for squares and rounds. This table has been calculated upon the supposition that for flats thinner than 3£ to 1, the pin diameter should be 75 per cent, of the width of the bar, as indicated by the English standard. But inasmuch as the experiments upon which this ratio was determined, were made with the pin sup- ported on each side of the eye,* it be- comes necessary to consider the effect of a thick bar upon a pin projecting as from the top chord casting of a bridge. For .all practical purposes we may assume the pin to be in the condition of a cylindrical beam fixed in position at its supports and loaded with a weight equal to the strain upon the bar, distributed uniformly over a length of pin equal to the thickness of the eye. The formulae expressing the diameter of pin which shall not be sub- jected to a greater strain upon its ex- treme fibres than 10,000 pounds per square inch, under the above circum- stances, are as follows :

For flat bars —

D = 1.721 t /

(Eq. 1.)

* The diameter of pin in the experimental bar was de- termined with reference to heavier bars in the structure lot which it was intended.

In which t = thickness, and t n = width. For square bars, n = 1. For round bars, in which the thickness of head is -J of an inch less than the diameter of bar, the ex- pression becomes

(Eq. 2.)

In which D = diameter of pin, and d = diameter of bar.

By solving Eq. 1 for values of no greater than 3 1-2, it will be found that the value of D obtained will be less than 75 per cent, of the width of the bar ; hence, for all widths above this limit, the ratio 75 must be taken as determining the pin diameter. For other widths the formulae as above have been used in calculating the table.

Me. Collingwood — Mr. Macdonald has pointed out two primary considerations in the economical use of iron — form and condition of the metal. Unless these are thoroughly cared for, the consequent re- sult will be an increase of weight in our structures. Admitting, however, that these are as required, it seems to me that a third element should be taken into ac- count (even in deciding upon the first) and that is, the methods pursued in form- ing eyes, bolts and the like — not, how- ever, referring to the state Nin which the process employed leaves the iron, chemi- cally considered (that is burnt or un- burnt;, but to its physical condition, its compactness and the uniformity of its fibre.

In preparing the lower anchor bars of the East River Bridge for insertion into the masonry, four bars were left in the acid a little too long, and the result was to show the fibre in the eyes very plain- ly. The bars were 3X7 inches, section, about 13 feet long from centre to centre of pin holes, which were 5 inches, and the eyes 15 inches in diameter. The eyes were formed by hydraulic pressure, being first upset on the end and then pressed on the flat into a die which gave the per- fect shape. The two sides, edges and section of the iron in the pin-hole of one of the eyes are shown in the figures. The result of this process, as will be at once seen, is to cause the fibres to fold back upon themselves, and leave on each face (almost directly in the position pointed out by Mr. Macdonald as needing great- est strength) lines more or less depressed, the average depth being 1-16 to 1-32 inch.

PROPORTIONS OF THE HEADS OF EYE-BARS.

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The lines on the opposite faces were never opposite, but were from, on one side f to 1-J- inches further from, the cen- tre than on the other; in the bar shown, this distance was f inch. In some of the eyes also there was an appearance of looseness about the pin-holes shown by an actual separation of the fibre for -J inch. The bars were tested to 20,000 pounds per square inch without set. It is nevertheless certain that the iron in the eye was not in condition to give its great est strength. Even if we decline to recognize the existence of fibre, we can- not deny that iron is stronger in the di- rection in which it is rolled than in any other, and that well-worked, compact iron is stronger than that which is slight- ly worked.

I have been asked to describe the pro- cess of preparing the bars for the anchor chains of the East River Bridge, before they were covered up in the masonry. The bars had been painted, and when de- livered had considerable rust upon them. A long shed was prepared with an over- head travelling truck (cheaply made), to which were attached two differential pul- ly blocks for lifting the bars. Under- neath, at a convenient height for the workmen, was a double line of rails on which the bars could be slid along for painting ; at one end of the shed were placed, side by side, five vats. In the first was a solution of potash to remove

grease and paint; in the second and fourth, water for rinsing ; in the thirdr dilute sulphuric acid, and in the last was lime-water; the potash and lime vats were heated by steam. The strength of the solution is not very material, as it only affects the time required to produce the desired result.

Four bars were usually in each vat at once. The intent was to remove the scale entirely by the acid, but we soon found that the bars were eaten too much before it came off. Resort was then had to hammering to detach it, the object be- ing to secure a clean metallic surface. After cleansing, the bars were left in the boiling lime-water until thoroughly heat- ed. They* were then rinsed quickly, and while hot, coated with raw linseed oil. After this had hardened thoroughly, raw linseed oil mixed with Spanish brown and the boiled oil with Spanish brown were applied. The pin-holes were then thor- oughly cleaned, made smooth and rubbed with raw oil.

After the bars were put in position in the masonry, they were subjected to a heavy upward strain to bring them to bearing; they were then adjusted and wedged; next, thin grout was poured around the eyes and pins and rich con- crete filled around the bars. Recent ex- aminations at Niagara show that with our American cements, this process affords an absolute protection against rust.

THE MECHANICAL PROPERTIES OF BRONZES.

BY M. TRESCA.

Translated from "Annales du Conservatoire."

DrjKrNG the siege of Paris we had fre- quent occasion to ascertain the difference of results in experiments on the properties of bronzes; afterwards it seemed to us that it would be useful to determine more leisurely the properties of this alloy, of which the normal composition is 100 parts of copper to 11 of tin.

In the year 1872, in order to investigate the properties of bronze prepared with phosphorus, M. Morin procured two bars of bronze of the same dimensions ; one cast by the old processes, the other by the phosphorus process.

The dimensions were such that the casting could be made under the best con-

ditions. But tin spots were numerous,, and a great number of bubbles appeared on some of the surfaces. We have made our experiments on the clearest portions of these bars, detached and planed so as to afford solids of exact geometric form.

In 1870 we found that the most com- pact and homogeneous bronzes offered the most resistance to tension.

We made out of the Bourges bronzes small test rods, similar to those used dur- ing the siege ; and we should be satisfied with the figures we obtained, even were they not confirmed by other results. MM. Laveissiere, who made in 1870 more

THE MECHANICAL PROPERTIES OF BRONZES.

13

than 100 cannon, and sent specimens to the Vienna Exposition, allowed us to cut samples, so that we might test their pow-

the same dimensions as those from Bourges, and were submitted to the same test. The following is the composition,

ers of resistance. The samples were of as determined by M. L'Hote :

COMPOSITION.	BRONZE, Ordinary, of Bourges.	BRONZE, Phosphorus, of Bourges.	BRONZE, Laveissi^re, Mean of 3 analyses.
Copper	89.87 9.45 0.31 0.37	90.60 8.82 0.27 0.31	89.47
Tin Zinc Lead	9.78 0.66 0.09
Total	100.00	100.00	100.00

M. Alfred Tresca had charge of the ex- periments under my supervision.

That there might be no uncertainty in the results, it was necessary to vary the methods as much as possible.

The large bars of V.025 xOm.050 by a length of one metre could be tested only by flexion. Two bars have been used in each experiment, so that the coefficient of elasticity, the load and the extension cor- responding to the limit of elasticity have been determined for the Bourges and the phosphorus bronze. Another experiment in flexion had already been made upon the entire bars, from which the above were taken, with dimensions of 0m.060 x0m.100 by 2m in length. The coefficient of elas- ticity differed but slightly from the pre- ceding. It is the only coefficient which can result from special experiments in which no alteration is in any way made in the material.

The experiments in traction were more varied. In each case two bars were broken with dimensions of 0m.0.25 x 0m.025 by lm in length.

The elongations were measured with the greatest care by means of cathetome- ters. In this way have been determined the coefficient of elasticity, the load and elongation corresponding to the limit of elasticity, and the load and elongation corresponding to rupture. All these are shown in the table of coefficients. But of the last we have not taken account in the means for a reason given further on.

Experiments have also been made upon cylinders 0.0 12 in diameter and 0.15 long. Two parallel scratches, distant 10 centim. from each other, were repeated with the same opening of the compass along with the increase of the loads, so that each sample showed a record of all the opera- tions upon it. The first marks are almost

coincident for small loads, but for large loads they are very distinct, and it is these that are of real value as tests.

We have expressed in definite amounts only loads and elongation of rupture.

As regards the breaking load per square metre, the experiments show that it is always larger for the small cylindric sample than for the large square one. We have taken the mean of these two values.

The elongation corresponding to rup- ture has been referred to the metre in length, and the actual elongations have been increased tenfold for all measures deduced from the primitive length of 0m.10. This has led to results requiring explanation; and we shall avail ourselves of this opportunity to show how illogical is this method of evaluating great elonga- tions. As soon as the limit of elasticity is passed, they result at once from pro- portional elongation,' distributed with more or less regularity all along the piece, and form a purely local elongation corre- sponding to the sections most extended. Increasing this tenfold gives a false notion of the phenomena.

It would be better that the result should be obtained from a test-piece having the same dimensions in diameter and length.

The breaking load per square metre and the corresponding elongation are mani- festly affected by the form and size of the transverse section.

As we were not able to take a mean of the elongations measured for a length of one metre and a length of 0ra.10, we shall refer only to the last, which alone are ca- pable of comparison with the proof co- efficients in use for materials employed in ship or railway construction.

The following tables were calculated from graphic constructions :

14

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THE MECHANICAL PROPERTIES OF BRONZES.

15

Further explanations are necessary in order to better characterize the different properties. The experiments in flexion were not continued long enough to de- termine the modifications of the surface of the metal. It was, however, observed that there was a slight enlargement of the fissures upon the samples B.

The large bars showed in different de- grees a diminution of transverse dimen- sions in the section of rupture, especially between the middle points of opposite sides, where there was a sensible con- cavity in the parts most deformed. It follows that the total strain is not uni- formly distributed in the section, and these inequalities evidently indicate others in the transverse direction. The distribution of these transversal strains is probably not the same for all forms of section, and therefore does not cause the same displacements.

The bars B were fissured transversely at many points, especially upon one of the edges of the prism, which presented an appearance of serration; the surfaces were warped ; while the bars P are less deformed. The bars L show a more distinct nippling, with very slight fissures at the angles ; the section of rupture is reduced to 0.95 of the primitive surface.

The fractures have very different aspects :

B, metallic lustre ; broken surface ; many grains of tin.

P, earthy look ; granulated surface ; great uniformity.

L, metallic lustre ; granulated surface ; strained zone, paler than the rest of the section.

In the case of the cylindric bars the

variety of effects was still more charac- teristic.

The ordinary Bourges bronze broke without great elongation; the fracture was marbled with yellow and white, and ther& were at intervals small transverse fissures.

The phosphorus bronze had the same external appearance. There was no rup- ture of the wall ; its transversal fracture had no metallic lustre. It was quite uni- form in its dull and earthy look ; but there was in one of the samples a small spherical cavity filled with another com- pound, the presence of which undoubted- ly facilitated the rupture.

The Laveissiere bronze had a more- metallic and homogeneous fracture. It was particularly distinguished by the condition of its cylindric wall, which was bossed and nippled all along in a curious way ; probably indicating great malle- ability. The circular section became at some points almost polygonal.

On one of the samples were several transverse rents, hardly perceptible, re- sembling somewhat those occurring in the bronze of Bourges.

We have collected in the following table all the mean results of experiments, giving the values of the resistances of elasticity and rupture, Te and Tr, in kil- ogrammetres, of the work at the limit. The values i16 and T16 of elongation and of work corresponding to the load of 16.745k x 10, sufficing to break the or- dinary Bourges bronze, are united. In the same table appear Tredgold's coefficients from Poncelet, and • the ratios of co- efficients. Upon the relative values of Te and Tr depend the most essential and characteristic differences :

	BRONZE of Bourges.	BRONZE phosphorus.	BRONZE Laveissiere.	Poncelet's Figures.	RATIOS.
	Bronze	Bronze	Bronze
		-			of Bourges	phosphorus	Laveissiere-
E....	7k,589X109	8.250	9.061	7.00	1.00	1.09	1.20
J*...,	8k,961X106	8.667	11.210	7.30	1.00	0.99	1.25
*	lm,182X10-3	1.222	1.125	1.0	1.00	1.04	0.96
Tc...	5km,290X103	5.595	6.306	3.80	1.00	1.06	1.19
K,...	16k,715X106	21.827	26.270		1.00	1.31	1.57
%r....	36m,5X10-3	47.00	177.00		1.00	1.29	4.85
*16...	3m,65X10-2	1.02	0.68		1.00	0.28	0.15
T16...	129km,2X103	51.10	7.20		1.00	0.39	0.06
Tr...	129km,2X103	254.40	962.40		1.00	1.97	7.45

16

VANNOSTRAND'S ENGINEERING MAGAZINE.

At the limit of elasticity the elonga- tions vary little for the different bronzes, and the corresponding work is affected only by the slightly greater value of the corresponding resistance Re. This work is estimated by taking the integral of the products of the loads by the elongations. J)uring the entire period of elasticity, while the elongations are proportional to the loads, these quantities of work are easily estimated. Beyond this the work must be found by a quadrature of the curve, corresponding to the experimental sresults.

When the metal is very homogeneous, the rods elongate under loads much greater than those corresponding to the limit of elasticity ; so that the work of rupture for the best bronzes is relatively large.

En resume : 1° The coefficients of elasticity E for the bronzes B, P, and L are proportional to 1.00, 1.09, 1.20. Hence the coefficient rises one-fifth in passing from the weaker to the stronger bronze.

2° The bronzes B and P have the same limit of elasticity. That of the metal L exceeds this value by about one-fourth.

3° The elongations corresponding to this limit are proportional to 1.00, 1.04, 0.96 ; i. e., the elongation corresponding to the limit of elasticity is almost the same.

4° The work necessary to bring them to this limit varies from 1.00 to 1.06 and 1.19 ; the same ratios as for elasticity. •From these points of view the phosphorus bronze is better than the ordinary ; the Laveissiere bronze is decidedly superior to the others.

5° This is still more obvious in regard to rupture, for the coefficients are :

B 1.00

P 1.31

L 1.57

%r

1.00 1.29

4.85

1.00 1.97

7.45

The superiority of L is due to its great homogeneity.

6° The two last values, i10 and T16, are in inverse order ; since for each charge of 16 kilogrammetres per square millimetre, which suffices to rupture ordinary bronze, the others are not even brought to their period of striction ; the deforma- tions being very slight.

In the publication of these results, it is not our object to advocate any mode of fabrication ; but we confine ourselves to a statement of the following conclu- sions :

Bronze in general is not sufficiently homogeneous to warrant any one mode of experimentation alone, in the deter- mination of its properties.

In experiments it is best to operate on bars of dimensions equal in length and diameter, and to estimate breaking elongations only by direct experiment, without reduction to the metre ; since the deformations cannot be assumed to follow any law of direct proportion.

Finally there are commercial bronzes more homogeneous, resistant, and elastic than those made by the government ; for they suffer less deformation under a load and obtain a quintuple elongation be- fore rupture ; and seven times as much work is required to break them. We infer that industries are perfected under the stimulus of personal responsibility and interest ; and it is a matter of con- gratulation that the Direction of Artillery have decided to study in the foundries the best processes of fabrication.

The first annual meeting of the Amer- ican Metrological Society was held De- cember 29, President F. A. P. Bar- nard, LL.D., in the chair. Resolutions were passed approving the plan to se- cure a general adoption of the metric measures and weights in different profes- sions, after July 4, 1876. Also that the Society recommend the putting up of a standard yard and metre in the various

State capitals, under the standard to be made by the Bureau of Weights and Measures of the United States. The fol- lowing officers were elected for the ensu- ing year : President, F. A. P. Barnard, LL.D. ; Vice-President, the Hon. John A. Kasson ; Recording Secretary, Prof. C. G. Rockwood ; Corresponding Secre- tary, S. D. Tillman, LL.D. j Treasurer, Prof. R. W. Raymond.

GASES IN COAL MINES.

IT

ON THE GASES MET WITH IN COAL MINES, AND THE GENERAL PRINCIPLES OP VENTILATION.

By J. J. ATKINSON.*

The following remarks were written in the hope that some or other of them might prove of service in conveying to the merely practical miner a general knowledge of the laws and principles of ventilation, as applied to mines, and of the nature and properties, chemical and physical, of our atmosphere, as well as of those of some of the gases most fre- quently encountered in coal mines. They were not intended to have been commu- nicated to this or any similar institution, or they would, in all probability, not on- ly have been put into somewhat different language, but would also have placed some of the matters to which they refer in a more purely scientific point of view. But, after all, such an alteration would, perhaps, have rendered them less useful than it is hoped they may prove to the particular class of persons for whom they were written, such as underviewers, over- men, deputy-overmen, and even work- men who may wish to fit themselves for assuming any of these offices ; and, at the request of my colleague, your pre- sent President, I venture to submit them to your notice.

A variety of gases is given off by the coal and other minerals met with in coal mines ; a further supply of gases arises from the breathing of men and animals, and from the burning of candles and lamps, as well as from the explosion of the powder used for blasting the coal and stone in the mines. The whole of these gases are capable of causing the death of men and animals breathing them in their pure and undiluted state, and some of them require to be mixed with many times their own volume of air before the mixture they form with it can be breathed, for any great length of time, with safety. Some of the gases given off in coal mines, when mixed with certain propor- tions of air, form violently explosive mix- tures. Such a mixture of air and gas, on being ignited by a naked candle or other

flame, suddenly explodes and becomes

♦An

Society, Mines.

read before by J. J. Atkinson,

the Manchester Geological Government Inspector of

one mass of living flame, scorching and burning everything that may happen ta be in contact with it. Such an explosion, in general, also creates a complete hurri- cane, or tornado, of immense force and violence, tearing and driving all before it — knocking down the masonry erected for the guidance of the ventilation, as- well as the props and timber erected to support the roof of the mine, which falls in great masses, causing bodily injury or death to those it may fall upon, and often enclosing and imprisoning those who, be- ing unhurt by its fall, are left stunned by the concussion, more or less scorched by the flames, and, without lights, shut up to breathe the deleterious atmosphere pro- duced by the explosion. The flames of such an explosion being extinguished, and its violence exhausted, there remains an atmosphere so hot, and so charged with noxious gases and steam, as to cause the death of all who are left alive to in- hale or breathe it. This resulting atmos- phere is generally termed after-damp*

The grand object of the ventilation of mines is to cause such a current of air constantly to circulate through them as* shall, by mixing with and diluting the gases, render them harmless, and, in that state, carry them off as quickly as they are produced in the mines. It is here proposed, in the first instance, to remark upon the chemical composition of the air we breathe ; then upon that of a few of the most important gases met within coal mines, and afterwards to notice some of the leading principles of ventilation, by taking advantage of which we get rid of the gases as fast as they are given off int mines.

ATMOSPHEKIC A.IR.

Vol. XII— No. 1—2

Air is, almost entirely, a mixture of two gases, oxygen and nitrogen ; carbonic; acid is also present in limited but vari- able proportions, forming on an average about 1 part to 2,500 parts of our atmos- phere. Besides oxygen, nitrogen, and a trace of carbonic acid gas in the atmos- phere, there is always more or less of wTatery vapor diffused through the gases

18

VAN NOSTRAND'S ENGINEERING MAGAZINE.

of which it is composed ; but this vapor is variable in amount, is not considered as forming a constituent part of the at- mosphere, and is therefore not embraced in statements as to the chemical compo- sition of air; yet its effects are of the highest importance, both in the general economy of nature, and also in consider- ations relative to the ventilation of mines. Dry air is chemically composed of

By Weight By Volume.

Nitrogen Gas 77 per cent 79 per cent.

Oxygen Gas 23 " 21 ««

100

A cubic foot of air at the temperature of melting ice (32°), and under pressure of 14.7 lbs. per square inch, or 2,116.8 lbs. per square foot, weighs 0.080728 lbs. ; so ^that under the same conditions 1,000 cubic feet weigh 80.728 lbs. avoirdupois.

NITROGEN GAS.

Nitrogen gas is rather lighter than air taken in equal volumes, at the same tem- perature, and under the same pressure. 'The specific gravity of air being taken as 1,000, that of nitrogeng as is only 971.37, so that the weight of 1,000 cubic feet of air being 80.728 lbs., that of 1,000 cubic feet of nitrogen is only 78.416 lbs. at the temperature (32°) of melting ice, and un- der the pressure of the atmosphere, taken at 14.7 lbs. per square inch, or 2,116.8 lbs. per square foot. A cubic foot of nitro- gen, under the same conditions of tem- perature and pressure, weighs 0.078- ^4167 lbs., and a cubic foot of air 0.080- 728 lbs., as before stated.

Nitrogen gas has neither color, taste, nor smell, and so far it is like air itself. It will not support life, but causes death when breathed. It will not support com- "bustion, but extinguishes lights. This gns has very little chemical affinity or at- traction for other bodies ; its chemical properties are rather those of indifference than of activity; its position amongst •gases, in general, being almost like that •of water amongst liquids, as it serves to ■Tender their properties less active. It di- lutes the oxygen of the atmosphere, which could not long be breathed with- out being diluted with nitrogen. Nitro- gen is, however, probably the best part -of manures for land; and it is a compo- nent part of nitrous oxide or laughing gas, of ammonia, and of nitric acid, or aqua-

fortis, as well as of many other com- pounds.

OXYGEN GAS.

Oxygen gas, as has been stated, forms about 21 parts by volume, or 23 parts by weight out of every 100 parts of air, be- ing rather more than one-fifth part. The specific gravity of air being taken as 1,000, that of oxygen gas is 1,105.63; 1,000 cubic feet of air at 32°, and under a pressure of 14.7 lbs. per square inch, weigh 80.728 lbs.; 1,000 cubic feet of oxy- gen gas, under the same conditions, weigh 89.255 lbs.; so that this gas is rather heavier than an equal volume of air. Oxygen gas has neither color, taste, nor smell. This gas, in a free and uncombined state, is essential to life ; we must breathe it in this state or die ; in its undiluted state, it is not fit to breathe be- yond a very short time. In our atmos- phere it is fitted to sustain life by dilu- tion or mixture with nitrogen gas. Che- mical compounds in the gaseous form may contain large proportions of oxygen and yet be unfit for respiration or breathing ; to be suited for this purpose, the oxygen must be free and uncombined, and at the same time diluted.

Oxygen is the most abundant substance in nature, and constitutes^ at least one- third of the solid mass of the earth — 23 per cent, of air and 89 per cent, of water. Oxygen has strong affinities, and com- bines with all known substances except fluorine. It forms, with other substan- ces, no less than 136 inorganic com- pounds, and it would be difficult to say how many organic ones. This gas is the great supporter of combustion. Substan- ces that burn in air burn much more vi- vidly in pure oxygen, showing that the oxygen in the air is the supporter of combustion. Iron wire will burn in oxy- gen, but not in air : and this is also the case with other metals in a finely divided state. When, by breathing, we inhale air into our lungs, a part of the oxygen it contains combines with carbon, and we exhale or breathe out, as the result, an equal quantity, by volume, of carbonic acid gas, and, consequently, liberate about 3" times as great a volume of free nitro- gen gas.

Having glanced at the chemical con- stitution of the atmosphere, let us next consider that of the principal gases met with in coal mining.

GASES IN COAL MINES.

19

CARBONIC ACID GAS.

When this gas is met with in coal amines it is often called sty the, choke- d.tmp, or black damp. It is composed of oxygen and carbon. We have already considered the nature of oxygen as a component part of the atmosphere, but we must not expect to find it show the same properties wlien chemically com- bined either with carbon or any other substance whatever. Carbon, the other part of choke-damp, forms the chief in- gredient in coal ; and coke contains a still larger proportion of this substance: but the diamond is pure carbon, in a crystal- line state. The chemical composition of carbonic acid gas is —

By Atoms. By Weight. By Volume.

Oxygen 2 ... 72.73 per cent 1

Carbon 1 ... 27.27 " 1*

100.00

1 condens'd.

Now, although this gas contains nearly 3 parts out of 4, by weight, of oxygen (the life-supporting element), yet, because it is combined with another substance (carbon), the result is, in this case, a poi- sonous gas. It is dangerous to life to breathe air containing 8 per cent., or one- twelfth of this gas. Lights are extin- guished in air containing 10 percent., or one-tenth of it. At 32°, under a pres- sure of 14.7 lbs. per square inch, 1,000 cubic feet of air weigh 80.728 lbs., and 1,000 cubic feet of carbonic acid gas weigh 123.353 lbs., so that it is rather more than 1\ times as heavy as an equal vol- ume of air. The specific gravity of air being 1,000, that of carbonic acid gas is 1,528.01. Before being mixed with air it rests next to the "thill,1' or floor, of mines, owing to its great heaviness or density when compared with air. This gas, besides being given off naturally in many mines, is always found to result from the breathing of men and animals, the burning of candles and lamps, and, mixed with other gases, from the explo- sion of the powder used in blasting. Near the mouth of an adit or drift at Butterknowle Colliery, in the County of Durham, the writer has seen several small Thirds lying dead from the effects of this gas. They had come to feed upon crumbs where the workmen ate their

* Bunsen assumes the hypothetical volume of carbon at one-half of that assumed here ; but as he gives its density at double the value here given to it, the results are not al- tered.

meals, close to the mouth of this, an aban- doned drift, and the gas coming out of the drift at the level of the ground had overcome them. At the same colliery, in several places where the coal has been worked away, the ground has been rent up to the surjace, and it is said that birds flying across these rents or pitfalls, in some instances, are so quickly affected by the escaping gas as to drop into the holes and die there. Without disputing the fact of dead birds being found in the holes, the reason assigned as the cause of their coming there appears to be rather doubtful. The effect of the gas is not, perhaps, so instantaneous as to account for it. Unfortunately, birds are not the only sufferers from this gas, for many human beings have met their deaths through breathing it; and in many other cases injurious effects are produced on the health of workmen through the mixture of this gas, in small proportions, with the air of mines.

Limestone consists of carbonic acid and lime, and chalk is of a similar composi- tion ; these ingredients, however, being generally mixed with oxide of iron, mag- nesia, and other substances in less but variable proportions.

PROTO-CARBURETTED HYDROGEN GAS,

LIGHT CARBURETTED HYDROGEN GAS, OR, AS IT IS SOME- TIMES CALLED, MARSH GAS.

This gas is the fire-damp of mines. It contains one atom of carbon combined with two atoms of hydrogen, or some multiple of these. Taking the atomic volumes of carbon and hydrogen to be the same, it contains one volume of car- bon combined with two volumes of hydro- gen— in all three volumes — but the three volumes are condensed into one volume of fire-damp. The weight of air at the temperature of melting ice (32°), and 14.7 lbs. per square inch pressure, is, for 1,000 cubic feet, 80.728 lbs.; that of 1,000 cubic feet of gas, under the same condi- tions, is 45.368 lbs., so that the specific gravity of this gas is 562*, that of air be- ing 1,000, it being rather more than half as heavy as an equal volume of air under the same conditions. Owing to the fire- damp of mines being lighter than air, it lodges next the top or roof in mines, until, by diffusion, it gets quite mixed with the air. This gas would soon cause

* Professor Bunsen gives the specific gravity of marsh gas at .55314, that of air being 1.

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

death if breathed in a pure and undi- luted state ; but, when mixed with twice its own Yolume of air, it may be breathed for some time without serious effects. It quickly extinguishes lamps or candles when unmixed with air. Fire-damp, or light carburetted hydrogen, contains nearly 25 per cent., by weight, of hydro- gen. Hydrogen is the lightest known gas, being only one-fourteenth part of the weight of air. The hydrogen in fire- damp is, however, condensed into a smaller volume than it occupies in a free state. Light carburetted hydrogen gas is chemically composed of —

By Atoms. Hydrogen ... 2 Carbon ... 1

1

By Weight.

. . 24.6 per cent.

... 75.4

100

By Volume. ... 2 ... 1

1 condens'd.

In the fire-damp of mines, however, we find a small proportion of other gases mixed with it. "When 1 part of fire-damp is mixed with 30 parts of air, by volume, its presence can be detected by the ap- pearance of the flame of a candle ; and as the quantity of fire-damp is gradually increased from 1 up to 2 parts in 30 of the air, the appearance of the flame is more and more affected by it; but even in the lat- ter proportion the mixture will not ex- plode. The flame t of the candle is sur- mounted by a pale blue halo, called in mining language a " top," or " cap," which partakes more or less of a brown color, ac- cording to the quantity of stythe, or car- bonic acid gas, that may be present along with the fire-damp. The examination of the flame, for the purpose of forming a judgment as to the quantity of fire-damp mixed with the air, in mines, is, in mining

dialect, called " trying the candle ,"or "try- ing the lamp." When the fire-damp forms as much as 1 part out of 13 of the airy the mixture becomes explosive, so that, if ignited by an exposed flame, the whole of the mixture is converted into a mass of flame ; in this state of the mixture, however, the force of the explosion is comparatively feeble. When there is only 9 to 10 times as much air as fire-damp, the explosive force is greatest. If the proportion of gas be greater than 1 part out of 9 to 10 of air, by volume, the force of explosion gradually becomes less and less, until there is only five times* as- much air as gas, when the mixture will no longer explode, but, on the contrary, will extinguish the flames of candles or lamps that may be brought into it.

The presence of carbonic acid gas, or of free nitrogen gas, in mixtures of fire- damp and air, is found to lessen their explosive force ; so that if we add to the most explosive mixture one-seventh part of its volume of carbonic acid gas, it will not explode at all. Air containing one- fourth part of fire-damp, by volume, may be breathed for some time without very serious effects being produced on the animal frame. Common coal gas, as used for lighting, contains a large pro- portion of light carburetted hydrogen gas — the fire-damp of mines. Besides this, however, it contains a considerable proportion of pure hydrogen, some car- bonic oxide, and some olefiant gas.

When a mixture of air and fire-damp is exploded, the chemical changes that take place, and the nature of the result- ing mixture, or after- damp, are as fol- lows :

Air

Fire-damp.

MIXTURE BEFORE EXPLOSION.

By Atoms.

Relative No. of Volume Atoms, per Atom.

j Oxygen 4 x 1

{ Nitrogen 7.4 x 2

j Carbon 1x2

{ Hydrogen 2 x 2

	By	Measure.
Uncombined Volume.		Combined Volume.	Volume per cent.
== 4 = 14.8	\	18.8	90.385
= 2 == 4	I	2	9.615

24.!

20.8 100.000

* "Even when mixed with three or nearly four times its bulk of air it burnt quietly in the atmosphere, and ex- tinguished a taper.'' •« When mixed with between 5 and 6 times its volume of air it exploded feebly." " It ex- ploded with most energy when mixed with 7 or 8 times its volume of air, and mixtures of fire-damp and air re-

tained their explosive power when the proportions were 1 of gas to 14 of air. 1 of carbonic acid added to 7, or 1 of nitrogen added to 6 parts of explosive mixture rendered them inexplosive."— i*Yom the Collected Works of Sir H. Davy, page 10, Vol. VI., 1840.

GASES IN COAL MINES.

21

MIXTURE AFTER EXPLOSION.

By Atoms.

By Measure.

Relative

No. of Volume Uncombined Combined Volume

Atoms, per Atom. Volume.

Volume, per cent.

Tree Nitrogen

Carbonic Acid j Carbon

Gas "j Oxygen

j Hydrogen

••'* (Oxygen

Steam

7.4

1

2

14.

2 2 4 2

24.5

14.8 2

20.8

71.2 9.6

19.2 100.0

Before explosion, there may happen to be present either an excess of air or of fire-damp, beyond what is necessary to cause the explosion ; and if so, they will remain mixed with the after-damp, in an unchanged state, after the explosion has taken place. There never can, however, be such an excess of air present as to render the after-damp fit to breathe, or the explosion could not take place ; the limits are such that this is impossible. The above proportions of 1 of fire-damp to 9.4 of air form the most explosive mixture, all other proportions forming less explosive mixtures.

From the second table, we perceive that the after-damp contains between seven and eight times as much free nitro- gen as carbonic acid gas, or choke-damp. It was, at one time, a popular mistake to suppose that the injurious part of the after-damp consisted only of carbonic acid gas, or choke-damp — not amongst scientific chemists, but amongst respect- able mining authorities — and that, not very long ago. After-damp, it may be seen, by the second table, contains about 71 parts of free nitrogen, 9£ parts of carbonic acid gas, and at the moment of explosion, 19 parts of steam ; so that it may be said, at this stage, that after- damp contains, in round numbers, seven parts of nitrogen, one part of carbonic acid gas, and two parts of steam, out of a total of 10 parts. Directly after the explosion, a large part of the steam con- denses and leaves, as a residuum, about 7-| parts of nitrogen and one part of car- bonic acid gas, out of eight and one-half parts ; the whole unfit to breathe, and incapable of supporting either life or combustion. A small excess of air, or of fire-damp, might be left mixed with the after-damp of an explosion, beyond what is noticed in the tables as being chemi- cally changed ; but in no case could the air of the after- damp contain less than

twice its own volume of deleterious gases, or the explosion could not have taken place ; such a mixture, if breathed, would soon cause death. Since explo- sions cannot always be prevented, how important it is, then, to be prepared to mix and dilute the after-damp with fresh air, in as speedy a manner as possible,

. after their occurrence. If there is more fire-damp present than is chemically

I changed by an explosion, the force of the explosion itself is lessened, but the after-

I damp resulting is more deadly than if an

I excess of air had been present at the

| time of explosion. ■

I CAKBONIC OXIDE.

This gas is sometimes called white- damp, when met with in mines. Assum- ing, as before, that the atomic volume of 1 carbon is twice as great as that of oxygen, its composition is as follows :

By Atoms.

I Oxygen 1 .

I Carbon 1 .

By Weight. .. 56.69 .. .. 43.31 ..

100

By Volume. .. l

1 condensed.

Its specific gravity is 975.195, that of air being assumed at 1,000 ; so that 1,000 cubic feet of air at 32°, and under a pressure of 14.7 lbs. per square inch, weighing 80.728 lbs., an equal volume of this gas under the same conditions will weigh 79.426 lbs., and one cubic foot un- der the same conditions will, therefore, have a weight of .079426 lbs.

Carbonic oxide has a much more dele- terious effect on the animal economy than carbonic acid ; air which contains only one per cent, of carbonic oxide al- most immediately causes the death of warm-blooded animals, as has been shown by the decisive experiments of M. Felix Leblanc. Carbonic oxide is itself an inflammable gas, but does not support the combustion of other bodies. It has no taste, but has a peculiar odor. Small animals immersed in it die instant-

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VAN NOSTRAND'S ENGINEERING MAGAZINE,

ly. When inhaled, it produces giddiness and fainting fits, even when mixed with a fourth of its bulk of air. It is easily kindled, and burns with a blue flame, be- ing transformed into carbonic acid by the process. The carbonic acid formed by combustion at the bottom of a coal, coke, or charcoal fire is sometimes con- verted into carbonic oxide, by being de- prived of a part of its oxygen, as it passes upwards through the red-hot em- bers ; and, on coming into contact with the air, at the top of the fire, burns there, with a blue flame, and is again converted into carbonic acid gas. This gas is, per- haps, never found in coal mines except as the result of the explosion of gunpowder, or the combustion of coal or wood. Car- bonic oxide is obtainable in a state of purity by heating yellow ferro-cyanide of potassium with eight or ten times its weight of oil of vitriol. Bunsen obtained it by slightly heating a mixture of formic and sulphuric acids ; and to ensure the perfect purity of the gas, he passed it through a concentrated solution of caus- tic potash. Such a proportion of this gas might be mixed with air as to form a mixture in which candles or lamps would burn, while life would become ex tinct ; and it is probable that many deaths in mines have resulted from this gas, in situations where the lights have continued to burn.

It appears to be very probable that the deaths of the men and boys in the late accident at Hartley Colliery arose in a great measure from this gas given off by the furnace, after the stoppage of the air-current by the closing of the shaft ; inasmuch as the lights used by the work- men engaged in clearing the shaft ap- peared to be rather increased in brilliancy than otherwise at the time when the worst effects were felt from the escaping gas ; and the mine gave off no fire-damp and very little choke-damp.

At page 120, in the minutes of evi- dence taken before a Select Committee of the House of Commons, on accidents in mines, in 1835, the late George Stephen- son, in reply to question 1853, gives an account of an accident at Newbottle Colliery, by which several persons lost their lives by a gas in which the lights burnt well, and which the witness sup- posed to have been sulphuretted hydro- gen gas; but it appears to be more prob-

able that it was a mixture of carbonie oxide, sulphurous acid, and a small- quantity of carbonic acid gases, gener- ated by the explosion of gunpowder in the drift, where it was found to prevail ; because sulphuretted hydrogen gas has a particularly offensive smell, of which no mention is made in the account of the accident.

The writer is acquainted with several instances where gases have caused deaths, and with others where they have caused severe indisposition, in places where can- dles continued to burn brightly ; in some of these cases, the gases were apparently produced by the explosion of gunpowder, and in others, by the combustion of coals; and hence it appears to be probable that carbonic oxide was a prominent ingredi- ent in them. In an experiment by M. Leblanc, a large-sized dog was asphyxiat- ed in an atmosphere which contained 4 per cent, of carbonic acid, and only -§■ per cent, of carbonic oxide.

HYDKO-SULPHURIC ACID, OR SULPHURET- TED HYDROGEN.

This gas is sometimes met with in coal mines. It is colorless, but distinguishable by its unpleasant smell, which resembles that of rotten eggs. It produces fainting fits and asphyxia, if inhaled, even when present only in very small proportions with atmospheric air. When inhaled, in its pure state, it acts as a powerful nar- cotic poison. It does not support combus- tion, but is itself inflammable, and burns when exposed to a supply of air and ignit- ed ; and, when mixed with oxygen gas, the mixture is explosive. It reddens tincture of litmus, but the reddening dis- appears on exposure to the air.

The composition of sulphuretted hydro- gen is as follows :

By Weight.

By Volume., ....l-6th .. 1

By Atoms.

Sulphur 1 94.15

Hydrogen 1 5.85

1 100 1

According to Bunsen, the specific gravity of this gas is 1,174.88; that of air being assumed at 1,000, under the same conditions as to temperature and pressure. Sulphur heated strongly and repeatedly sublimed in fire-damp freed from oxygen by phosphorus, produced a considerable enlargement of its volume, sulphuretted hydrogen was formed, and charcoal pre-

GASES IN COAL MINES.

23

cipitated ; the volume of sulphuretted hydrogen produced (ascertained by ab- sorbing it by solution of potassa) was ex- actly double that of the fire-damp de- composed.

Sulphuretted hydrogen gas may be in- flamed by charcoal or iron, even at a low red heat. In air it burns with a blue flame, forming water and sulphurous acid, and depositing sulphur. According to some authorities, 1-1 500th part of this gas in air is instantly fatal to small birds, l-1000th killed a middle-sized dog, and a horse died in an atmosphere that con- tained l-250th part of its volume. The presence of sulphuretted hydrogen gas in the atmosphere, even in small propor- tions, can be detected by its action upon moist carbonate of lead, spread upon white paper, which it blackens. M. Parent Duchatelet observed that work- men breathed with impunity in an atmos- phere containing 1 per cent, of sulphur- etted hydrogen, and he states that he himself respired air containing as much as 3 per cent, of the gas, without experi- encing any serious, results. This gas is formed whenever sulphur in a very com- minuted form is brought into contact with hydrogen in the act of being given off, and is probably formed, to some ex- tent, where pyrites is undergoing decom- position in mines. When this gas is pres- ent with the air, in mines, candles will burn in the mixture, so that, if it is not detected by its odor, it may prove fatal to life before its presence is detected.

It appears to be probable that this gas is frequently formed in old unventilated workings partly filled with water. There are two instances mentioned by Mr. Nicholas Wood, in his evidence before the Committee of the House of Commons on accidents in mines, in 1853 — one at Hartley Colliery, which proved fatal to one person, and another at Tyne Main Colliery, where ill-effects were felt, not- withstanding that th# lights burnt well ; both of which, in all likelihood, were due to the generation of this gas from the ac- tion of the water upon pyrites in old workings.

A man breathes into his lungs about one-fifth of a cubic foot of air per minute, and converts about seven per cent, (by volume) of this into carbonic acid gas, which, with about three and three-quarter times as much free nitrogen, he exhales,

along with about 66f per cent, of the air he breathes, in an unchanged state. The largest lamp used in mining converts less oxygen into carbonic acid gas than a workman. Both give off water vapor as well as carbonic acid gas. When coal is on fire, it gives off, in burning, carbon- ic acid, carbonic oxide, and sulphurous acid gases. The explosion of gunpowder gives rise to carbonic acid, nitrogen, car- bonic oxide, and steam, besides carburet- ted and sulphuretted hydrogen in small proportions. In the ordinary course of mining, these causes give rise to so small a quantity of gas, in proportion to the air, that they hardly belong to the sub- ject in hand, unless in reference to the state of a confined and unventilated part of a mine, where a shot has been fired, or in the more rare case, of coal being on fire in a mine.

Sir Humphrey Davy discovered that the flame of ignited gas would not pass through fine wire gauze, containing 28 holes for each inch in length, orT84rholes per square inch, unless the gas is moved with great velocity against the gauze, or the gauze against the gas ; and by en- closing the flame of an oil lamp in a cage? made of this gauze, we are able to carry a light into an explosive mixture of air and gas without setting the gas on fire on the outside of the gauze ; by this means an explosion is avoided. If we find our- selves with a safety-lamp in an explosive atmosphere, we should only try to put out the flame by carefully drawing down the wick, and by no means try to blow it out, or we might blow the flame through, the gauze, and cause an explosion. An explosion might result from drawing the flame of the lamp through the gauze by- means of a tobacco pipe ; yet workmen are not unfrequently detected in this very- daring and dangerous practice in mines. Outside-feeding, or oil-tubes, used to be attached to safety-lamps, but these are> dangerous, as the flame might pass down the wick tube, and up the oil tube, and so fire the gas on the outside of the lamp,, if the oil-plug was out or fitted badly,, and the wick was small compared wTitli the tube ; but feeding tubes are not used now, at least in many districts. There are several sorts of safety-lamps now more or less used, which give more light than the Davy-lamp ; glass being used in lieu of gauze opposite the flame. Glass

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VAN NOSTRAND'S ENGINEERING MAGAZINE.

is brittle, and liable to crack from un- equal expansion, and many persons do not think glass lamps so safe as the Davy, in consequence. The late George Stephen- son contrived a safety-lamp, having both glass and gauze around the flame, known as the Geordy, or Stephenson lamp. The Davy lamp is perhaps the best known lamp for detecting the presence of a small mixture of fire-damp in the air of a mine. Now since fire-damp, choke-damp, and other gases are met with, in more or less ■abundance, in all coal-mines, it becomes an important question as to how the bad •and often fatal effects they are likely to produce, if not properly dealt with, may best be avoided. To this end it has sometimes been proposed to get them to combine chemically with some sub- stance to be presented to them as they are given off; and only a short time ago a Mr. Wall had a proposition of this kind before the public. So far, however, the best mode of dealing with them appears to be to dilute them with very large •quantities of fresh air, and to sweep them out of the mine by an energetic ventila- tion, as fast as they are given off or gen- erated. After all, however, the natural laws and principles, operating in the pro- duction of ventilation in mines, have been less generally studied in England than on the Continent ; and from this cause many mistakes have been made in the prac- tice of ventilation in this country. New arrangements for the ventilation of mines have sometimes been made at great cost, and have not been found to answer when completed. In a few cases, lives have been lost from this cause ; in others, an inferior arrangement and ventilation have been produced, where, by the application of these natural principles, a superior one might have been obtained at the same or even at a smaller cost. Many, if not all the members of this Society, are familiar with the details of the general practice of ventilation as pursued in this country. Instead, therefore, of considering this part •of the subject, it is here proposed rather to direct attention to the natural laws and principles affecting the ventilation of mines.

NATURAL LAWS AND PRINCIPLES AFFECT- ING THE VENTILATION OF MINES.

As an introduction to the general laws .and principles affecting the ventilation of

mines, let us notice some of the general physical properties of air and gases. The world on the surface of which we live is a large globe, about 8,000 miles in diam- eter, and 25,000 miles in circumference. This great globe is surrounded by, and en- closed in, an atmosphere of air many miles in depth ; so that the surface of the earth, where we live, is the bottom of a deep sea, or ocean of air. Air is composed of the two gases, oxygen and nitrogen, in the proportions that have been named. Air and all gases have the following physical properties : They are impene- trable. If any space be filled with air, no other material body can occupy the same space without first displacing the air, because no two material bodies can be in the same place at the same time. Two gases, or a gas and a vapor, may fill the same space (in a certain sense), by being mixed with each other, in the same manner that a sponge -will hold water, but each gas or vapor must leave spaces vacant for the other to occupy or fill. Air and gases are possessed of the pro- perty called inertia. » With respect to motion and rest, air, gases, and indeed all kinds of matter, are said to be inert, so that they will remain either at rest or in the same state of motion, until acted upon by some force or resistance. This pro- perty merely implies what may be termed a negative quality, of such a character as to have the effect of causing matter not to change its state, whether of motion or of rest, without some force or resistance being applied to it to cause it to do so. Owing to the property of inertia, a body will remain either at rest or in the same state of motion, both as to speed and di- rection, in spite of any forces or pressures that may be acting upon it, provided they are equal and opposite forces, so as to counterbalance each other. This is the state of the atmosphere in a calm : there is always a pressure in every direction, up, down, sidewaj%, diagonally, and in fact in every direction, in the air of the atmosphere. This pressure arises from the mere weight of the superincumbent air, and amounts, generally, to nearly one ton on each square foot, or 14 lbs. and up- wards per square inch. If the pressure is lessened on one side, the ordinary pressure upon the opposite side drives the air towards the side where the pressure is reduced, and gives rise to a wind. If

GASES IN COAL MINES.

25

the pressure is increased on any side, the air is driven away to the opposite side, against the ordinary pressure. Air in motion cannot properly be said to have any more pressure or tension than the still air through which it moves. What would otherwise be extra pressure is real- ly converted into motion in the air. Any excess of pressure really existing is simply that due to the friction which the air en- counters in moving. This is a fact not always understood, and not always ac- knowledged, even in works pretending to treat the subject upon scientific prin- ciples. Force may be converted into mere motion without at all increasing the tension or spring of the air to which it applied ; if it does increase the pres- sure on the air, it is only to the extent of the resistance encountered. Air in mo- tion is called et wind ;" and owing to its inertia it will only lessen its speed by meeting with fractional resistances, or by giving out its force to obstructions, such as the surface of the earth, houses, trees, wind mills, and other objects ; and in every case where power is taken out of the wind, it is done at the expense of lessening its velocity. If, for instance, we should make the wind passing through a mine drive a mill, we would thereby lessen the force and quantity of wind cir- culating in the mine, in a given time, if the pressure causing ventilation remained constant. Railway trains, at high speed, even in a calm, meet with a large share of their resistance from the air — the trains lose force, and the air gains what they lose. Owing to the inertia of the air, birds meet with such a resisting medium in it as to give them a fulcrum, or rest- ing place, for their wings, and enable them to fly. This property of inertia be- longs ^ alike to all material bodies, and may, in general terms, be called an un- willingness to move, when at rest, or to change their speed or direction of motion when they are moving, without a force or resistance being applied to cause them to do so. Air is compressible. Air is squeezed and contracted into less and less bulk as we increase the pressure upon it. If we double the pressure (without chang- ing the temperature), the same air only fills one-half of the space ; if we treble the pressure, it only fills one-third of the space ; and if we apply four times the pressure, it only fills one-fourth of the

space, and so on, provided that the heat or temperature of the air remains the same. This is called the law of Mar- io tte, or Boyle. The air at the surface of the earth is generally pressed by the whole of the air above it, to an extent measured by 29.922 inches of mercury (reckoned at the density due to melting ice, 93°), as shown by our common baro- meters ; a pressure equal to 2,116.4 lbs. per square foot. To give this pressure we should require the air of the atmos- phere to be 26,216 feet high, if it was all as heavy as the air at the earth's surface. The fact is, however, that the air, as we go up, is pressed by less and less air above it ; and owing to its elasticity, or spring, becomes lighter and lighter, so that instead of 26,216 feet, or nearly five miles high, the atmosphere is immensely higher. It gets so much thinner, rarer, or lighter, that at —

Z)4 miles above the surface of the earth it is —

2 tim es rarer 7 " "4

14 " " 16

2; ,< .< 64

28 " " 256 "

35 " " 1,024 "

And so on. If we carry a barometer up a hill, we have less and less air above us. and its pressure will, therefore, support less and less height of column of mercury, and hence the barometer falls. If we take it down into a mine, we get a longer col- umn of air above us, and it supports a longer column of mercury, so that the barometer rises. In ordinary states of the weather mercury is about 10,800 times as heavy as the same volume of air near the surface of the earth, and hence about 900 feet, or 150 fathoms, of ascent or descent, makes a change of one inch of mercury in the height of the barometer. This fact has been applied to measure the height of mountains by means of baro- meters, and it has sometimes been em- ployed to estimate the friction of air in shafts. The difference between the height of the barometer at the top and the bot- tom of a pit 150 fathoms, or 300 yards in depth, is about one inch of mercury.

Air is elastic ; it is a perfect spring, so that whatever force compresses it is an exact measure of the force it will spring out with, if we take away the compressing force. The air, at the surface of the earth, is pressed at about 14.7 lbs. per square inch, and if we take half this pressure

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off, it will swell out to twice its previous bulk ; if we take away three- fourths of this pressure, and only leave one-fourth, the same air will swell out and fill four times the space it previously occupied, and so on. Whatever force or power is expended in compressing air into less bounds, will be given out as force or power by the same air, in swelling out to its former volume, when we take away the pressure so applied.

Air has weight, like all other material bodies. The weight of a vessel filled with air is greater than its weight when the air is pumped out of the vessel. A tall column of air, one foot square, and of the full height of the atmosphere, weighs nearly one ton. Another column of the same height, and one inch square, weighs rather more than fourteen pounds. The weight of the atmosphere enables it to support a column of water nearly 34 feet high, or one of mercury nearly thirty inches high ; and this pressure acts equally in all directions — up, down, sideways, and in fact, in every direction. The body of a man of average size is pressed by nearly thirteen tons weight from this cause.

The direction, speed, and force of the wind depend upon the amount of the difference of pressure that gives rise to it, and, in general, has little or no connec- tion with the gross amount of the pressure acting in the direction of the wind ; be- cause a large share of that pressure is counterbalanced by an equal pressure, acting in the opposite direction.

In the open air the velocity of the wind is the same as the velocity that a body would acquire by falling from the top to the bottom of such a column of air of equal density as, by its weight, would produce the same pressure as that which gives rise to the wind. For in- stance, if the state of the air, as to the temperature and pressure, is such that there is a pressure of 2,000 lbs. (which is nearly a ton) on each square foot, in one direction ; and only 1,999 lbs. per foot, or one pound per foot less, in the opposite direction, when thirteen cubic feet of air weigh one pound, then the difference of pressure giving rise to the wind is equal to one pound per square foot ; and a column of air, one foot in area and thirteen feet high, would weigh one pound. But a body falling through a height of thirteen feet, under the force of

gravity, would acquire a velocity of 8.02; times the square root of 13, or 28.9 feet per second ; and this is, therefore, the velocity of a wind in the open air, due to= a pressure, or rather, to a difference of pressure of one pound per square foot, when the total pressure of the atmos- phere is nearly 2,000 lbs. per square foot, and thirteen cubic feet of air weigh one pound. If we wish to find the velocity of such a wind in the open air as is due to a known difference of pressure on each square foot, we have, first, to find how many cubic feet of the air is equal in weight to the difference of pressure on a square foot, which gives rise to the wind ; and eight times the square root of this number is equal to the velocity of the wind, in feet per second. In like man- ner, if we would find the pressure giv- ing rise to a wind, when we know its, velocity, we must square the velocity in feet per second, and divide the result by sixty-four and one-third, and the quotient will be the height in feet of an air column, giving rise to the wind ; this height be- ing divided by the number of cubic feet, of air weighing one pound, will give the difference of pressure in pounds per square foot, giving rise to the velocity. This rule is merely the s reverse of the former one. A difference of pressure of only one pound to the square foot, under the conditions before stated, gives rise to a wind in the open air, having a velocity of 28.8 feet per second, or more than nineteen miles per hour, which is nearly equal to the highest velocity of the air in the upcast shafts of coal mines.

In practice, in the ventilation of mines, it is found to be necessary to employ a very much higher pressure than one pound to the square foot, in order to give rise to this velocity ; it is, indeed, in many instances, necessary to employ from ten to twenty pounds per square foot to do so, and this pressure is equal to the weight of an air column 130 to 260 feet high, instead of only thirteen feet high as in the open air. It has been a very common mistake to consider that this dif- ference shows a discrepancy between theory and practice ; it shows no such thing. The true theory of any subject- embraces in its grasp all the causes that operate, and can never fail to agree with, practice — if it is really the true and com- plete theory. Theory, indeed, is a col- lection of general principle?;., gleaned or

GASES IN COAL MINES.

2T

generalized from observation of the re- sult of practical trials or experiments ; and it is either a false or an incomplete theory that does not embrace the whole of the general principles involved in any phenomenon we may observe. It would be true, and therefore much more be- coming, in such cases, to say that we do not understand the true theory, because the hypothesis or supposition we have adopted does not agree with what we notice to occur in practice ; and this ought to set us to work to try to find out what is the true theory of the matter; be- cause practice, when not guided by gen- eral principles, is mere guess-work, or empiricism, so far as regards every case excepting only that in which the observa- tion itself is made.

The reason of from ten to twenty times the amount of force or pressure that is required to generate any velocity in the open atmosphere, often being required to give rise to the same velocity in the air in mines, arises from the friction that air meets with, by rubbing against the sides of the air-ways, in passing through mines. Every square foot of surface ex- posed to the air travelling along the gal- leries of a mine is pressed by the air to the extent of about a ton of force or pressure, and it is, therefore, no wonder that extra pressure is required to over- come the friction arising from this im- mense pressure. If, for instance, we find that the last or final velocity of air escaping from a mine, by an upcast shaft, is such as to require a pressure of one pound per foot, or thirteen feet of air column to give rise to it, on the supposi- tion that there were no friction ; and if, at the same time, we find that the actual pressure employed is ten times as much, or ten pounds per square foot, we learn from this, that nine pounds out of the ten pounds per foot are required to over- come the friction of the air in rubbing against the sides of the air-ways ; the other one pound per foot, or one- tenth of the whole pressure only, being re- quired to give rise to the velocity ; and this is no uncommon case in the practice of the ventilation of coal mines. Fric- tion, then, arising from the air rubbing against the top, bottom, and sides of the air-ways in mines, is really the greatest obstacle to be overcome by the ventilat- ing pressure or power ; the force required to put the air into motion, apart from

friction, being very small in comparison, at least in a large majority of cases, par- ticularly in coal mines, which generally require a much more energetic ventila- tion than is necessary for the salubrity of metallic mines.

To show the comparative amounts of pressure expended upon creating velocity in the air, and upon overcoming the frac- tional resistance it meets with in mines, respectively, the following cases are cited, the pressures due to velocities being those due to the final velocities at the tops of the upcast shafts.

	5	1 Kg	s	5
	«SSf	Cfc 5o 3-5	■« 8. : * : i : 1	: §§* : g-a>
	! §	: 9			§ ®"
	: £ : s	• § : 3	\|\|		-5 "t- Cfc (V
	Feet.	Feetb	Feet.	Feet.
Hetton Colliery, 1st. case...	10-43	179-8	190-31	1 : 18
Do. Do. 2d case. . . .	12-37	212-63	225-00	1 : '7
Haswell Colliery	13.84	140-66	154-50	1 : 10
Tyne Main Do	25.70	177-50	203-20,	1 : 7

From this it will be seen, that out of a total pressure of nineteen, at Hetton. Colliery, no less than eighteen were em- ployed on friction, and only one upon, the velocity of the air.

At Haswell Colliery, ten parts out of eleven of the ventilating pressure were spent upon the friction of the air ; and. only one part out of eleven upon creat- ing its final velocity at the top of the up- cast shaft.

At Tyne Main Colliery, seven parts out of eight of the ventilating pressure were spent upon friction ; and only one part in eight upon the velocity of the air at the top of the upcast shaft.

From these examples it will be per- ceived that the amount of ventilation in, mines, and, therefore, the safety, health, and comfort of the workmen employed in them, depend almost entirely upon the amount of friction that the air meets with, under any mode of ventilation we may employ ; and hence, the great im- portance of understanding the general, laws and principles upon which the fric- tion of air in mines depends, so that we may know how to reduce such friction to its lowest possible amount, and by this means obtain the greatest quantity of air^... from any ventilating power we may em- ploy.

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TUBULAR FLOATING DOCKS,

From "Naval Science.'

It is quite unnecessary to insist at the present day on the general usefulness and merits of floating docks. The fact that they can be employed in deep water, and in situations where from the nature of the ground it would be impossible to cut docks on the ordinary system, and that too, independently of the height of the tide, is so manifest an advantage that it cannot be questioned that at a time when increased dock accommodation is urgent- ly required their principle will be largely employed. The comparative cheapness of their construction also tells powerfully in their favor. To this must be added the consideration that floating docks are capable of being moved from place to place, so that if the demand for their use be diminished at one port, they can readily, and at small expense, be moved to another where the demand is greater; while from their comparative cheapness they can at all times be more profitably employed than fixed stone docks which have been built at a large outlay. The story of the great Bermuda dock built for the Government by Mr. Campbell, and safely towed across the Atlantic without accident or unusual difficulty, must be fresh in the memory of all who take an interest in shipping, and affords a memorable example of the truth of our observations. Floating docks of the or- dinary type consist, as is well known, of parallel or nearly parallel walls terminat- ing in a flat bottom, the space between being divided into a large number of water-tight compartments, into and out of which water may be pumped by means which need no description, and so may be raised or lowered at pleasure; so that vessels of various sizes may be received on to the dock, and then raised by pump- ing the water out until the workmen can obtain access to the whole of the hull, and perform the requisite repairs, and can then be lowered by admitting the water until the vessel can be floated off.

Messrs. Clark and Standfield's Patent Tubular Dock is of a totally different construction, and is worked in a different manner. Both the bottom and the ver- tical sides of their dock consist of a

number of circular wr ought-iron tubes similar to egg-ended steam-boilers. The bottom of the dock is formed of about eight circular tubes which run the whole length of the vessel and extend some feet beyond its ends. These tubes are stiffened inside by angle irons every two or three feet, and are securely braced to- gether by transverse beams of T and angle iron above and below, which are so united by the tubes themselves and by gusset-plates as to form transverse gird- ers of ample strength to support the platform, having sufficient buoyancy to support both the vertical sides of the dock and the vessel itself.

The sides of the dock are also formed of similar tubes which are fixed vertical- ly. Each side is formed of from twelve to twenty-four of these vertical tubes, which are inserted upon the two outer longitudinal tubes, and attached by flanges like the dome of a steam boiler; the vertical tubes are braced together and connected by a lattice-work platform at the top running the whole length of the dock, forming a spacious gangway for the workmen. The longitudinal tubes are continuous throughout, and by means of the side tubes and braces they are so connected with the iron platform at the top as to convert the whole dock into a beam or girder of great depth and of immense rigidity. The centre longitu- dinal tubes are considerably larger than the side tubes, so that the general plan of the dock resembles somewhat that of an ordinary vessel. The two outer tubes are of larger diameter than the others, so as to give extra stability of flotation, and to afford convenient attachment for the side tubes.

The tubes are divided within into a great number of water-tight compart- ments or chambers connected together by pipes, and the raising and submersion of the dock is effected by means of com- pressed air. The base of the dock is di- vided into about sixty air-tight compart- ments, separated by egg-ended bulk- heads, and the vertical sides form about forty additional chambers, and the whole of these last are hermetically sealed, so

TUBULAR FLOATING DOCKS.

28?

that the dock cannot under any circum- stances sink. A certain number of the bottom chambers are so hermetically sealed ; but the remainder are provided with valves at bottom which can be opened or closed at pleasure, and with wrought-iron pipes which are grouped together, and are all brought to a valve- house on the top platform of the dock, and are placed under the control of the valve engineer. When it is desired to sink the dock the bottom valves are all opened, and the air allowed to escape at the valve-house until the dock settles down to its lowest level ready for the re- ception of a vessel. When it is desired to raise the dock, air is forced into the tubes under compression, the water is ex- pelled through the bottom valves, which are closed as soon as the dock and its vessel are fully raised; it then remains afloat with the vessel docked upon it, without any dependence on the air- velves.

The engines are in two pairs, placed near the centre of the dock within the vertical tubes, the main from these being led into the valve-house. The whole of the water-tight compartments in the bot- tom are divided into four equal groups corresponding with the four corners of the dock by means of four correspond- ing valves in the valve-house; air is ad- mitted into or out of these respective groups in any desired proportions, so that the dock is maintained at all times perfectly level both in raising and lower- ing.

This novel form of dock has, to a great extent, the combined merits of the stone graving dock, and of the ordinary hy- draulic lift or pontoon dock, together with some advantages which are peculiar to itself. It has immense stability, owing to its great breadth, and to the great number of compartments into which it is divided, which prevent the tendency of the water to flow to the lower side — a tendency which may be, moreover, cor- rected at any time by allowing the com- pressed air (which is always kept stored in the vertical tubes) to act temporarily on any of the compartments. It is pro- vided with sliding bilge blocks, similar to those used on hydraulic graving docks, which are drawn under the vessel by chains. The vertical tubes are also well provided with side frames affording facili-

ties for side-shoring similar to those of stone graving docks, so that even loaded vessels may be readily blocked and shored up to any desired extent ; this is a point of great importance in the lifting of heavy iron-clads, and, moreover, by ad- mitting water into some compartments and expelling it from others, the lifting- power can be to a great extent exerted directly under the load to be lifted. The vessel when lifted is high and dry above water, an advantage common to all float- ing docks, but owing to the vertical tubes in this dock being well separated from each other, there are great facilities of access to all parts of the vessel. Two large gangways of extra width, provided with cranes, are also formed at each side for the landing of heavy timbers, plates, &c. The open sides admit of the air and light circulating freely round the work,, so that paint dries and hardens much more quickly than in a sunken dock. From the same cause repairs can be ex- ecuted in a much more prompt and satis- factory manner than in a stone dock.

The tubular form not only possesses great structural strength, but is peculiarly suited to withstand the extreme pressures to which floating docks are necessarily subjected both externally and internally. When an ordinary dock is submerged in deep water the air compartments have ta withstand an external pressure of, say,, fifteen or twenty pounds on the square inch, tending to buckle the plates and open the joints ; to make these compart- ments square and flat' is as great an error as it would be to make a square steam- boiler or square iron pipes ; in either case heavy and costly struts and ties are neces- sary to preserve the form and prevent bursting or collapsing. In the circular form, on the other hand, the material is- in perfect equilibrium, and its whole ten- sile or compressive strength is directly exerted in withstanding the pressure. It is well known, too, that the circular form offers facilities for caulking which are not possessed by flat boiler work. The tubes are accessible all round within and without for cleaning and painting, and by an ingenious system of canting the under sides of the tubes are made acces- sible for cleaning and repair. From the great number of compartments into* which the dock is divided it seems scarce- ly possible that it could be dangerously

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injured by shot or collision ; it is stated, indeed, that if three-fourths of the com- partments were punctured the structure would still float.

In exposed positions it is proposed to submerge the dock entirely whenever it appears to be endangered by a cyclone or by stress of weather. The tubular sides afford great facilities for this opera- tion ; compressed air is pumped into them at leisure and kept stored up ready for use ; after the dock is submerged the opening of the valves will at any time allow it to expand and raise the dock to the surface. This use of stored-up power is also employed whenever it is desired to raise vessels rapidly — as, for example, in examining bottoms or screws; the power being stored up and ready for use, the docking of a vessel occupies but little time; by opening communication with the water in the tubes the air expands .and expels the water and the vessel is immediately raised.

The dock can, of course, be used in conjunction with flat pontoons for float- ing vessels, as is now done with the hy- draulic lift-dock, and the combined lift- ing power of the dock and a tubular pon- toon is obviously much greater than that of either of them separately. The pon- toons being perfectly water-tight are well adapted for withstanding a sea passage, and for conveying vessels over bars or shallows, after which they can be lowered into deeper water. It is proposed, in fact, to fit these pontoons with engines and screws, and their tubular form would enable them to pass through the water with little resistance.

Not the least among the advantages of the tubular form of dock is the fact that owing to the small amount of interior strutting required, and the great sim- plicity of its construction, it can be put together in a much less time than an ordinary dock, and with a much smaller quantity of material, and consequently at a very greatly reduced cost.

The floating dock appears to occupy an intermediate place between the old stone graving dock and the hydraulic lift- dock. Where the number of vessels to I>e lifted is very great, preference will probably be given to the latter ; but the floating dock has advantages of its own. In the first place, its greatly reduced cost renders it suitable for many positions in

which the business is sufficient to warrant the cost of a stone dock or an hydraulic lift dock. There are several cases in which floating docks of the ordinary con- struction are paying dividends of 20 or 30 per cent., in positions in which stone docks would be impossible, or in which their cost would entirely preclude their adoption. It is not always easy to find a suitable position for an ordinary grav- ing dock, and even the hydraulic lift sys- tem requires water of a certain limited depth ; but a floating dock can be placed anywhere where there is sufficient depth for a vessel to approach, and can be trans- ported from place to place.

It has been stated that the tubular dock is raised and lowered by pneumatic means ; there is, of course, no theoretical reason why it should not be worked by ordinary water-pumps in the usual man- ner. The practical objections to the sys- tem are, that either the dock must be divided into a very few water-tight com- partments, in which case it is somewhat unstable, owing to the tendency of the water to flow into the lower compart- ments ; or else if divided into a sufficient number of compartments the size and weight of the large cast-iron pipes and pumps required for exhausting the water bear a very serious proportion to those of the dock itself, and add materially to its cost.

In pumping air small wrought-iron pipes are sufficient, and the engines may be of the slightest construction and worked at the highest speed without risk of damage, while it is at the same time possible to store up a certain por- tion of the air in a compressed form in the vertical tubes, which form a large reservoir of power which may be accu- mulated at leisure and employed at any moment required. When it is desired to lift a vessel in a moving sea this stored- up power may be of great importance, for as soon as a vessel is placed in proper position in the dock it is desirable that she should be at once partially litted so as to secure her temporarily while addi- tional shores and bilge blocks are being fixed.

Floating docks appear likely to be ap- plied in future to another purpose to which sufficient attention has hitherto not been drawn, We allude to their employ- ment as building slips for the construe-

VESSELS OF WAR.

31

tion or lengthening of vessels. On the ordinary system it is necessary that a buil ding-yard should be closely adjoin- ing deep water, and that the vessel should be constructed and launched on inclined ways, a process not always devoid of risk. By building on pontoons this risk Is almost entirely avoided ; any shallow river or creek may be utilized, whatever its distance from deep water, and the ways may be laid on a pontoon either floating in shallow water or resting on the ground in a shallow dry dock tem- porarily prepared for the purpose ; and when the vessel is ready for launching, the water may be admitted to the dock, the valves closed, and the vessel floated out into deep water. During the opera- tion of submersion it is necessary that the pontoon should have vertical sides, in order to insure stability at the point of time when the vessel first begins to take the water, and before she is fully water- borne. In a large building-yard these vertical tubes might, however, with ad-

vantage be only fixed temporarily in seg- ments, and removed and applied else- where while the pontoon was being used for building a second vessel. A similar arrangement might be employed for lay- ing up gunboats and other vessels in or- dinary while out of service. A shallow dry dock would contain a large number of such vessels, all parts both of the pontoons and vessels being accessible for painting, while the admission of water would enable the whole at any time to be floated out and submerged ready for use. In fact, floating docks have not yet as- sumed their proper place in the naval service. Constructed often in a tem- porary manner of wood or iron, and from imperfect designs, they have sometimes met with indifferent success or even with disaster ; but experience has shown at once both their defects and their merits, and there is no doubt they are destined in future to become one of the most im- portant elements both in navigation and in naval construction.

VESSELS OF WAR.

BY ISAAC NEWTON, C. E. From the New York " Times."

Nevee before was the whole subject of marine warfare in such a muddle as it is now. When Louis Napoleon launch- ed the Gloire, fifteen years ago, he open- ed a discussion which seems never likely to come to an end. The European navies had settled down to what they supposed was a sort of " hard-pan." After more than a decade of talk and experiment they had finally got the screw fairly in- troduced, and the batteries were gener- ally equipped with shell guns. The de- struction of the Turkish fleet at Sinope by the Russian shell-guns and time-fuses, in the early part of the Crimean war, sent a shudder through the naval circles of Europe. The alarm was as to the then existing power of naval batteries. If the small shell-guns of the Russian fleet did such swift execution, what would be likely to happen if ten-inch shells were fired into one another's vessels ? One or both of the antagonists must forthwith be sent to destruction. The standard authority on naval gunnery referred with korror to the awful power of this tremen-

dous missile. It was this fearful antici- pation, as much as the launching of the Gloire, that gave birth to the iron-clad era. That these anticipations were en- tirely justifiable the fearful carnage which the shells of the Mcrrimac in a few min- utes inflicted on the Cumberland and Congress is abundant proof.

It was at this time, in 1861, that the Monitor made its appearance. England had already begun her iron-clad navy, and had launched the Warrior, the BlacJc Prince, the Defense and another. The French had built a companion to the Gloire. The fight between the Monitor and Merrimac changed the whole aspect of things. Foreign powers saw that wooden ships had no show against shell- guns in shot-proof vessels, and that we had been able to build within a hundred days a ship that solved the iron clad problem, and was capable of sinking any French or English wooden ship that might come against it. The fact too was apparent that a few months would give us a fleet of just such vessels. And in a

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few months we had the fleet. But we [ have made no attempt since the war to j compete in iron-clad construction with England and France or any of the Euro- pean powers. We have practically ceased to place reliance on guns for the defense of our harbors. Our course now is plain. It is to attack an enemy below the water- line— abandoning all devious attempts to overcome his armored sides — and thus to neutralize whatever advantage he may have obtained by colossal expenditure on iron-clads.

The fact that attack below the water- line by subaqueous weapons is destined to utterly revolutionize naval warfare would seem to be too plain to require la- bored demonstration; but undoubtedly another great war will be needed to con- vince naval authorities of it. England, France, Germany, and Russia vie with each other to produce an iron-clad abso- lutely impregnable to existing artillery. England has just put the monitor Inflex- ible on the stocks. She is to have twenty-four inches of armor on her tur- ret, and is to carry guns firing shot weighing 1,200 pounds. Russia has launched the Peter the Great, and Ger- many follows with her Frederick the Great. Meanwhile, the naval writers of Europe are filling newspapers, magazines, and pamphlets with discussions and con- troversies as to the general character and powers of iron-clads, and, strangely enough, naval officers are preparing elab- orate treatises on naval tactics for the disposition of these monsters, as if they were to be handled and manoeuvred as Von Moltke could an army corps on a smooth plain. Inasmuch as a few hun- dred pounds of nitro-glycerine, or some other of the modern explosives, fired in

contact with their unarmored sides below the water, would send the strong- est of these naval giants to Davy Jones's locker before even the sim- plest of " naval tactics " could be put into operation, we must regard the work of these industrious tacticians as thrown away.

The inability of the naval specialists to appreciate the situation, and the conse- quent muddle that exists throughout Eu- rope as to models of vessels, the charac- ter of armor, the purposes to which naval vessels may be put, and the methods of naval warfare, are indications of the com- ing revolution. To show the extreme to which they go, we find little kingdoms like Sweden and Norway building an in- significant number of broadside iron- clads, thus feebly following in the wake of Russia and Germany. Of course, these vessels are of no use to such a power for offensive purposes, and as for defensive purposes they are worthless,, and their whole construction is simply a frivolous waste of money, prompted by vanity and a foolish attempt at rivalry. It is hard for the naval minds to under- stand that the old ideas of naval power are fast approaching an end. A clear ob- server, informed as to the situation, must recognize the fact that twenty-five years from now a navy will exist only as a means of defense for the great nations. The vast sums that are spent every year in maintaining and increasing the navies of Europe on their present system may, therefore, be regarded as practically thrown away. The comparatively inex- pensive submarine monster, applied to defensive uses, will neutralize all the mil- lions that are now wasted on enormous naval constructions.

A Wooden Railroad in Michigan. — The tram road of Van Etten, Kaiser & Co., at Pinconning, Bay county, Michi- gan, is 11 miles long, and is thus described in a communication to the Chicago Hail- road Gazette : There are first logs 12 to 16 feet in length laid crossways about five or six feet apart. Then gains are cut in the logs and flatted timber laid in these gains ; this prevents the road from spreading. Our rails are of hard maple. Before spiking the rails down we put ties across the stringers, notching the stringer

enough to let the tie down even with the top of stringer and spike the tie fast be- fore the rail is laid on. The ties are of two inch hemlock plank from 6 to 12 inches wide ; this prevents the stringer from rolling. We would recommend any one who wishes to build a road on the above system to build it as straight as possible. We have been obliged to dis- pense with wooden rails on the curves and lay down iron. We operate our road with locomotive power. Cost of building without rolling stock is $2,000 per mile.

THE WARNER PROCESS.

33

THE WARNER PROCESS.

From. " The Engineer."

Since Cort invented the process of puddling in 1784 the substantial improve- ments which have been effected in the method of converting cast iron into wrought iron have been very few. The Bessemer and Martin system revolution- ized the steel trade, but nothing analo- gous to the Bessemer or Martin process in its effects on a great industry has been introduced in the production of wrought iron, and this notwithstanding that le- gions of inventors have spent time and money in attempting to solve an appa- rently unsolvable problem. If the rotat- ing puddling furnace can be made a sub- stantial commercial success, then it is more than probable that Cort's invention will be superseded after nearly a century of use. But we cannot regard any sys- tem of mechanical puddling yet pro- duced as perfectly satisfactory ; and even though this were not the case, there is reason to believe that other systems of purifying cast iron might be adopted either alone or in conjunction with a me- chanical puddling furnace with advan- tage. We regard therefore with inter- est every attempt which is made to su- persede or supplement the ordinary sys- tem of hand puddling, and we have at all times endeavored to put the claims of inventors in this branch of science fairly and dispassionately before the world. In this spirit we now desire to «all the attention of our readers to a novel method of manipulating pig iron, which, judging from the evidence laid before us, has proved unusually success- ful as compared with the results ob- tained by other processes intended to effect the purification, wholly or in part, of cast iron. The inventor of the new process is Mr. Arthur Warner, of Lon- don, and it is the result of many hun- dreds of experiments, carried out under the supervision of Mr. Warner's son, a competent chemist, and at very consider- able expense. The process in itself ex- erts no small claim on our favor in that it does not attempt too much. Mr. War- ner does not profess — as too many invent- ors do — to produce a perfect material from an inferior pig at an impossible cost. He has addressed himself to a specific Vol. XII.— No. 1—3

object, and we have the testimony of many practical men to prove that he does really effect what he professes. Besides this, there is about the Warner process a definite promise and foretaste of the suc- cess in that he does not work with infini- tesimal quantities of "physic," and that he can give a sound chemical reason for everything that he does. The thing is so simple that it admits of being ex- plained in a few words, but the reactions on which its success depends require a little explanation, which we shall give before going further.

It is well known that the two princi- pal ingredients in pig iron which the op- eration of puddling is intended to remove are carbon and silicon. With two other impurities — sulphur and phosphorus — the puddling furnace deals with doubtful effect. What carboa is we need not stop to explain. Silicon, or silicium, as it is sometimes called, is a peculiar non-me- tallic element, which, in combination with oxygen, constitutes silica. It is present in cast iron in various quantities, from 5 or 6 per cent, downward : less than 3 per cent is comparatively rare. Why the presence of carbon and silicon, except in very minute quantities, should be inimical to the existence of wrought iron, is not very clearly understood. Even though it were, we should not di- gress to deal with fhe question here. The broad fact remains that the carbon and silicon must be got out of the pig be- fore we can have wrought iron. As it is not necessary to plunge very deeply into I the chemistry of the subject, it will be enough to state that certain materials exist which have the power of combining with silicon and sulphur under the influ- ence of heat, and of producing with them a slag or cinder which is lighter than iron and is fluid at the temperature at which iron melts. One of these materi- als— to select the cheapest and best known — is limestone. This is used in the blast furnace, and disposes of a large proportion of the silicon and sulphur con- tained in the ore. But the quantity of limestone which can be used is limited because it tends to produce '; scaffold- ing " and to " gob " the furnace. If more

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could be used, the resulting pig would be purer; as it is, in practice we have vary- ing quantities of silicon in the pig, which must be subsequently removed. Now fully impressed with the importance of the part played by limestone in the blast furnace, and knowing the advantage which would be gained — and to which we shall refer presently — by getting rid of the silicon and sulphur, Mr. Warner labored to effect the removal of both by a further use of limestone. His process, therefore, it will be understood, differs from almost all other chemical processes, so called, of purifying iron, in that it leaves the carbon untouched and deals with the silicon and sulphur alone. Mr. Warner first attempted to effect the re- quired object by placing a quantity of }30wdered limestone at the bottom of a deep and narrow vessel and pouring cast iron on the top. The process was a com- plete failure ; the limestone caked to- gether into a mass under the influence of heat and remained at the bottom. Mr. Warner overcomes this difficulty in a sin- gularly elegant way. He mixes his pow- dered limestone with soda ash, and places them at the bottom of the puri- fier. As the soda ash becomes heated it melts down and leaves the particles of infusible limestone free. These being lighter than the cast iron, float up through the metal, and become converted into carbonic acid and calcium. The first seizes on the silicon and oxidizes it, becoming itself converted into carbonic oxide, which escapes at the surface of the metal. The sulphur is also attacked and eliminated. In practice the operation of purifying occupies about half an hour or a little more, and during all this time the metal boils violently in consequence of the partial combustion of the silicon and sulphur, and remains perfectly fluid with- out any extraneous heat. In this a re- semblance will be traced to what takes place in the Bessemer converter, but the temperature in the Warner purifiers is so much less, that ordinary fire-bricks can be used instead of ganister as a lining. In brief, then, the Warner process con- sists in placing at the bottom of a wrought iron cylindrical vessel, six or eight feet deep and two in diameter in- side the fire-brick lining, a given quan- tity of pulverized limestone and soda ash, .and pouring on this from two to ten tons

of melted iron either from the blast fur- nace or the cupola. When the process of purification which we have described is concluded the metal is tapped out into cakes or pigs. The slag is then tapped off, and the purifier is ready for an- other charge. In order that no doubt may remain as to the precise nature of the process, wTe publish Mr. Warner's specification on another page. To use the inventor's own words, uThe process is carried out in the following manner : A cylindrical plate iron vessel with fire-brick lining, mounted on wheels, and capable of holding five to ten tons of iron, is run up close to the blast furnace and under a chimney to carry off the gas and flames. At the bottom of this vessel has been previously placed the required quantity of the purifying mixture. The iron is then tapped from the blast furnace and runs into the vessel upon- the top of the powder. A violent action begins at once, and lasts for twenty or thirty min- utes. The carbonic acid, by the oxida- tion of the silicon, becomes converted into carbonic oxide, and burns at the top of the chimney with an intensely brilliant flame, colored yellow by the soda. As soon as the agitation ceases the vessel is drawn away from the blast furnace and tapped into iron moulds. The silicon and sulphur, in combination with the lime, then follow as separate slags free from iron, the carbon being increased or decreased as required." The product thus obtained is a white refined iron, practically free from silicon and phospho- rus. We select a single analysis by Mr. Riley from many to show the result of the operation of the process on Cleve land pig: Combined carbon, 3.218 ; sil- icon, 0.012; sulphur, 0.092 ; phosphorus, 1.750. The original pig iron contained over 3 per cent, of silicon.

To convert the refined metal thus ob- tained into wrought iron it is puddled in the ordinary way as refined iron ; but it is found in practice that owing to the re- moval of the silicon and sulphur alone the iron will — unlike ordinary refined metal — boil freely, and become quite fluid. The duration of the puddling pro- cess is also much reduced, so much, in- deed, that at the Kirkstall Forge twenty- seven heats were got out with the aid of a dandy fire in twenty-four hours, in- stead of twelve, the usual number. The

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saving of fuel thus effected is obvious, ! but the reduction in the quantity of fet- j tling required is also very considerable, for reasons which will be too readily un- ; derstood to need explanation here.

So far we have said nothing as to the ' removal of phosphorus; and as to the success of the process in this respect we i shall pronounce no opinion for the present. | Mr. Warner claims to remove phosphorus j altogether in the subsequent process of j puddling by the use of plenty of hammer slag, and he argues that phosphorus is not got out in the ordinary process of puddling only because the silicon present iu the iron seizes on the oxygen in the fettling and hammer slag, and renders them so inert that they cannot touch the phosphorus. As his refined iron contains no silicon, the oxidizing agents are free to deal with phosphorus, and do deal with it accordingly. As we have said, Ave shall pronounce no decided opinion on this theory, but we may state that Mr. Warner has supplied us with evidence going to prove that from some cause or other very little phosphorus indeed is to be found in puddled bars of his iron.

It will be seen that the process we have just described is very similar to many others up to a certain point, but the essential difference between it and such processes as that of Henderson is that a great depth of metal is superim- posed on the purifying agents, and that no extraneous heat of any kind is em- ployed while the process is proceeding.

As regards the practical results obtained by Mr. Warner, we cannot have better evidence than that supplied on oath be- fore a Judicial Committee of the Privy Council engaged in deciding Mr. War- ner's claim for an extension of one of his earlier patents. Mr. Lee, of the Gospel Oak Works, tested about 20 tons of Warner refined metal made from Cleve- land pig, and stated that he found it equal to all mine Staffordshire pig, and worth twenty shillings a ton more than ordinary Cleveland iron. Mr. Barrett, of the Kirkstall Forge, having tested the iron, ordered 500 tons of it, at twenty shillings advance on Cleveland pigs, while the testimony of Mr. Hall, Mr. Whitehouse, and others is equally favor- able to the process. We cite this evi- dence simply to prove that the favorable opinion we have expressed concerning the process, although based on the chem- ical theory involved, is supported by the results obtained in actual practice, as tes- tified to by men of immense experience and sound judgment. We may state im conclusion that Mr. Warner is, we be- lieve, now making arrangements for the> erection of works on a large scale for the production of refined pig, so that the ques- tion of the commercial value of the pro- cess will soon be set at rest forever. We have no hesitation in admitting that the process appears to us to possess more promise of complete success than any other which has been brought before the world since Mr. Bessemer made steeL

TRIAL TEIPS.

From " Engineering."

Engfneeking is essentially an experi- mental science. The mathematician and }Dhysicist discover and elucidate its laws and first principles, but are able within the limits of their own sciences only to apply those laws and principles to structures existing upon paper. The varied conditions under which the actual structures have to be erected and worked, or used, are such as they cannot within those limits take into account. In their investigations they have, for instance, necessarily to assume the perfect rigidity of various joints and fastenings the na-

ture and strength of which vary exceed- ingly, and in many other ways to start, with assumptions or hypotheses whieK may or may not correctly represent th& conditions which obtain in practice. It is of the very greatest importance, in or- der to the growth of scientific engineer- ing, that the class of scientific investiga- tors to whom we allude should have their hands strengthened in every possible way. They are doing for engineering- what few engineers have either time or ability to do for it — investigating and, elucidating the foundation principles oil

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"which it rests, and are putting the com- ing race of constructive engineers in a position to work with some approach to scientific reason and accuracy. It is scarcely necessary to point out that this is not an advance in abstract knowledge merely. It means, in the first place, in- creased safety in structures, and then economy of labor, economy of material, and, in the case of coal-consuming ma- chines, economy of fuel. The applica- tion of scientific principles to the design of engineering work will, in fact, make it safer, more efficient and cheaper at the same time.

The great want of all those who are ©ngaged in the investigation of engineer- ing science at present is experimental ■ctata by which to verify conclusions ar- rived at inductively, and to arrive de- ductively at further conclusions. The olass of experiments which alone can be of much use under present circumstances must be (1) upon a sufficiently large scale (2), carried on as nearly as possible Tinder the conditions obtaining in actual ^practice, and (3) noted completely in all their details. The conclusions derived irom mere laboratory experiments can 'but seldom be applied to engineering- work Experiments, for instance, with propellers 2 in. diameter, or with model ^vessels a few feet long, while interesting in themselves, do not supply us with ■data which we can with confidence apply to 16 ft. screws or ships displacing a couple of thousand tons. The scale Tup.on which the experiments are carried on is not, however, everything. They :may be on a large scale — they may even l>e conducted with full-sized machines or structures — and yet be of comparatively little use. This occurs when they are carried out with a view to establishing • certain pre-d et ermine d results, or prov- ing some already assumed economy. In this class come but too many of the pub- lished experiments connected with any mew machine or apparatus, the working of which invariably " exceeds the most sanguine expectations of its promoters." :Such experiments (when the results pub- lished have really been arrived at, and are not, to a great extent, imaginative) are for the most carried on under excep- tional conditions, or for short periods, do aiot represent truly the results which -would be obtained in ordinary working,

and, therefore, cannot be " founded on " by the investigator. It is, of course, true that it is important to know the very best results that can be obtained from any piece of apparatus, as well as its average efficiency ; but for this purpose it must be stated in the account of the experiment whether the conditions under which it was carried on were ordinary or special, a little fact which inventors and patentees somehow omit occasionally to mention. The statement that experi- ments to be of value should be complete, will awaken responsive echoes in all the army of investigators, who have spent hours — or perhaps even days — wading through masses of ill-arranged informa- tion in hopes of arriving at length at the one little fact which is required as a key to all the others, and without which they remain almost useless, but which, some- how, the experimentor (no doubt a " practical " man) had entirely forgotten to state.

There is probably no section of en- gineering science of greater national im- portance to this country than what may be called marine engineering, embracing the science of naval architecture, and the designing of engines and machinery for the propulsion of vessels.* There is at the same time no section of engineering work in which so many experiments are made ; and yet out of all these experi- ments very few are of real use, even to those who conduct them, and not one in a hundred is of the slightest value to the rest of the world, including the hungry little army of investigators already men- tioned.

Who does not know by heart the or- dinary " Trial Trip ?" and what marine engineer, whose interest in his profession leads him to examine a little below the surface, has not attended trip after trip in the vain hope that he might obtain some valuable data, and again and again come away disappointed and savage? Not a few of our readers must have experienced something like this: The tug has conveyed a crowd of gentlemen (and ladies) to the ves- sel, the anchor is weighed, the engines begin to turn, and a second inspection of the engine-room from the skylight show- ing that the preliminary confusion and crowding below has somewhat lessened, you descend to see what is going on.

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Here too often you find things as dirty and confused as if the voyage were fin- ished instead of begun ; but let us sup- pose that it is intended to take adventur- ous ladies down to admire the " things like spiders," and that consequently all the machinery is tolerably clean and bright. The indicator gear is ready, al- though the lead of some of the strings is not very good ; but a moment's inspec- tion shows that no arrangements have been made for measuring the water that is collected from the jackets. You go in- to the stoke-hole, and there find two or three large, and of course unweighed, heaps of coal upon the floor, and the bunker doors open ; and on looking at the steam gauge you see that the pres- sure is 10 lbs. or 15 lbs. lower than that at which the boilers were intended to work. For an hour or so the course down the river is much impeded by the numerous craft, but at length the water is clearer, and the order for " full speed ahead " is given. Another visit to the engine-room shows you two indicators in place, and you find that no more are forthcoming, and that the cards will be " quite near enough " taken in this way. The first diagrams are not very satisfactory — the instruments cold perhaps — and just as another set is being taken a bearing be- gins to heat, and with much spluttering and splashing the engine is slowed, and the diagrams remain untaken. By the time the brasses have been cooled and eased (if, indeed, the heating does not continue all day), "the mile" is being neared, and great excitement reigns in the stoke-hole, the occupants of which you find to be hard at work under the eye of the manager himself. The throttle valve is wide open, the engines in full gear, water pouring over the offending bearing, and possibly over others as well, and the lads at the indicators working for very life. It is soon over, and when you presently inquire the speed you may probably be surprised to find that the captain's and the manager's statements differ by some thirty or forty seconds, if, indeed, you are fortunate enough to get any definite statements from any one. Then come lunch and the speeches, and, as an invited guest, you feel it w^ould be uncivil to leave the table till they are finished, but you know that the vessel has turned, and that while " The owners" !

or "The ladies" are being enthusiasti- cally toasted you are running the mile iu the homeward direction. At last yon are once more in the engine-room, where you find that various "linked-up " card& have been taken, and that the fuel has been measured for half an hour or so by some method extemporized on the spur of the moment by some well-meanings draughtsman, and found to be at the rata of about 1.5 lbs. per indicated horse power per hour ! Disgust seizes you, and you visit the engine-room no more, but endeavor by the aid of a cigar on deck to quiet your feelings sufficiently to enable you to make the necessary com- monplace compliments to your host be- fore the tug takes you ashore again.

The sum total of the information de- rived from such a trial trip, and we have- really given no unfair picture of trips, that occur every week — almost every day — is this. A vessel of a certain length,, breadth and depth, ran a knot in some- where between five and six minutes on a fine day in a smooth river, and the en- gines indicated at the time so many horse power, actually or approximately. The diameter and stroke of the cylinders,, and possibly the dimensions of the pro- peller and the boilers, constitute with this the whole of the information which any one not in some way officially connected with the vessel is able to obtain, while the engine builders will, of course, know in addition all the dimensions of the vari- ous parts, and (but sometimes only ap- proximately) the hearting and condensing- surfaces. The draught of water has not been observed, or has only been noticed approximately or casually, and the im- mersion of the screw is guessed at. It never enters into any one's head to find out the displacement or the immersed midship section, still less to calculate^ either the actual or the " augmented '* immersed surface. As regards kno wledg e of the laws, or even the facts, of propul- sion, the trial trip is of scarcely the slightest use to the builders of the ship or the makers of the machinery, and of none whatever to any one else.

And yet with very little additional ex- pense or trouble the trial trips, which are- so constantly taking place, might be made to yield information which would be of much direct practical value to the engineer, and would also in the hands of

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scientific men add immensely to our knowledge of all the laws relating to the resistance of vessels. A trial trip might Ibe rendered a complete scientific experi- ment upon the largest scale, and under call, or nearly all, the conditions of actual practice — just the kind of experiment, in fact, which is most urgently needed. The short-sightedness of the system which, partly to save a few pounds and a

little trouble, and partly to make a "vain show," converts atrial into a trip, must be strongly condemned, and we hope that it may not be long before marine en- gineers in general will see with us, that it would be to their interest to do thoroughly and well that which so many of them now expend much trouble in rloing in a useless and incomplete fash- ion.

ON THE ADVANTAGES OF A CONSTANT AS COMPARED WITH AN INTERMITTENT WATER SUPPLY.

From the " English Mechanic."

At the recent meeting of the British Association at Belfast, Mr. Deacon read a paper on his water-waste meter. In the discussion which followed, Mr. F. J. Bramwell, C. E., made some valuable ob- servations. He said : I believe that most serious injury to health has been occa- sioned by the system of cistern storage. Cisterns are of necessity cumbrous. They have to be put somewhere out of the way, and commonly careless or ignorant build- ers or architects fix them in all but inac- cessible places, where they are out of sight and out of mind, and thus attention Is not paid to keeping them clean, and all sorts of filth accumulate ; but, bad as this is, it is not the worst result, of the system, for too commonly the cistern for general purposes is placed in close prox- imity to that part of the house from which it ought on every ground of health and of common decency to be the furthest away, and it appears as though the very effort of the constructors of such houses is to make arrangements for the express purpose of contaminating the water. Those who travel on the suburban rail- ways of London and observe the backs of the poor dwellings in the neighborhood of some of those railways, must have no- ticed that commonly the only cistern was exposed to the full heat of the sun, and was carried on the top — in fact, formed the roof — of an outbuilding from which filthy gases emanate to be absorbed by the water, and thus that which should be the source of cleanliness and health was fouled and poisoned as a preparation for its use. That water can be rendered the earrier of disease by the absorption of foul gases, I presume few present will

doubt ; but I may refer you to a recent statement in the Times, where it was shown that typhoid fever had been com- municated to a number of cottages by the vapor from a drain in which the slop- water of the washing of the linen of the first patient suffering fivmthat fever had been thrown. By placing cisterns where they could receive foul gases, I have no doubt but that disease might be spread through a house ; but worse than this, the intermittent system is attended (when the supply is shut off, and the lower cis- terns are filling from the water remaining to the higher parts of the pipes) by an indrift into the general service main, and in this manner, as is well known, foul gases, in some cases even foul liquids, had been drawn into those mains ; and thus the disease is laid on from one house to another.

The constant service affords an agree- able contrast to this catalogue of loath- someness. The water being always at full pressure in the pipes, all that is re- quired is to turn the tap and draw the water cool, and as pure as it may be when supplied, unpolluted by foul gas or by foul liquid. But it is said by those among water- works, engineers and managers who still advocate the intermittent supply, that even assuming all these things to be true, the intermittent supply is a necessity, and that the waste of a commodity that is not paid for according to the quantity used, but is paid for in an annual rate, must be so excessive if the service is constant, that whatever may be the evils of inter- mittent supply, they must be submitted to, as the only means of preventing gross and unbearable waste. But the fallacy

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of these arguments has been exposed, and so successfully exposed, by the advocates of the constant supply, that the Legisla- ture has for many years past insisted on inserting in each Act for the supply of water to provincial towns a clause to secure consi ant supply ; but this legisla- tive care is operative in provincial towns only, and there is one most important ex- ception to this otherwise now genera! rule, and that exception, unhappily, is in the case of the metropolis.

In London, with its three and a half to four million inhabitants, the water supply is given over to eight companies, who reign supreme; the metropolis is divided into districts, each company has its own, and there is no competition, no new com- pany is permitted, and London is power- less. Various checks have been suggest- ed, and some have even come into opera- tion ; but the result is that, practically, the companies do as they please. Many years ago an Act was passed to give a constant supply to London, but the sec- tion will see that it is a perfectly dead letter when I tell the members that before a company can be compelled to afford a constant supply it must be demanded by a large majority of the inhabitants who are served by a " district main." It turned out that the term " district main" had no recognized meaning, and that it was im- possible to tell what group of houses would satisfy this term ; the result was, the Act was never put in force. About three years ago an Act was passed to cure the blunder in the former Act, and to ob- tain a constant supply for the metropolis. One of the provisions of that Act is that within six months the water companies should frame a set of regulations for the "fittings," and that those regulations should be submitted to the Metropolitan Board of Works, who, if they disapproved them, were to be heard before the Board of Trade. The eight companies drew up their regulations. The Metropolitan Board of Works did me the honor of re- ferring these regulations to me for exam- ination and for a report, and, as I consid- ered them most oppressive, I advised they should be opposed. I trust the section will bear with me when I mention one or two of the clauses of the regulations. The use of cisterns must be continued; nevertheless, all the pipes in the house must be replaced with pipes of a great

strength, unless, indeed, they happened to be of the excessive thickness demanded, which, however, was most unlikely. If there were a bath in the house, it must only have one opening for inlet and out- let, so that the clean water must come in through the dirty outlet. Moreover, it must not have a waste-pipe, because the water might be left on accidentally, and, if so, the owner would be punished by the bath overflowing and spoiling his ceilings and walls, and, perhaps, a few pictures. Cisterns were not to have any overflows except of a particular kind — that is, they were to be brought through the house wall into a place where the officer of the company could see them. When it was objected that this would in many cases involve great length of pipe and serious cutting away of plasters in order to carry the pipe down within the house to about the pavement level before bringing it through the wall, it was said, " Oh, bring it out through the nearest wall at what- ever floor the cistern may be" ; and the representatives of the company did not see any particular objection in the fact that any householder who did this would be liable to an action for damages for sud- denly giving a shower-bath to a passer- by, and they seemed to think the sugges- tion that ladies would not like to have good dresses or bonnets thus spoilt an idle one. The commissioners before whom the regulations were discussed, very greatly modified them in favor of the public, but nevertheless the Act is still practically inoperative, and probably will be till another outbreak of disease causes fresh alarm.

During the discussion on the question of constant supply to London, the advo- cates for it instanced Norwich, where, under efficient supervision, the consump- tion per head fell from between 25 and 30 gallons per diem on the intermittent sys- tem, to 15 gallons on the constant; Man- chester, a large city, where the result has been nearly as markedly favorable in re- lation to the constant supply ; and Shef- field, a town where it has been most suc- cessful, the supervision there having brought down the consumption to many gallons per head less with the constant than with the intermittent supply. On. the other hand, the supporters of inter- mittent supply in the metropolis have said : " Look at Liverpool ; here is the

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case of a town which began on the con- stant supply, and had to give it up, the waste was so great." No doubt this was so, and it was always felt to be a powerful argument in favor of the London advo- cates of an intermittent supply. They said, in effect, the requisite supervision becomes unfavorable in large towns (al- though Manchester was a success), and thus Liverpool was made a standing re- proach to the constant supply system. Liverpool was on the intermittent service when Mr. Deacon was selected to be the engineer to the Water Committee. Hap- pily for Liverpool and happily for the question of constant service, Mr. Deacon was not content to fold his hands and put up with things as he found them without an attempt to better them. He saw the expense and difficulty attendant upon a house-to-house inspection of the state of the fittings ; he knew how offensive such inspections are to those who are behaving properly and honestly ; and he set himself to devise an instrument by which he should be able to form a very good idea in which houses waste was going on, and to inspect those houses, and those only. His reflections on the subject had resulted in the water-waste meter which was now before them. This had been successfully in operation in several of the