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University of Wisconsin-Madison 
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A TEXT-BOOK. 

ON 

GAS, OIL, AND AIR ENGINES. 



Standard Engineering Works. 

GRIFFIN'S ''MOTOR" SERIES. 

NEW BOOK by Mr. CROMPTON. 

ELECTRICAL MOTORS. By R. K C&omfton, M.Iiist.E.E., M.IiiBt.C.E., 
^. With numerous Illustrations. [Shortly. 

HYDRAULIC POWER AND HYDRAULIC MACHINERY. By Henby 

BOBINSON, M.InBt.C.£., F.O.B., Prof, of Civil Engineering, King's College. Idurge 8to, 
Handsome Cloth, 31s. Second Edition. With 89 Plate$. 

NoU.— The SscoiTD Edition has been thoroughly Revised and Enlarged, and the number of 
Plates increased from 43 In the First to eo in the present Edition. 

STEAM AND STEAM ENGINES. Bv Prof. A. Jamieson, Glasgow and 
West of Scotland Technical College. With over 200 IllustratioDs and Six Folding 
Plates. Eighth Edition, Sb. 6d. 
"The BEST BOOK yet published for the use of Students."— jniflrifi«er. 

MARINE ENGINEERING (A Manual of). CompriBing the Designing, 

Construction, and Working of Marine Machinery. By A. £. Beaton, M.Inat.C.E., 
M.In8t.M.E., M.In8t.N.A.. &c. Eletbnth Edition. Demy 8vo, Cloth. With 
numerous Illustrations, reduced from Working Drawings, lOs. 
"Mr. Sbatom's Manual has ko bival"— TAe Times. 



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MARINE ENGINEERING RULES AND TABLES (A Pocket-Book 

oO- Por the use of Marine Engineers, Naval Architects, Designers, Draughtsmen, 
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M.Inst.Mech.B. With Illustrations. Pocket Size, Leather. 

SECOND Edition. Pocket Size, Leather, alto /or Office Use, Cloth, Ite. 

BOILERS, MARINE AND LAND: Their Construetion and 

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lings, and Pressures up to 200 lbs. per square inch. Safety Valves, Springs, Fittings 
and Mountings, Ac. By T. W. Traill, M:.In8t.C.E., F.B.B.N., Engineer Surveyor-in- 
Chief to the Boieuti of Trade. 
"Those who have tu design boilers will find that ther can settle the dimensions for any fflven 

pressure with almost no calculation by its aid. ... A most usbvul volvhb . . . supplying 

information to be had nowhere else."— TAe Engineer. 

MUNRO AND JAMIESON'S ELECTRICAL POCKET-BOOK. Elec- 
trical Bules and Tables for the use of Electricians and Engineers. By John 
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*' Wokdbbvdllt Pbbf bct."— JSZeetrieian. 

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the application of electricity is being considered."- >lreAttee(. 



INDISPENSABLE FOR THE ENGINEER. 

BY W. J. MACQUOBN BANKINE, C.B., LL.D., F.B.S., 
Late Reg. Prof, of Civil Engineering hi the U niversity of Olasgow. In Crown 8vo, Clotli. 
I.-A MANUAL OF APPLIED MECHANICS. Thirteenth Edition. 12s. Cd. 
IL-A MANUAL OF CIVIL BNGINEBRINO. Eighteenth Edition. Ms. 
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IV.— A MANUAL OF MACHINERY AND MILLWORK. Thirteenth Edition. 12s. ed. 
V.-USEFUL RULES FOR ENGINBEBS. ARCHITECTS, BUILDERS, ELB0TRIGIAN8, 

Ac. Seventh Edition, los. 6d. 
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Professor Tait, M.A., and Fine Portrait on Steel. Royal 8vo, Handsome Cloth. 81s. 6d. 



LONDON: CHARLES GRIFFIN & CO., LIMITED, EXETER STREET, STRAND. 



A TEXT-BOOK 



GAS, OIL, AND AIR ENGINES; 



OB, 



INTERNAL COMBUSTION MOTORS 
WITHOUT BOILER. 



BY 



BRYAN DONKIN, JUN? 

XBMBBR OF THB DISnTUTION 07 dYlL HHQTSWOtS. 



With 136 Illustrations. 



LONDON: 

OHARLES GRIFFIN AND COMPANY, LIMITED; 

EXBTER 'STREET, STRAND, 

1894. 

[All Rights Reserved.] 



•3 Ja'y5 

PEEFACE. 



Thb subject of Internal Combustion Motors, or engines for 
obtaining power without a boiler, is one of great and 
increasing importance, and it was, therefore, with pleasure 
that I undertook the following work at the request of the 
publishers. 

It is divided into three parts, treating respectively of 
Gas, Air, and Oil Engines. Part I., Gas Engines, is divided 
into two sections, the first dealing with the early history of 
these motors, and the second with modern gas engines. 
In this latter part particularly I am much indebted to 
numerous recognised authorities on the subject, especially 
to the excellent works of Professors Schottler and Witz, 
Mr. Dugald Clerk, Professors Jenkin and Robinson, M. 
Chauveau, and others. Information has also been obtained 
from the ProceedAnga of the Institution of Civil Engineers, 
Proceedings of the Institution of Mechanical Engineers^ 
Comptes Bendus de la SocietS des Ingenieurs CivUs, Zeit- 
schrift des Vereines deutscher Ingenieure, The Engineer, 
Engineering, and various other scientific and technical 
periodicals. A list is given of the literature of the subject, 
both English and foreign, which, it is hoped, will be found 
fairly complete. 

The Theory of the Gas Engine is briefly discussed in 



VI PRBFACtf. 

four chapters, and here I have had the advantage of the 
remarks and valuable criticism of Professor Capper, of 
King's College, London, who also kindly made for publi- 
cation in this work a new test upon the experimental Otto- 
Crossley gas engine in the engineering laboratory of King's 
College — a test which is, perhaps, as complete as any that 
have been published. Chapter XVII., on the "Chemical 
Composition of Gas " — an important part of the subject — 
has been entrusted to Mr. G. H. Huntly, A.B.C.S. of the 
State Medicine Laboratory, King's College, who is respon- 
sible for this chapter only. 

Care has been taken to consult the best authorities in 
England and on the Continent who have written on the 
theory and practice of gas engines, and to bring the matter 
up to date. I have much pleasure in acknowledging my 
special obligations under this head to M. Delamare- 
Deboutteville of Rouen, and Professor Schroter of Munich, 
for their kind assistance. To Professor Kennedy, F.RS., 
also, who has made many exhaustive and reliable tests on 
English gas engines, my acknowledgments are due. Not 
much original work appears to have been done in the 
United States, but the subject has been thoroughly studied 
in France and Germany. 

An Appendix is added, in five Sections, containing in- 
formation which it was not found possible to incorporate in 
the text One of them gives an abstract of the valuable 
experiments recently made by Dr. Slaby of Berlin, and 
published after the main portion of this work was 
complete. 

In conclusion, there only remains for me to emphasize 
the fact of the constantly increasing use of these motors 
in all countries for industrial purposes. Undoubtedly, 



PREFACE. . Vll 

there is a great future before them. There still exists, 
however, a large field for economy. In both Oil and Gas 
Engines, about 40 per cent, of all the heat received now 
goes off in the exhaust gases^ and about 35 per cent, in the 
jacket water. The better the economic results obtained, 
the greater will be the demand for these convenient motors. 
At present their chief recommendation is the absence of a 
boiler, which is of great advantage, especially for small 
powers. Even with the very high temperatures in the 
cylinders there is also little or no difficulty with lubrication. 
They are yearly increasing in size and power,* and will 
certainly before long, as more knowledge and experience 
are brought to bear on their construction, enter into for- 
midable competition with the best steam engines. They 
may even constitute the principal heat motors of the 
future. 

A list has been added of the chief tests on Gas, Oil, and 
Air Engines that have been published up to date. 

BRYAN DONKIN, J? 

London, November, 189S. 

* On going to press a notice of a Three-Cylinder Horizontal Double- 
acting Compound Gas Engine, indicating 600 to 700 H.P., is given in 
The Engineer of November 10, 1893. 



TABLE OF CONTENTS. 



FABT I.— GAS ENGINES. 



Chaptib L- 



-GbNEBAL DeSOBIPTION 07 THE 

OF ▲ Gas Engine. 



Action akd Parts 



Principles of heat motors, 
Comparison between a gas and 

a steam engine, . 
Advantages of a gas engine, 

Compactness, 

Ease in startins, . 
Disadvantages — Waste of heat. 
Study of a gas engine, 

I. Source of power, 

IL Utilisation of the explo 
sive force of the gas, . 
Workinff parts of an engine, 

Bed plate or base, 



Cylinders, pistons, aud valves, 
Cycle of operations, . 

I. Admission of gas and air 
to the cylinder, . 

II. Ignition of the charge, 

III. Explosion, and IV. Ex 
pansion, . 

V. Discharge of the gases, 

VI. Compression of the charge, 

Advantages of com- 
pression, . 
Lubrication and starting, 
Regulation of the speed, . 



6 

7 

7 
8 

9 

9 

10 

II 
II 
12 



Ghafteb II.~Heat Ctcles, and Classification of Gas Engines. 



Theoretical cycle, . 

Types of gas engines, 
L Non-compressing, . 
(a) Single or double-acting, 
(6) Atmospheric type, 



13 
14 
15 
15 
15 



II. Compression, ... 15 

(a) In a single cylinder, . 15 
(6) In a motor cylinder and 

pump, .... 16 



Chapter III.— History of the Gas Engine. 



Early combustion engines, 
HautefeuiUe, 
Hu^ghens, 
Papin . 
Barber, 
Street, . 
Lebon, . 



17 
18 
18 
18 
18 
19 
20 



Brown, 20 

Wright, .... 21 

Barnett, .... 21 

Drake, 24 

Distillation of sas from coal, . 24 
Barsanti and Matteucci's atmo- 
spheric engine, ... 25 



CONTENTS. 



Ohaptsr IV.—Histort of the Gas Engine — {Oontinued). 



Application of theory to prac- 
tice 29 

Lenoir, 20 

The original, horizontal, donble- 

aoting Lenoir engine, 31 

Description 31 

Working action of the engine, 33 

Trials— indicator diagram, . 35 

Hugon's vertical engine, . . 36 



Construction— Action, . 

Trials— Indicator diagram, 
Siemens' study of sas engines, 
Opinions of Schmidt, 
Million's jpatent. 
Beau de Rochas, 

His conditions for maximum 
efficiency, . 

His proposed four-cycle. 



36 
38 
39 
39 
40 
40 

40 
41 



Chaptkr v.— History or the Gas Engine — {CofUhvued). 



Otto and Langen vertical atmo- 
spheric engine, ... 43 
First type— 2 pistons, . . 44 
Second type— 1 piston,. . 45 
Construction of the engine, 45 
Working of clutch gear and 

other parts, ... 46 

Trials — indicator diagram, 48 

Gillee 49 



Hallewell, 

Brayton gas engine, . 

Simon vertical gas engine 

Construction, 

Tests and Indicator diagram, 
Ravel, .... 

Rotatory engine, . 

Oscillating engine, 
Foulis, .... 



50 
51 
51 
52 
53 
54 
54 
54 
55 



Chapter VI.— History or the Gas Engine- ((7ofi/inii«<i). 



Clerk horizontal engine, . 

Ignition and valves, 

<&vemor« .... 

Trials and indicatordiagrams, 
The Beck six-cycle engine. 

Trials and indicator diagram, 
Wittig and Hees, . 

Method of ignition, 

Seraine, 

Sturgeon, 

Martini, 

Tangye, 



56 


Victoria, .... 


. 69 


59 


SmaU gas motors, . 


. 69 


60 


Economic, 


. 70 


60 


Bonier and Lamart, 


70 


61 


Forest, .... 


. 71 


63 


Ewins and Newman, . 


71 


64 


Francois 


71 


65 


Warchalowski, 


72 


66 


Noel, .... 


72 


66 


Durand, 


72 


67 


Mire 


. 78 


68 


Baldwin,. 


73 



Chapter VII.— The Otto Gas Engine, 1876. 



Compression, the novel feature 

of the Otto engine, . 74 

The original German Otto 

engine, .... 75 

Description, ... 76 

Slide-valve, .... 79 

Movements of crank, counter 

shaft, and slide valve, . 82 



Regulation of the speed — 

Lubrication, ... 84 

Stratification of the charge, . 85 

Ignition by hot tube, . 86 

V arious types and designs, . 87 

Trials — Indicator diagrams, . 92 

Results of Society of Arts' trials, 93 

The Lanchester self-starter, . 94 



CONTENTS. 



XI 



Chaftbr VIU.— The Aticinbon Enginb. 



PAGB 

96 



Principle of the engine, . 
Differential engine, . . . »» 
Link movement and position, 09 



PAOS 

"Cycle "engine, ... 100 
(jonstruction, . . . 103 
Trials — Indicator diagrama, 106 



Chaftbr IX. — ^The Griffin, Bisschop, and Stockport Engines. 

The Griffin six-cycle engine, . 108 | Workincr method, .115 

Types, Ill , Trials—Indicator diagram, . 116 

Trials— Indicator diagram, . 113 , Stockport engine, . . .117 

Bisschop engine, . .113 1 Working method, . .118 



Chapter X.— Other British Gas Engines. 



Gas engines for electric lighting, 120 

Tangye, 121 

Fawcett 123 

Piston valves, . . .125 

Acm6, 126 

Trials, 127 

Fielding, 128 

Forward, .... 129 

Midland, 130 

Express, 131 

Doagill, 131 



Trent, . 

Robson's Shipley, 

Trusty, . 

Premier, . 

National, . 

Palatine, . 

Robey, . 

Various small engines, 

Day engine, 

Campbell, 

Roots, 



132 
133 
133 
133 
133 
134 
134 
135 
135 
137 
137 



Chapter XI.— French Gas Engines. The Simplex. 



The Simplex engine— Cycle, . 138 
Electric ignition, . . . l;^9 
Slide-valve, .... 144 

Governor, a. Air barrel governor, 144 
&, Pendulum governor, 147 



Starting 148 

Trials— Indicator diagrams, . . 150 
Lencauchez Gas for driving 

Simplex engines, 151 



Chapter XII.— The Modern Lenoir and other French Engines. 



Modem Lenoir engine, . 

Construction, 

Trials — Indicator diagram, 

Charon 

Tenting, .... 
Ravel (new type), . 



161 
152 
155 
155 
157 
157 



Forest, 159 

Niel — Trials and indicator 

diagrams, .... 150 
Lalbin rotatory engine, . .161 
Various small French engines, 162 



Xll 



CONTENTS. 



CEAfTBR Xin.— ObRMAN GaS EKaiNXS^THX KOEBTINO-LlBOKSVLDT, 

Adam, and Bbnz. 



VJlQK 

The Koerting-Lieckfeldt engine, 163 
Original type, 1881, . . 164 



^^iginal type, 
Modem type, 1888, 
Governor, 
Horizontal type, . 
Trial 



165 
167 
168 
171 



Adam engine, . . . .171 
Vertical type, . . .171 
Four-cylinder vertical type, 173 
Trials, 175 

Benzenffine 175 

Working method and cycle, 177 
Trials, 178 



Chapter XIV.— Other German Engines. 



Daimler, 178 

Method of action, . .179 

DOrkopp, 181 

Dresdener Gas-motor, .182 

Kappel 183 

Lutzky, 183 

Berliner Maschinen-Bau Motor, 184 



Sombart, 184 

Slide valve with flame igni- 
tion, 185 

Capitaine vertical engine, . 185 

Theory 185 

Construction and working 

cycle, .... 187 



Chapter XV.— Gas Production for Motive Power. 



Production of gas from coal, . 189 
Gaseous fuels, . . .190 

I. Natural gas, . . .191 
XL Oil sas, . . 191 

III. Carburetted air, . . 191 
rV. Coal cas, . . . 191 

1. Distillation of coal, 191 

2. Combustion of coal, . 192 
Methods of producing gas from 

coal, 192 

a. Producer gas, . . .192 
6. Water gas, . . .192 
e. Poor gas (Dowson, Len- 

cauchez), . . . .193 
Gas producers, . .193 



Bischof, 

Thomas and Laurent, . 

Kirkham, 

Siemens, 

Pascal, .... 

Tessi^ du Motay, . 

Strong .... 

Lowe, .... 

Wilson, 

Lencauchez, . 

Dowson, 

Method of veneration. 
Cost of production, . 
Experiments with Dowson 



193 
193 
193 
194 
194 
194 
195 
196 
197 
197 
200 
200 
202 

204 



Chapter XVI.— The Theory of the Gas Engine. 



Laws of gases, .... 

I. Boyle's law, 

II. Gay-Lussac's law, . 
Laws of thermodynamics, 

I. Joule's law of the mechani- 
cal equivalent of heat, . 
Heat and energy, con- 
vertible terms. 
Thermal units, . 
Specific heat, . 
Table of specific heats of 
jeases, .... 
n. Carnot*B law, . 



20.5 1. Isothermal curve, . . 214 

206 2. Adiabetic curve, . . 215 

207 Camot's perfect theoretical 

209 c^de— Diagram, . .215 

Conditions of Ideal efficiency, . 217 

209 Other cycles, .... 218 

Stirling's cycle — Constant 

209 volume (diagram), . . 218 
211 Ericsson's cycle — Constant 

211 pressure (diagram), . . 218 
Method of taking indicator dia- 

213 grams 219 

213 Movements of heat, . . 220 



CONTENTS. 



XIU 



Chapter XVII.— The Chemical Composition of Gas in Gas Engines. 



Specific properties of gases, 

Atoms and moIeculeB, 

Avogadro'a law, 

Chemical symbols, . 

Atomic weights, 

Molecular weights, . 

Specific heats of gases, . 

Heat of combustion of gases, 

Gas calorimeters. 

Tables of B.T.U. evolved by 
combustion of 1 cubic foot 
of different hydrocarbons, . 



PACK 

221 Composition of coal gas, . 

221 I Quantity of oxygen required 

221 ! for combustion, . 

222 Table of products of combus- 

222 tion, 

223 Table of composition of lighting 

223 gas in different towns, 

224 Calorific value of 1 cubic foot 
224 ofgas, . . . . 

Composition of poor gases, 
Heating value of Siemens' pro- 
ducer gas, .... 



PAOB 

226 
227 



229 

230 
231 

231 



Chapter XVIIL— The Utilisation of Heat in a Gas Engine. 



Gas power compared with steam, 
Latent heat of steam, . 
Percentage of heat utilised 
in a gas engine, 
Him*s balance of heat, . 
Expansion — Various efficiencies, 
1. Maximum theoretical effi- 
ciency, .... 
n. Actual heat efficiency, . 
m. Ratio of the two, . 
IV. Mechanical efficiency, . 
Ideal diagram of a perfect cycle, 
Actnal indicator diagram of an 
Otto engine, 



232 
232 



234 



235 
235 
235 
235 



Efficiency formula for gas engine 
types 

1. Direct acting non-com- 
pression, .... 

2. Compressing — Explosion 
at constant volume, . . 

3. Compressing — Explosion 
at constant pressure, 

4. Atmospheric ^ engines, . 
Numerical calculation of actual 

efficiency in a gas engine, . 

Heat balance sheet of four gas 

engines, • • • • 



238 



239 

240 
240 

241 

242 



Chapter XIX. —Explosion and Combustion in a Gas Engine. 



Definition of terms — Ignition, 
explosion, inflammation, 
combustion, . . 243 

Velocity of flame propagation 

in gases, .... 243 
Bunsen's experiments, . . 243 
Mallard and Le Chatelier's 

exijeriments, . . . 244 
Berthelot and Vieille*s ex- 
periments, . . 246 
Witz's determination of influ- 
ence of speed, . . . 247 
Experiments, . 248 
Clerk 8 experiments on pres- 
sures of gaseous mixtures, 249 
Explosion in a closed vessel, 251 
Wall action in gas engine 

cylinders 252 



1. Time during which wall 
action lasts, . . 252 

2. Intensity of wall action, . 253 

3. Proportion between wall 
area and volume, . 263 

Losses of heat, . . . 253 

Variations in the expansion 

curve, attributed to . . 254 

a. Stratification, . . . 255 
Experiments on an Otto 

engine, .... 256 

b. Dissociation — Clerk, . 257 

c. Cooling action of walls — 
Witz, .... 258 

d. Increase of specific heats — 
Mallard and Le Chatelier, 259 

Cylinder wall action, . . 259 
Flow of heat through cylin- 
der walls, . • . 260 



CONTENTS. 



FABT II.— PBTEOLBUM ENGINES. 

Chaptbb I.— The Discovert, Uth^isation, and Pbopbbties of Oil. 



Derivation of the name "petro- 
leum," .... 

Discovery of petrolenm in 
different conntries, . 

a. Russia, .... 

b. America, .... 

c. Scotland (shale oil). 
Chemical composition of oil, . 
Distillation — Varying densities 

of oils, .... 

Flashing point — Method of 
determining it (AbePs 
test), .... 

Ignition point, 

&bles of properties and heating 
value of oils, 

Robinson's experiments on 

oil, 

Distillation at high tempera- 
tares, • • . . 



263 

263 
264 
264 
265 
265 

266 



267 
268 



269 
270 



Evaporation at low tempera- 
tures 270 

Pressures at varying tempera- 
tures, .... 270 
Utilisation of oil, ... 272 
I. Petroleum as fuel, . . 273 
Liquid fuel on Russian rail- 
ways 275 

Cost of working, . . 275 
Liquid fuel on an English 

railway, .... 276 

The Bailey — Friedrioh engine, 277 

n. Oil Gas, . . . .277 

Tables of composition and 

heatins value of oil gas, . 279 

Oil gas producers, . . 279 

Mansfield, .... 279 

Keith 281 

Rogers, .... 281 

Pintsch 282 



Chapter IL—Histobioal— Working Method in Oil Engines — 
Carbuketted Air. 



Oil motors, .... 
IIL Carburation of air at ordin- 
ary temperatures, . . 283 
a. Hot distillation, . . 284 
6. Cold distillation, . . 284 
Carbnrators, ... 285 
Lothammer, . . 285 
Meyer, .... 286 
Schrab, .... 286 
IV. Utilisation of petroleum 

in a cylinder, . . 287 



283 I Oil Engines, . 
Hock, . 
Brayton, 
Carburator 



288 
288 
289 



for heavy 

petroleum, . . . 290 

Trials — Indicator diagram, 292 

Spiel, 292 

Oil consumption — Indi- 
cator diagram, . 293 
Siemens' regenerative engine, 294 



Chapter III.— The Priestman Oil Engine and Yarrow 
Spirit Launch. 



Requisites of oil engines, . 297 
Description of the Priestman 

engine, .... 297 

Spray maker, . . 299 

Vaporiser, .... 300 

Qovemor, .... 301 



Electric ignition, . . .301 
Trials — Indicator diagrams, 303 
American type, . . . 305 
The Yarrow spirit launch, . 305 
Comparison of steam with 
petroleum spirit, 306 



CONTENTS. 



XV 



Chaptbb IV.— Other Oil Engines. 



PAOK 

308 



Classification, .... 

a. Motors with spray maker, 308 

6. Motors without spray 
maker, .... 308 
Homsby-Akroyd, . . .310 

Trial — ^Tndieator diagram, . 312 
Tmsty, 312 

Trial — Indicator diagram, . 314 
Roots* petroleum motor, . 314 

Otto oil engine, . 315 

Indicator diagram — ^Trial, . 316 
Griffin oil engine, . .316 

Weatherhogg, . .318 

Rocket, 318 

Lenoir 318 

Original type of carburator, . 318 



Modem type of carburator. 
Trials — Indicator diagram, 

Simplex— Carburator, 

S^urit4, .... 
Description of the engine, 

Ragot, .... 

Tentinff, .... 

Durano, .... 

Forest, .... 

Capitajne, 

Daimler, . . « . 

Adam, .... 

Altmann and Kttppermanu, 

Liide- Vulcan, . 

Various American engines, 



rA«a 
319 
319 
320 
321 
321 
323 
324 
325 
325 



jYote.— Oil industry in the Caspian region. 



328 
329 
330 
330 
331 



:m 



FABT III.— AIE ENGINES. 



Theory of hot air engines, 
Cii^ley — Bucketthot air engine, 

Working method, 

Trials— Indicator diagram, . 
Stirling, . 

Regenerator, 

First engine. 

Second engine, 
Robinson, 



337 ; Ericsson, .... 

.339 Wenham, 

339 Bailey, .... 

340 Trial — Indicator diagram, 

340 Rider, .... 

341 Jenkin's regenerative engine, 
341 Bonier 

343 Results of trials, . 

344 Diesel's new motor, . 



346 
346 
347 
348 
349 
351 
352 
353 
354 



APPENDIX. 

Section A. — Professor Capper's trial on an Otto-Crossley engine, . 355 

„ B. — Translation of Beau de Rochas' patent, .... 366 

„ C. — List of gas, oil, and air engine patents, .... 368 

,, D.— nSummary of experiments on an Otto engine. Dr. Slaby, . 389 

E.— Table of trials 400 

BlBUOOKAFHT, 408 

Index,. • . • • 411 



LIST OF ILLUSTRATIONS. 



1. Barnetf 8 Engine — Gas Ignition Cock— Longitudinal and Trans* 

verse Section, ..... 

2. Barsanti and Mattenccrs Gas Atmospherio Engine, 

3. Lenoir Horizontal Engine, 

4. Lenoir Engine— Section of Cylinder, 

5. ,, Indicator Diagram (Slade), 

6. Hugon Gas Engine — ^Vertical, 

7. „ Indicator Diagram (Clerk), 

8. Otto and Langen Vertical Engine— Transverse Section, 

9. ,, -Clutch Gear, . 
9a, „ Engine — Plan, . 

10. „ Engine— Indicator Diagram (Clerk), 

11. Simon Vertical Engine, .... 

12. Bray ton Gas Engine— Indicator Diagram (M'Mutrie), 

13. Simon Engine — Indicator Diagram (Slaby), 

14. Clerk Engine — Sectional Elevation, 

15. „ „ Plan, . 

16. „ Ignition Valve, 

17. Clerk 6 RP. Engine— Indicator Diagram (Clerk), 

18. ,, 12 iL.ir, ,, „ ,• 

19. Beck Engine — Indicator Diagram (Kennedy), 

20. Wittig and Hees Engine— Ignition Valve — Sectional Plan, 

21. Sturgeon Engine— S^tional Elevation, 

22. Otto Engine, 1876— Side Elevation, 



23. 
24. 
25. 
26. 
27. 
28. 
29. 
30. 

31. 
32. 



Sectional Plan, 
End View, 

Sectional Plan of Slide Valve, 
Vertical View of Slide Valve, 
„ Cover, 

Ignition Flame and Slide Valve, 
„ „ Cover, 

Positions of Crank, Counter Shaft, and Slide 

Valve, . . 

Positions of Ports and Passages, 
Exhaust Valve, 
Oiling Apparatus, 



26 
82 
33 
35 
37 
39 
44 
46 
47 
49 
52 
53 
53 
57 
58 
59 
61 
61 
63 
64 
67 
76 
77 
78 
79 
80 
80 
81 
81 

82 
82 
83 
84 



XVUl 



LIST OF ILLUSTRATIONS. 



no. PAOB 

34. Otto Engine, 1876— Ignition Valve (Tnbe), ... 86 

36. Otto-Cro68ley Two-Cylinder Horizontal Engine, ... 88 

36. „ Vertical Domestic Motor, .... 89 

37. „ High Speed Single-Cylinder Horizontal Motor, . 91 

38. Otto Engine— Indicator Diagram (Slaby), ... 92 

39. ,, „ (Brooks and Steward), . 92 

40. „ „ (Garrett), ... 93 

41. „ ,, (Society of Arts), . . 93 

42. Atkinson Differential Engine — Sectional Elevation, 98 

43. „ „ Piston and Links, positions, . 100 

44. Atkinson Cycle Engine — Elevation, .101 
46. „ Plan 102 

46. „ Link and Toggle Motion, , 104 
46a. „ Ten Positions of Crank, &c., . . 106 

47. „ Indicator Diagram (Unwin), . 106 

48. Atkinson Differential Engine— Indicator Diagram (SchSttier), . 106 



49. Atkinson Cyde Engin< 

60. „ „ (Tomlinson), 

61. „ 100 H.F. nominal, 

62. Griffin Six-Cycle Engine— Side Elevation, 

63. „ Plan, . 

64. Griffin Engine— Indicator Diagram (Kennedy), 
66. „ „ (Society of Arts), 

66. Bisschop Engine — Sectional Elevation, 

67. „ Section of Piston Valve, 

68. » Indicator Diagram (Clerk), 

69. Stockport Engine — Single Cylinder, 
69a. Tangye Engine— Twin-Cylinder, . 

60. Fawcett Engine— Sectional Elevation, 

61. „ Plan of Valve Piston, . 

62. Day Engine — Sectional Elevation, 

63. „ Indicator Diagram, 

64. Simplex Engine— Side Elevation, . 
66. „ End View, 

66. „ Sectional Plan, . 

67. t> »> of Admission Valves, &c., 

68. „ Pendulum Governor, . 

69. „ „ . . 

70. „ Starting Gear, . 

71. „ Positions of Piston, 

72. „ Indicator Diagram (Witz), 

73. „ „ of 8 H.P. Engine, 

74. Modem Lenoir Engine— Sectional Plan, . 
76. „ „ Indicator Diagram (Tresca), 
76. Kiel Engine— Sectional Plan, 
77* ft Indicator Diagram (Moreau), • 



(Society of Arts), 106 
106 
107 
110 
110 
112 
113 
116 
116 
116 
117 
122 
124 
126 
136 
136 
141 
142 
143 
146 
147 
147 
148 
148 
160 
160 
163 
166 
160 
161 



LIST OP ILLUSTRATIONS. 



XIX 



no. 
78. 
79. 
80. 
81. 
82. 



Lalbin Engine— SectiooAl Elevation, 
Koerting Engine — Sectional Elevation, . 
„ Ignition Valve, 

, , Governor— Elevation, . 

Koerting Horizontal Engine — Elevation, . 
82a. Koerting Engine— End View, Valves, &c., 

83. Adam Engine — Sectional Elevation, 

84. Adam Twin-Cylinder Engine — Side Elevation, 



85. 
86. 

87. 
88. 



Plan, 
Section, 



Benz Engine — Elevation, .... 

Plan 

Daimler Engine — Section, .... 

„ Elevation, 

Sombart Engine — Ignition Valve — Vertical Section, 
„ „ Plan,. 

93. Capitaine Engine— Sectional Elevation, . 

94. Strong Gas Producer, .... 
Lencauchez Gas Producer — Sectional Elevation,. 
Dowson Gas Plant, .... 

„ at Mead's Flour Mills, Chelsea, 

Diagram of Camot's Perfect Cycle, 
„ Stirling's Cycle, 

„ Ericsson's Cycle, 

„ Perfect Cycle with Compression, 

102. Otto Engine — Actual Indicator Diagram, 

103. Witz— Time Diagram, .... 

104. Mansfield Oil Gas Producer, 
Brayton Carburator, .... 
Brayton Petroleum Engine — Indicator Diagram, 
Spiel Engine — Indicator Diagram, 
Siemens' Regenerative Engine, . 
Priestman Oil Engine — External Elevation, 

,, „ Section of Cylinder and Valves, 

„ „ Spray maker, 

„ „ Vaporiser, 

,, ,, Indicator Diagram, 

114. Homsby-Akroyd Engine— Sectional Elevation, . 

115. „ ,, Indicator Diagram, . 

116. Trusty Oil Engine— End View, . 

117. ,) M Indicator Diagram, . 

118. „ ,, External view, 

110. Otto Petroleum Engine — Indicator Diagram, 

120. Lenoir Petroleum Engine— External View, 

121. „ „ Indicator Diagram, . 

122. Simplex Carburator, .... 



90. 
91. 
92. 



95. 

96. 

97. 

98. 

99. 
100. 
101. 



105. 
106. 
107. 
108. 
109. 
110. 
111. 
112. 
113. 



PAaa 
162 
166 
167 
168 
169 
170 
172 
174 
176 
175 
176 
176 
180 
180 
185 
185 
188 
195 
198 
201 
203 
215 
218 
218 
236 
237 
249 
280 
291 
292 
293 
295 
298 
299 
300 
300 
303 
309 
312 
313 
314 
314 
316 
319 
319 
320 



LIST OF ILLUSTRATIONS. 



123. Motetir S^curit6— External View, 

124. BAgot Engine— External View, . 

125. Daimler Oil Engine— Section of Cylinder and Valves, 

126. Buckett Hot Air Engine, .... 

127. „ 19 Indicator Diagram, 

128. First Stirling Engine, .... 

129. Second Stirling Engine, 1840, 

130. Bailey Hot Air Engine, .... 

131. ,, „ Indicator Diagram, 

132. Rider Hot Air Engine, .... 

133. Bonier Hot Air Engine, .... 

134. Capper's Trial— Pumping Stroke, 

135. „ Mean Indicator Diagram. 

136. „ Time Diagram, . 



323 
329 
339 
340 
342 
343 
347 
348 
350 
352 
355 
356 



A TEXT-BOOK OF 
GAS, OIL, AND AIE ENGINES. 

PART I.— GAS ENGINES. 



CHAPTER I. 

GENERAL DESCRIPTION OF THE ACTION AND PARTS 
OF A GAS ENGINE. 

CoiTTiNTS. — ^Introduction— Advantages of a Gas Engme— Waste of Heat — 
Source of Power — Utilisation of Motive Force— rarts of a Gas Engine 
— Transmission — Admission of Gas and Air — Ignition — Explosion and 
Expansion — Exhaust— Compression — Oiling— Regulation of Speed. 

The principles goyeming the construction and action of a gas 
motor are almost the same as those of a steam engine. In both 
the object is to obtain useful work from heat. This is effected 
by raising gas or water to a certain temperature, producing in 
the one case steam, in the other flame, and with the pressures 
resulting from the increase of heat in the steam or flame driving 
forward a piston connected to a shaft. The science of thermo- 
dynamics proves that there exists a strict ratio between the heat 
evolved and the work performed. The laws governing the pro- 
duction of this heat energy are always the same, whatever the 
medium or agent of motive force. 

In all mechanical motors there are three factors to be con- 
sidered : — 1st. The caui^e of motion, varying according to the 
type of motor. In heat engines it is caloric obtained in various 
ways, as from combustion of coal in a boiler or hot air furnace, 
or by the explosion of inflammable gases. 2nd. The effect pro- 
duced, or the energy into which the heat is transformed ; this 
usually takes the form of pressure upon a piston working on to 
a crank. So far, all heat motors are alike. 3rd. The particular 
mechanism, differing in each kind of motor, by which this trans- 
lation of heat into work is utilised. The difference between 
steam and other kinds of motors, such as gas, hot air, petroleum. 



2 0A8 ENGINES. 

Ac, lies in the means employed to generate the heat, and turn it 
into work. 

A steam motor consists of three indispensable parts, the fur- 
nace, the boiler, and the cylinder containing the motor piston. 
These may be in close proximity to each other, but there is 
usually a separate building for the boiler, <fec. The process of 
starting a steam engine is relatively slow and laborious. The 
fire must be kindled and combustion obtained in the furnace, 
and the water in the boiler brought to boiling point and evapor- 
ated into steam. The temperature must then be raised until 
the pressure of the steam, produced by the increase of tempera- 
ture, is sufficient to propel the motor piston. 

Advantages of a Gkts Engine. — In a gas engine these 
operations are much simpler, because it is so constructed that, 
for the work it has to perform, it is complete in itself, containing 
on one foundation the equivalent of furnace, boiler, and cylinder. 
It is in the cylinder that the production and utilisation of the 
heat takes place, and the entire cycle, or series of operations, is 
completely carried out. Highly inflammable gases and air are 
first admitted into the cylinder. They are, at a given moment, 
exploded by the application of heat or flame ; the pressure and 
the temperature are at once considerably raised, and the piston 
is driven forward. In a steam engine the working agent is pro- 
duced separately and continuously, but in a gas motor the 
inflamed gases, which act as the medium of heat, must be gene- 
• rated afresh at each stroke of the piston. With gas there is very 
little difficulty in obtaining an explosion, and a corresponding 
backward and forward stroke, as many times in a minute as is 
required. As combustion takes place in the cylinder itself, 
pressures and temperatures much greater than those developed 
in steam engines are easily and quickly produced. Hence gas 
motors are called *' internal combustion " engines, and the same 
name is used for all motors in which the heat is generated 
inside, instead of outside, the cylinder. 

This brief outline of the working of a gas motor shows the 
advantages it possesses in practice over the steam engine— 
namely, compactness and £Eu:ility in starting. Theoretically, it 
is also superior, because higher temperatures and higher pres- 
sures are available, to act upon the piston. But in all heat 
motors hitherto made, there are defects which the skill of the 
best constructors has not yet been able to overcome — namely, 
waste of the greater part of the heat generated, and consequent 
loss of pressure, or of useful work done upon the piston. 

Oonsidering, first, the practical advantages of the gas engine, 
as far as compactness is concerned, it leaves little to be demred. 
The space it occupies is small, a few square feet being sufficient, 
instead of the separate boiler and chimney necessary with a 
steam engine. A gas motor can be fixed almost anywhere, bat 



OENEBAL DESCRIPTIOK. 3 

it should stand on a solid foundation, to counteract the vibra- 
tions caused by the repeated explosions. To place it in proper 
working condition, all that is required is a gas supply pipe, and 
a water tank with pipes for cooling the cylinder. The high 
temperatures produced by the explosion of the gases necessitate 
the use of a jacket round the cylinder, through which water 
circulating automatically from a tank passes continuously, to 
keep it cool ; this jacket water is used over and over again. 
These pipes, with a third communicating with the outer air, 
and providing an outlet for the burnt gases, constitute all the 
necessary working connections. 

A gas engine thus easily fixed, can also be set in motion and 
started in a few minutes. If a gas jet or hot ignition tube is 
used to fire the charge, it is of course previously lighted ; where 
combustion is obtained electrically, the generation of the sparks 
is produced before the engine is started. A few turns by hand 
or other means are given to the flywheel, while the exhaust is 
kept open, and the engine is then fairly at work. To stop it, 
nothing is needed but to turn off the supply of gas. For small 
manufactures the convenience of having a motive power at hand, 
easy to start or stop in a few moments, is so great, that smaU 
gas motors are rapidly superseding, not only steam, but manual 
labour. It cannot be denied that they are rather more costly 
than steam, but of late years their consumption of gas per H.P. 
has been much reduced. In proportion as the quantity of 
gas required to drive them is diminished, and the economy 
obtained is greater, the more popular and cheaper will they 
become. Practically, there is less danger of fire than with steam 
boilers, and thousands of gas engines are now used in places 
where steam could never be employed. 

It is in the smaller gas engines that these practical advan- 
tages are chiefly felt, but the theoretical superiority of these 
motors, obtained by the high temperatures at which they can be 
worked, apply equally to engines of all sizes. But as soon as 
large powers are required, and the gas engine enters into active 
competition with steam, it becomes of far greater importance to 
economise the consumption of gas. The temperatures and pres- 
sures obtained by the inflammation and explosion of gas in a 
cylinder are so high, that engineers have not yet succeeded in . 
utilising them to their full extent. Hence, there is much waste 
of heat and consequent loss of pressure, and these defects in the 
working of a gas engine afiect injuriously the expenditure of 
gas. If heat be wasted, more must be supplied, and more gas 
must be used to produce it. 

Waste of Heat. — In a steam engine the main object should 
be to keep the cylinder walls as hot as possible, to prevent 
the condensation of the steam. The difficulty of generating 
steam, and maintaining its temperature and pressure, is in- 



4 GAS ENGINES. 

creased, because there is a change of physical state from a liquid 
to steam. With a gas engine the reverse process is necessary, 
and the cylinder walls must be cooled. The gas is dry, and the 
heat developed by the explosions taking place in the cylinder 
acts directly on the piston. A considerable amount of steam is 
condensed in the pipes of a steam engine, whereas in a gas motor 
there is no similar waste, because all the heat is generated in the 
cylinder itself. Nevertheless heat is lost, but in a different way. 
The temperature of the gas at the moment of explosion is relatively 
high. It is generally assumed to be about 2,730" F. (1,600' C), 
but this is known not to be the highest temperature reached. 
Whatever the actual temperature, the heat is always too great to 
be retained ; a large portion is sacrificed, to prevent injury and 
destruction to the parts, and heat is also carried off continuously 
by the cooling water round the cylinder. In the early double- 
acting engines, not more than 4 per cent, to 6 per cent, of the 
total heat received was employed in doing work, and more than 
half was wasted, that the walls might be 'kept cool. If to this 
be added the heat escaping from the cylinder in the exhaust 
gases, or the products of combustion, it is not difficult to under- 
stand how, formerly, from 94 per cent, to 96 per cent, of the heat 
was dissipated. 

It is this waste of heat in a gas motor that causes the loss 
of pressure, or diminution in the work done on the piston. 
With all gases the pressure increases with the rise in tempera- 
ture, and, therefore, the higher the temperature, the greater will 
be the pressure produced, or the expansion of the gases. If this 
pressure be expended in doing work, and acting on the piston, 
the whole may, if expansion be continued long enough, be utilised 
in useful work. But to obtain this result with the pressures 
generated in a gas engine, the cylinder and piston must be of 
great length, and the piston allowed to move out as long as 
there is any expansive force left in the gas to act upon it. As 
this is practically impossible, the other plan is to diminish the 
quantity of gas admitted into the cylinder. Before compres- 
sion was employed, it was difficult to proportion the supply 
of gas to the expansion, and it is a delicate process even in a 
modem engine, in which the gases are compressed before ex- 
plosion. 

When the theory of the gas engine began to be really under- 
stood, the principal problem was, how to obtain sufficient 
expansion from the exploded gases. The test of efficiency 
in any heat engine is the proportion between the total heat 
supplied, and the total useful work obtained. As far as work is 
concerned, all the heat which is not employed in producing it is 
wasted. Thus to be really efficient, a gas engine ought to furnish 
a maximum amount of useful work with a minimum consumption 
of gas. This is only possible if the expansion of the gases is 



GENERAL DESCRIPTION. 

rapid and prolonged. The greater the time allowed them to act 
upon the piston, and the farther they drive it, the more heat 
energy will be expended in work, and the less will be discharged 
as waste into the atmosphere. Expansion should also be rapid, 
because the more quickly the piston uncovers successive portions 
of the cylinder walls, the less time will there be for useful heat 
to be carried off from the hot gases to the cooler walls. This 
important question of expansion will be more fully examined, 
when considering the theory and utilisation of heat in a gas 
engine. 

The study of a gas engine falls naturally into two divisions : — 

I. The source of power, or motive force. 
II. Its mechanical utilisation. 

I. Source of Power. — In all heat engines the source of 
power is heat, and gas is the medium or agent through which it 
acts in a gas motor. The gas is ignited, and the explosive force 
thus generated is used to drive forward a piston. Many different 
kinds of gas, varying in heating value, are employed, and the 
effects obtained by ignition and explosion cannot be determined 
without a knowledge of the chemical constituents of the gas, 
and the proportions in which they combine with air. Since the 
gas used in an engine cylinder does not contain the oxygen 
necessary for combustion, it can never be burnt by itself, but 
must always be diluted with a certain quantity of air. Unless 
the composition of the gas and the ratio of its dilution with air 
are known, it is impossible to ascertain the temperatures and 
^pressures attained in the cylinder, and to calculate the theo- 
retical work, or the work it ought to do. The study of gases 
has led to the discovery of the law of dissociation, or the property 
they possess, after they have attained a certain high temperature, 
of resolving into their separate elements. The phenomena of 
ignition in a cylinder also prove that the whole heat of the gases 
is never developed at once, whatever the gas used, or the pro- 
portions in which it is diluted with air. It appears probable 
that combustion is seldom complete and instantaneous, but con- 
tinues during the forward motion of the piston, after the first 
propagation of heat which causes the explosion. These and 
other questions connected with the phenomena of combustion 
in a gas engine are only mentioned here, and will be discussed 
later. 

II. Utilisation of the Explosive Force, &;c. — In the 
second part of the subject we have to consider the mechanical 
utilisation of the motive force, or the method by which it is 
turned into rotatory motion. This includes a study of the con- 
struction and parts of a gas engine, as the apparatus used for 
the transformation of heat into useful power. There is this 
peculiarity in its structure, that the cylinder contains in itself 



6 OAS ENGINES. 

furnace and boiler, and in it the motive power is developed* 
Before examining in detail the various types, it will be well to 
explain the principal parts of a gas motor, and its internal 
organisation. We will first enumerate these parts, and then 
describe the functions they have to perform, as also the different 
operations taking place in a gas engine. 

Base. — ^The base plate on which the engine is fixed is of cast 
iron, and usually very solid. In some engines it forms a hollow 
casing on which the cylinder is bolted, and the air for diluting 
the gas is often drawn through it. In many of the modem 
horizontal motors using compression, the hollow base acts as a 
reservoir, and the mixture of gas and air is compressed into it, 
before passing through to the motor cylinder. 

Cylinder. — The cylinder, solidly bolted to the base, is either 
vertical or horizontal, according to the type of motor. Few gas 
engines have more than one motor cylinder, working single 
acting; it is almost always open to the atmosphere at the crank 
end, and closed only by the piston. Except for large sizes a 
second cylinder is seldom needed to increase the motive power, 
sufficient force being obtained by the succession of explosions in 
one cylinder. With higher powers two or more single-acting 
cylinders are usually employed. As the great object in a gas 
engine is to allow the gases to expand' as completely as possible, 
it seems at first as though this end would be best attained by 
making the engines compound, like steam engines, and causing 
the gases to expand successively in different cylinders. Though 
often tried, this arrangement has rarely been found successi^ 
Sometimes an auxiliary pump is used for compressing the mix* 
ture, or a charging cylinder for receiving and mixing the gas 
and air. Occasionally compression is obtained in the motor 
cylinder itself, and the motor piston acts on one side as a pump. 
A special feature of gas engine cylinders is that, on account of 
the great heat developed, they are always provided with some 
apparatus for cooling the walls. In the smallest types it has 
been found sufficient to make the outer radiating surfaces of the 
cylinder ribbed or deeply indented, exposing a large cooling area 
to the air. In engines developing above two or three horse- 
power, a jacket with water constantly circulating through it is 
indispensable. As one end of the cylinder is almost always 
open to the air, the cylinder metal is kept cool, and over- 
heating is prevented by contact with the outer air, but chiefly 
by the water jacket. 

Pistons. — The pistons of gas motors are very similar to those 
of steam engines, but longer. One or two types have valves in 
the pistons, to admit air or discharge the exhaust gases. Plunger 
pistons are generally used. 

Valves. — ^The valves of a gas engine have more important 
functions to perform than the admission and exhaust valves of 



GENERAL DESCRIPTION. 7 

a steam engine. Not only do they admit the gases into the 
cylinder and discharge the products of combustion, but they are 
f^quently used to assist in mixing and firing the gas and air. 
In the older types of engine, as in the early Otto, there is 
generally one slide valve for admitting, mixing, and igniting the 
charge. It contains ports to receive and pass on the gas and air 
to the cylinder, and carries a lighted flame within a cavity to 
kindle the charge, after it is mixed and compressed. In most 
modem engines lift valves alone are used, but occasionally the 
mixture is admitted to the cylinder through cylindrical or piston 
valves, or a revolving disc. In most engines the valves are 
worked by cams on a side shaft driven from the main shaft, or 
by eccentrics ; in others they are automatically lifted or closed 
by the pressures in the cylinder. 

TransinisBion. — As in a steam engine, the power is generally 
transmitted direct from the piston-rod and connecting-rod to the 
crank shaft, but sometimes through intermediate parts. Occa- 
sionally there is no connecting-rod, the piston working direct on 
to the shaft To obtain greater regularity in the action of the 
engine, the flywheel is usually made larger and heavier than in 
steam engines. Most gas engines have only one explosion per 
two revolutions, and the energy of the flywheel is required to 
carry the piston forward, take in a fresh charge of gas and air, 
and to bring it back to the dead point after explosion. 

In all gas engines five operations are required for a com- 
plete cycle — I. Admission and mixture of the charge of gas 
and air. II. Ignition. III. Explosion. lY. !^pansion. 
Y. Exhaust, or the discharge of - the gases and products of com- 
bustion. To these has been added in most modem engines a 
sixth, namely, YI. Compression. This cycle of work corresponds 
to each explosion, but not necessarily to each revolution; indeed, 
in many engines the number of revolutions and of explosions are 
independent of each other. The nature of these operations is as 
follows : — 

I. Admisflioii of the Gkis and Air to the Cylinder. — This 
was formerly supposed to be a complicated process, and great 
care was taken to provide separate valves for admitting the air, 
and conducting the charge to the cylinder. Experience has 
shown that the air enters freely through any aperture, which is 
usually placed in proximity to the gas admission valve. Gas, 
unless made specially on the spot, is admitted through a pipe 
from any ordinary gas main. In the older engines, admission of 
the charge is made through a slide valve, as already described, 
moving to and fro between the slide cover and the cylinder. 
The gas pipe communicates with a passage in the slide cover, 
and a hole in the slide valve leading to a cavity. As soon as 
the cavity is filled with gas, the movement of the slide brings it 
opposite a similar opening in the cylinder, through which the gas 



8 OA8 ENGINES. 

enters. In later engines admission is effected through ordinary 
lift valves. Before entering the cylinder, the gas usually passes 
through a chamber where it is thoroughly mixed with its proper 
proportion of air, admitted through a separate inlet. Much 
importance was attached to this process of mixing before the use 
of compression, and different methods were resorted to, either to 
mix the gas and air, or to keep them in separate layers, and 
stratify them as they entered the cylinder. It is now almost 
universally admitted that these arrangements do not influence 
the explosion, and that stratification does not take place in the 
manner supposed, owing to the compressive force exerted by 
the piston. The gas admission valve is usually connected to the 
governor, which regulates the quantity of gas entering, and 
consequently the number or strength of the explosions. 

II. Ignition. — The gases being admitted into the cylinder, 
the next operation is to fire or ignite them. This is usually a 
delicate process, because the return stroke of the piston exerts 
a considerable pressure upon the incoming charge, which may 
blow out the flame. The difficulty is increased in modem 
engines by the previous compression of the gas and air. Three 
methods of ignition are employed. 1. The electric spark. 2. A. 
gas jet constantly burning. 3. A tube maintained at a red heat 
by a gas burner. Electricity was the first means proposed and 
adopted for igniting the gases, and it is still largely used in 
French engines. A current of electricity passes along wires 
placed close to the valve or chamber admitting the charge of gas 
and air, sparks are continually formed and fire the mixture. As 
the electric spark is sometimes found to be precarious in action, 
missing fire, and the charge is not ignited, an electric hammer is 
used to obtain a continuous stream of sparks. With flame 
ignition the charge, after being admitted into the slide valve 
and mixed, is, in compression engines, carried past a -flame 
burning in a hollow of the valve. When the mixture is ignited 
the pressure of the burning gas often puts out the flame, and it 
is then relighted by an external permanent burner. The slide 
valve is held against the back of the cylinder, and is worked by 
an eccentric, but more often by a cam on the auxiliary or counter 
shaft driven from the main shaft. In England the most general 
method of ignition is, at present, by a hot tube. At a given moment 
the opening to this tube is uncovered, a portion of the charge at 
high pressure is brought in contact with it and fired, and explodes 
the remainder in the cylinder. The tube is kept at a red heat 
by a gas burner, and is easily replaced from time to time when it 
is worn out. Formerly these tubes were made of iron, and were 
"short-lived" as it is termed; but now very small tubes of 
platinum and other metals are used, which last much longer. 
In some of the older types of engines, where the charge is 
admitted at atmospheric pressure, the gas and air are drawn in 



GENERAL DESCRIPTION. 9 

at one end of the cylinder by the suction of the forward stroke 
of the piston. At a certain moment a small flap valve covering 
a flame burning on the outside of the cylinder is lifted by the 
pressure, the flame drawn forward, and the mixture thus ignited. 
Sometimes the piston itself in its out stroke, is used to un- 
cover the gas and air valves. In other engines the gases are 
ignited in a separate chamber; there is no explosion, but they 
enter the cylinder in a state of flame, and force the piston 
forward. 

III. and rv. Explosion and Expansion. — It is in the motor 
cylinder that explosion and expansion of the ignited gases almost 
always take place. To allow room for the compression and 
ignition of the charge, the clearance space is usually much larger 
than in steam engines, sometimes so large that it forms a 
separate chamber, into which the gas mixture is compressed. In 
the earlier types of gas motors, the charge was drawn in during 
the first part of the forward stroke, explosion taking place only 
when the piston had almost reached the middle of the cylinder. 
It was soon found that this tardy explosion greatly limited the 
number of expansions, and the work performed by the gases on 
the piston. Later engines were designed to procure the explosion 
as near the beginning of the stroke as possible, so as to allow the 
maximum volume of the cylinder for the expansion of the gases. 
In some vertical non-compression engines the clearance space 
is exceedingly small. Explosion of the gases takes place when 
the piston is at the bottom of its stroke, free of the crank and 
shaft, and drives it to the top of the cylinder. 

V. Exhausty or discharge of the gases. — Various methods 
are employed in gas engines for clearing the cylinder of the 
products of combustion. The unburnt gases are not at present 
utilised, like the exhaust steam in a condensing steam engine, 
and there is much conflict of opinion as to whether they should 
be completely expelled from the cylinder, or i)artly retained to 
mingle with the fresh charge. Most modem gas motors being 
single acting, or acting on one side of the piston only, the 
exhaust valve is seldom opened during the forward stroke. In 
some engines it only opens during half the return stroke, in 
others the whole of this stroke is utilised to expel the previous 
charge, while in a few engines a complete stroke, forward and 
return, is sacrificed to discharge the products of combustion, and 
cleanse the cylinder. Air under pressure is admitted to help 
the discharge in some modern engines. The exhaust valve plays 
an important part in a gas engine, because the high pressure in 
the cylinder is, of course, instantly reduced as soon as it is 
opened. Most gas engioes are so constructed that the unburnt 
gases are allowed to escape at a relatively high pressure and 
temperature, which are thus wasted instead of being utilised. 
This is one of the defects of these motors which engineers should 



10 GAS ENGINES. 

be most anxious to remedy. In some vertical engines the piston 
is forced up by the explosion and driven down by atmospheric 
pressure, a vacuum being formed below by the cooling of the 
gases. The opening of the exhaust valve at the bottom of the 
cylinder, by causing the air to enter, equalises the pressure 
above and below the piston, and checks its descent. In the 
earlier engines the exhaust was usually connected to the admis- 
sion and ignition valves, and one slide valve was made, during 
its motion to and fro, to uncover the three different openings. 
In others, and generally in the modern horizontal engines, the 
exhaust is under the cylinder, distinct from the admission 
valves, but worked from the same side shaft. 

VI. Compression of the charge. — The sixth operation in a 
gas engine is the compression of the gas and air before ignition* 
This is the most important modem improvement introduced 
into these motors. As compared with the other operations, 
compression has certainly great influence on the consumption 
of gas, and on the economical working of the engine. It is 
efiected in the following way : — A certain quantity of gas and 
air, in definite proportions, are admitted into the cylinder. 
Instead of being immediately ignited the mixture is compressed, 
and its pressure raised — that is, the volume of gas and air is 
forced into a much smaller space than before, either by the 
return stroke of the motor piston, or by that of a separate 
pump. If, for example, the charge occupied a space of 5 cubic 
feet, it is driven back by the piston till it occupies only, say 1 
cubic foot, or one-fifth the previous space, and the pressure ia 
raised five fold. The method usually adopted is to allow 
the piston to move out, and take in gas and air behind it 
till the whole cylinder is filled; the piston then returns, all 
the valves and ports being closed, and the mixture is driven 
into the clearance space and compressed. The advantages 
of this process are, that the particles of gas and air are 
forced much more closely together, and when they are ignited, 
their power of expansion has been found by experiment to be 
much greater. Nor do they part with their heat so quickly, 
being confined in a smaller space. Writers on the gas engine 
are unanimously of opinion that compression, previous to igni- 
tion, is the one great source of economy in gas motors, and this 
is confirmed by experiments. In the older non*compressing gas 
engines, it was always difficult to raise the pressure of the gases 
high enough to obtain much work on the piston. In modem 
compression engines, on the contrary, the expansive force of the 
gases is greater than can be properly utilised. 

The advantages of compression are — (1) The smaller size of 
cylinder required. In the early engines, to obtain an efiective 
working pressure, the cylinders were made large, and as much 
gas and air as possible admitted at a time, and even then the 



GENEBAL DESCRIPTION. 11 

pressure was often very low. But with engines using compres- 
sion, since the same charge occupies a smaller space, the cylinder 
can be made smaller. (2) Greater certainty and rapidity of 
explosion. It is true that to ignite the charge, when compressed, 
is more difficult than when it is at atmospheric pressure, but the 
particles of gas, being closer together, ignition proceeds more 
rapidly when once started, and a more vigorous explosion is 
obtained. The flame is easily and surely transmitted, permeates 
the whole mass almost instantaneously, and the entire force of 
the explosion is developed. (3) Greater economy of gasj because, 
inflammation being certain, a poorer quality of gas can be used. 
Not only may the quantity be smaller in proportion to air, but 
the weaker charge, if compressed, will still explode, even when 
farther diluted with the products of former combustion. (4) As 
a smaller cylinder is required for the same potoer, there is less 
wall surface to carry off the heat generated by explosion. 
(See Chapters xviii. and xix., where this subject is fully 
treated.) 

Compression is carried out in two ways. If the engine has 
only one cylinder, it takes place in the motor cylinder itself, and 
a complete stroke, to and fro, is generally sacrificed to obtain it. 
If a pump is added, the charge is compressed in it ; every stroke 
of the motor piston is then a working stroke, and the flywheel 
obtains an impulse at every revolution. The pump is worked 
from the crank shafl, and the six operations are divided between 
the two cylinders. The pump piston admits and compresses the 
charge, which is then exploded and expanded, and the products of 
combustion driven out from the motor cylinder. The two pistons 
work more or less simultaneously, and the forward stroke of the 
pump draws in the fresh mixture, during expansion of the charge 
in the motor cylinder. In other engines the pump is worked 
from a separate crank, set slightly in advance of the main 
orank. This cycle of operations is good, but its advantages 
are counterbalanced by the additional power required to drive 
the pump. Occasionally the gas and air are compressed into 
a separate receiver, and in a few engines the front part of 
the motor piston takes the place of the pump, and compresses 
the charge. 

Oiling, Ao, — Lubrication, starting, and regulation of the speed 
in a gas engine, each require a few words of explanation. Oiling 
the piston is a matter of much importance, and must be care- 
fully performed. The high speeds and temperatures at which gas 
motors work necessitate a continuous and skilful use of good 
mineral oil. In steam engines there is generally a certain 
amount of water, but the flames of a gas engine dry the internal 
surfaces, and unless oil is continuously applied, the cylinder soon 
becomes hot and begins to suffer. Hence the importance of 
internal lubrication in all gas engines. They are usually fitted 



12 GAS ENGINES. 

with a special apparatus for oiling the various parts automati- 
cally. 

Small gas engines can be quickly started, but with large 
powers the process is not always easy. The engine should be at 
work in a few minutes, and the inertia of the working parts has 
to be overcome. All the larger motors are provided with special 
means of starting, such as a receiver, into which a reserve charge 
of gas and air is compressed, or a handle or cam acting upon 
the exhaust valve to keep it open, thus reducing the pressure 
in the cylinder. Sometimes a small auxiliary gas engine is used. 
MM. Delamare-Deboutteville and Malandin claim to have intro- 
duced an entirely new system, first shown in their Simplex engine 
at the Paris Exhibition of 1889. Other devices for starting 
have lately been patented. 

Begulation of Speed. —To regulate the speed of an engine is 
rather a complicated process, and is effected in a variety of ways. 
Many different kinds of governors are used, though the majority 
are constructed on the principle of a weight acting by centrifugal 
force. A common type is the ball governor, but pendulum 
and air governors are also employed, while some governors are 
regulated by weighted arms or levers. The governor is generally 
in connection with the gas admission valve, but sometimes with 
the exhaust valve. The following are the usual methods of 
governing : — 

1. By regulating the opening, more or less, of the gas admisr 
sion valve. 

2. By completely cutting off the supply of gas during a certain 
number of strokes. 

3. By admitting more or less of the explosive charge at a 
time. 

4. By acting on the exhaust valve. 

Sometimes two or more methods are used with the same 
engine, according to the greater or less fluctuations in the speed. 
To vary the quantity of gas within certain limits is an effectual 
check. But if a smaller quantity be admitted than will ignite 
when mixed with air, a certain amount of unburned gas passes 
through the cylinder, and into the exhaust. The speed is reduced 
because there is no explosion, but the gas is wasted. To reduce 
the total quantity of the charge admitted may have a similar 
result, and give a weak stroke. The methods usually employed, 
therefore, in modern engines, when the governor acts upon the 
gas valve, is to cut off the supply entirely for a time, when the 
speed is too high. Air alone being admitted, there is no explo> 
sion. The indraught of pure air certainly tends to cool the 
cylinder, but it also thoroughly cleanses it of the products of 
former combustion, and a better explosion is obtained the next 
time a complete charge is admitted. This is the method adopted 
in the Otto and Atkinson engines* 



HEAT CYCLES. 13 

The tendency in modem gas motors is to simplify construction, 
and reduce the number of parts. Where only two lift valves are 
employed, one for admission, the other for discharge of the gases, 
the governor is usually connected to the exhaust. Under normal 
conditions of speed the suction of the forward stroke lifts the 
admission valve, and allows the charge to enter. This valve 
closes as soon as compression begins, during the return stroke, 
and remains closed as long as the pressure in the cylinder is 
greater than that of the ''atmosphere. The opening of the 
exhaust valve reduces this pressure, and when the gases are all 
discharged the automatic admission valve rises, and a fresh 
charge is admitted. If the speed be too great the governor acts 
upon the exhaust valve, keeping it closed. The pressure in the 
cylinder is maintained during the return stroke, the admission 
valve remains closed, and no fresh charge can enter until the 
governor has released the exhaust. 



CHAPTER IL 

HEAT "CYCLES" AND CLASSIFICATION OF 
GAS ENGINES. 

Contents. — Theoretical Cycle — Heat Efficiency — Classification of Gas 
Engines by Types, 

Theoretical Cycle. — The word "cycle," derived from the 
Greek, has the same signification as circle. As applied to 
mechanical motors it denotes a series of operations, at the 
end of which the working agent returns to its original con- 
dition, as at starting. The celebrated French engineer, Sadi 
Gamot, was the first to use the word in this sense, and for 
convenience it has been retained. Engineers have agreed to 
designate as a " cycle " the successive operations taking place 
in a heat motor, though these can never form what is termed 
a perfect or closed cycle. In every heat motor the same 
phenomena are repeated each time the gas, steam, or other 
working agent is introduced into the cylinder. In this sense, 
therefore, a given cycle of operations is periodically performed in 
these engines. The heat generated from a certain source passes 
into the engine cylinder to perform the work. That portion of 
heat which has not been utilised in the engine is transferred to 
a source of cold, and the difference between these two sources (of 
heat and of cold) represents theoretically the heat expended in 



14 OAS ENGINES. 

work. A working agent is necessary, to which the heat must be 
imparted, and from which it is withdrawn. 

The theoretical cycle imagined by Carnot, and called afier 
him, was a perfect cycle, that is, the heat generated was 
employed solely in doing work, and none was wasted. The 
medium or *' power agent," steam, gas, (be., was expanded, a 
piston was propelled, a given amount of work performed, and a 
given quantity of heat transformed into energy to produce this 
work. As the piston returned, it compressed the agent, re* 
storing by compression all the heat that had been expended in 
work. A peHect cycle was realised, since the whole heat 
was thus returned to its source, and the working agent to its 
original condition. In practice a perfect cycle is impossible. 
Whatever the agent employed, it can never really return to its 
original condition, and all the heat be refunded, because a 
considerable quantity is irrecoverably lost. Much heat will 
escape through the cylinder walls ; some will be wasted owing 
to imperfect expansion, passing out into the exhaust, and some 
will be expended in the friction of the engine. The more nearly, 
however, an engine approximates to the condition of a perfect 
cycle, and the more heat is expended in work on the piston, the 
greater will be the efficiency of the engine, and the higher the 
proportion between the useful work performed, and the heat 
received. 

Heat EfO-Ciency. — It has been shown that the higher the 
temperature of the mixture of gas and air in the cylinder pro- 
duced by combustion, the greater the pressure, and, therefore, 
the greater should be the force exerted on the piston. On the 
other hand, the lower the temperature of the discharged gases, 
the more heat will be expended theoretically in work. The 
heat efficiency is the ratio of heat turned into work to the total 
heat received by the engine. In practice this efficiency is 
always diminished by waste of heat through various circum- 
stances. Nevertheless, it is necessary to expand the gases as 
much as possible, because it is only by complete expansion that 
all the available heat can be utilised in doing work. If the gases 
are compressed by the return stroke of the piston, this heat will, 
theoretically, be refunded. Such a cycle of operations can, of 
course, be only obtained in theory, but in any case the more 
complete the expansion, the more the temperature and pressure 
of the gases discharged into the exhaust will be reduced. Less 
heat will be carried over from the cylinder, and more will 
remain to be utilised in it. Hence it is of the utmost import- 
ance to obtain as perfect a working cycle in a gas engine as 
possible. 

Types of Engines. — Different authors have adopted different 
methods of classifying the various types of gas engines. An 
obvious, but not very satisfactory, way is to divide them into 



CLASSIFICATION OP GAS ENGINES. 15 

horizontal and vertical. As a rule, engines for large powers are 
horizontal, and for small powers vertical ; but in England 
almost all sizes are made horizontal. There is said to be less 
vibration than in vertical engines, and greater power is obtained 
for a cylinder of the same size, but many foreign makers are of 
opinion that the advantages of vertical engines outweigh their 
defects. 

A more logical classification of gas motors, based on their 
internal working, is to divide them into engines drawing in the 
charge of gas and air at atmospheric pressure, and engines com- 
pressing the charge before ignition. This is the classification 
employed by the best authorities, and here adopted. In this 
way we get — 



Type { i{; 



Non-compressing engines ; and 
Compressing engines. 



Each of these types may be subdivided into Classes a and b. 

Type I., Cl<i88 a, includes non-compressing motors drawing in 
and igniting the charge at atmospheric pressure. The force of 
the explosion drives the piston forward, and the return stroke 
expels the products of combustion. This type of engine is also 
'made double-acting, giving an explosion or motor impulse per 
stroke on each side of the piston, and all the operations of admis- 
sion, ignition, and expansion are effected while the piston moves 
•once out and back again. The gases are discharged at the end 
«of the stroke. These double-acting engines are not much used ; 
the original Lenoir is the best example of the type. 

Type I., Class 6, also represents engines, chiefly vertical, which 
'draw in and ignite the charge at atmospheric pressure. The 
piston is forced up from the bottom of the cylinder, and performs 
no work, not being connected to the crsLnk. In the return 
stroke it is locked to the crank shaft, and descends only by 
the force of atmospheric pressure. This is the motor or working 
stroke. In a certain sense this class of engine is also double- 
acting, like Class a, the piston receiving two impulses per revolu- 
tion ; the first from the explosion of the gas below, the second 
from the pressure of the atmosphere above. The best represen- 
tative of this type is the Otto and Langen engine. In one 
variety, the Bisschop, the piston is driven up with great force, 
but is permanently connected to the motor shaft, instead of being 
firee during its ascent. 

Type II. comprises all engines using compression, and like the 
first type is divided into two classes. In Class a the whole cycle 
of work, including compression, takes place in the motor cylinder 
itself, and in order to effect the various operations in one 
cylinder, it is necessary to sacrifice one complete stroke. Com- 
pression IB obtained at the expense of power, and the piston 



16 OAS ENGINES. 

moves twice backwards and forwavds for every explosion or 
motor impulse given to the crank shaft. The well-known Otto 
engine is a typical example. 

In Type IL, Class 6, there is the same cycle of operations as in 
Class a, but instead of sacrificing a stroke of the motor piston, a 
special auxiliary cylinder is added. Admission of the charge in 
the pump, and expansion in the motor cylinder, are effected 
simultaneously ; the return stroke in the pump compresses the 
charge, while the motor piston drives out the products of com- 
bustion, as in the Clerk engine. 

There are very few engines which do not belong to either of 
these types. These are chiefly six-cycle engines, where the 
operations are similar to those described in Type II., Class a, but 
a third complete stroke is added, in order to cleanse the cylinder 
thoroughly of the products of previous combustion by what is 
called a "scavenger " charge of pure air. To avoid the difficulty 
of having only one motor stroke in six, these engines are some- 
times made double-acting — that is, an explosion takes place 
alternately at either end of the cylinder at every third stroke. 
Thus, there are two impulses for every three revolutions, as in 
the well-known Griffin engine. The action of these different 
types will be fully explained later on. 

It must be remembered that, in describing the to and fro 
motion of the piston of an engine, and its action on the crank, 
there are always two strokes, the forward or motor stroke, and 
the return or exhaust stroke. The forward or up stroke is 
towards the crank, the return or down stroke is away from the 
crank. The position of the piston corresponding to the outer 
dead point is when it is nearest to the crank shaft, and that 
corresponding to the inner dead point when it is farthest away 
from the crank. These terms will be used in this work. 

The following table exhibits the different types and their 
cycles. The engines are assumed to be horizontal, except when 
otherwise mentioned : — 

Type L— Non-compressing. 

Cycle of operations. 

1. Forward or motor stroke — ad- 
mission of charge of gas and 
air; ignition, explosion, ex- 
pansion. 

2. Return stroke — discharge of 
gases. 



Class a. 
One explosion each revolntion- 
cylinder. 

(Example, Lenoir.) 



Claa* b (vertical only). ( ^- ^P ?troke-^muwon of gas and 

«»lo«on «,r r«volnSon^ne I "'! . ^P"**"". exploMOn, ex- 

pansion. 

►own or nu 

of gases. 



One explosion per revolution— one » ^^ . _ 

i- J *■ \ pansion. 

(^p^ Atmospheric engine.) I ^ Do^ ormotor strok^diaoharge 



HISTORY OF THE GAS ENOINB. 17 

Type II.— Compressinsr. 

Cycle of operations. 
/I. Forward stroke — admiflsion of 
CUua a, I gas and air. mm 

One exploeion per two revolutions J \ 5;!!^?J'!;!:^!r/Ji^^^^^ 

icvlinder \ ^' '^^^^^'^ ^^ motor stroke— igni- 

(Example. Otto.) | , „ l'^"*' «Pl«f *<>»». expansion. 

v^A«xupic, v/i.irv.; I ^ Return stroke — discharge of 

\ gases. 

/ I. Forward or moicir stroke — in 
(^Ig^ 5 I cylinder— ignition, explosion, 

One cylinder and oie pump-one J !SJ.T!L' .IJJi £""P— ^»- 

explosion per revolution. ^ „ ^ "^"^ ^t*^ »°? **^:. , ,. 

*^ (Example. Clerk.) 2. Return stroke-m cyUnder-dis- 

^ ' ' ' I charge of gases; m pump — 

\ compression. 



CHAPTER IIL 
HISTORY OF THE GAS ENGINE. 

CoKTUVTS. — Early Combustion Engines — Gas Engines by HautefeniUe, 
Huyghens, Papin, Barber, Street, Lebon, Brown, Wright, Bamett, 
Drake, and others— Use of Town Gas for Engines— The ^arsanti and 
Matteucci Patents. 

Early Combustion Engines. — The earliest attempts to obtain 
motive power from heat were made by igniting inflammable 
powder, and utilising the force of the explosion thus generated. 
As a source of energy, this combustible powder was the first 
agent used ; it preceded the production of coal gas, or steam. 
Strictly speaking, cannons ai*e the oldest heat motors, and the 
principles on which they are constructed are identical with 
those of internal combustion engines. Heat is applied to 
explosive powder, and the expansion of the powder furnishes 
the motive force to propel a ball forward. In modem heat 
engines a piston takes the place of the ball. In the early days 
of mechanical science, the energy shown in the projection of a 
cannon ball seemed to afford a simple solution of the problem 
how to obtain power and motion by heat. But the power pro- 
duced by exploding powder in a cannon could not be used for 
practical work, because it was not generated continuously and 
regularly. To apply the expansive force of the gases given 
off during combustion, the combustible was exploded in a 
closed vessel, and made to act upon a piston. These early 

2 



18 GAS ENGINES. 

combustion engines, were the forerunners of modern gas motors, 
in which the power is also obtained by explosion. But though 
they were introduced nearly a hundred years before the first 
steam engine, they were soon abandoned, because it was found 
iuipossible to control the power generated. Steam was easier 
and safer to work with, and for more than a century explosive 
engines were wholly relinquished. 

Hautefeuille. — The first to propose the use of explosive 
powder to obtain power was the Abbe Hautefeuille, the son of a 
baker at Orleans. To him belongs the honour of designing, not 
only the first engine worthy of the name, but the first machine 
using heat as a motive force, and capable of producing a definite 
quantity of continuous work. As such, he may be considered 
one of the originators of heat motors. In 1 678 he suggested the 
construction of a powder motor to raise water. The powder was 
burnt in a vessel communicating with a reservoir of water. As 
the gases cooled after combustion a partial vacuum was formed, 
and the water was raised by atmospheric pressure from the 
reservoir. Another machine described by him in 1682 was based 
on the principle of the circulation of the blood, produced by the 
alternate expansion and contraction of the heart. Here the 
water was raised by the direct expansive action of the com- 
bustible gases given off by the powder when ignited. This was 
the first instance of a direct-acting engine, but no machine could 
be made strong enough to resist the spcismodic expansion of 
powder, as here proposed. 

HuyghenSy Papin. — Hautefeuille does not seem to have 
actually constructed the machines he designed ; but Huyghens, 
who was the first, in 1680, to employ a cylinder and piston, con- 
structed a working engine, and exhibited it to Colbert, the French 
Minister of Finance. The powder in this motor was ignited 
in a little receptacle screwed on to the bottom of a cylinder. 
The latter was immediately filled with fiame, and the air in it 
was driven out through leather tubes, which by their expansion 
acted for the moment as valves. The piston was forced by the 
pressure of the atmosphere into the vacuum thus formed. This 
is the action shown in modern atmospheric gas engines, but 
Huyghens found a difficulty in getting his valves to act pro- 
perly, and in 1690 an endeavour was made by Papin to improve 
upon his principle. By providing the valves with hydraulic 
joints, Papin contrived to make them tighter, and to obtain a 
better vacuum, but he found that, in spite of all his efforts, a 
fifth part of the air still remained in the cylinder, and checked 
the free descent of the piston. After various attempts to over- 
come this difficulty, he abandoned the use of explosive powder, 
and devoted his attention to steam. 

Barber. — For more than 100 years after these early attempts, 
all the efforts of scientific men and inventors were directed to 



HISTOBT OF THE GAS ENGINE. 19 

the study of steam, and its applications to produce power. Fop 
the time there was no other known agent that could compete 
With it. Gas extracted from coal had not yet been applied as a 
motive force in engines, and experience had shown that explosive 
powders were too dangerous, and too intermittent in their action, 
to be used with safety. The first to design and construct an 
actual gas engine was John Barber, who took out a patent 
(No. 1833) in 1791. Various circumstances contributed to the 
success of his invention. The steam engine already occupied an 
important position in mechanical science, thanks to the genius of 
Watt, Newcomen, Smeaton, and others. Workmen had by this 
time been trained, able to turn out and adjust with fair precision 
the different parts of an engine, though good tools were still 
hardly to be obtained. The distillation of gas from coal had 
already been discovered by Dr. Watson, though it was not till 
1792 that Murdoch, a Oornish engineer,* applied it to practical 
use. Barber made the gas required for his engine from wood, 
coal, oil, or other substances, heated in a retort, from whence the 
gases obtained were conveyed into a receiver and cooled. A 
pump next forced them, mixed in proper proportion with atmo- 
spheric air, into a vessel termed the " Exploder." Here they 
were ignited, and the mixture issued out in a continuous stream 
of flame against the vanes of a paddle wheel, driving them round 
with great force. Water was also injected into the explosive 
mixture to cool the mouth of the vessel and, by producing 
steam, to increase the volume of the charge. Barber's engine 
exhibits in an elementary form the principle of what is now 
known as combustion at constant pressure, but it had neither 
piston nor cylinder. 

Street. — ^The next engine, invented by Robert Street, and for 
which he took out a patent (No. 1983) May 7th, 1794, was a great 
step in advance. Inflammable gas was exploded in a cylinder and 
drove up a piston by its expansion, thus afibrding the first example 
of a practical internal combustion engine. The gas was obtained 
by sprinkling spirits of turpentine or petroleum at the bottom 
of a cylinder, and evaporating them by a fire beneath. The up 
stroke of the piston admitted a certain quantity of air, which 
mixed with the inflammable vapour. Flame was next sucked in 
from a light outside the cylinder, through a valve uncovered by 
the piston, and the mixture of gas and air ignited. The ex- 
plosion drove up the piston, and forced down the piston of a 
pump for raising water. In this engine many modern ideas 
were foreshawdowed, especially the ignition by external flame, 
and the admission of air by the suction of the piston during the 
up stroke, but the mechanical details were crude and imperfect. 

* The Hret practical application of gas to lighting purposes was in 1798 
at the Bonlton and Watt Soho Factory near Birmingham, where Murdoch 
was then employed. 



2U OAS ENGINES. 

Iiebon. — ^A great improvement in the practical application of 
gas engines was made by Philippe Lebon, a French engineer, 
who obtained a patent, Sept. 28th, 1799, and a second in 1801. 
The first was more particularly intended to describe the produc- 
tion of lighting gas from coal; in the latter he proposed to 
utilise this gas to drive a piston in an engine very similar to that 
designed by Lenoir, sixty years later. The inflammable gas and 
^' sufficient air to make it ignite'' were introduced separately into 
the cylinder on both sides of the piston, and the inventor pro- 
posed to fire the mixture by an electric spark. The machine was 
double acting, and the explosions of gas took place alternately 
on each side of the piston. The most striking peculiarity of the 
engine was the piston-rod, working not only the motor shafb^ but 
through it two pumps, in which the gas and air were compressed, 
before they entered the motor cylinder. Lebon also suggested 
that the machine generating the electric spark should be driven 
from the motor shaft. The excellent theoretical principles on 
which this machine had been designed were striking at that 
early period, and marked a new era in gas engines. More than 
sixty years elapsed before the great advantages Lebon had so 
clearly understood, of compressing the gas and air before igni- 
tion, were fully realised. The progress of mechanical science 
was perhaps retarded for many years by the assassination of this 
skilful engineer in 1804, before he had time to perfect the details 
of his invention. But in any case Lebon's engine was too much 
in advance of the times to have achieved immediate success. 
The manufacture of gas from coal was still in its infancy, and 
it was too expensive and difficult to produce to be used for 
driving an engine, while electricity was at that period so imper- 
fectly understood, that the ignition of the charge by an electric 
spark was alone sufficient to condemn the motor. 

Brown. — Lebon had many imitators, especially in France, but 
the next to invent a practical engine was an Englishman, Samuel 
Brown, who took out two patents, No. 4874, in 1823, and No. 
5350, in 1826. Brown's gas engines were the first actually at 
work in London and the neighbourhood, and also the first in 
which the pressure of the atmosphere was utilised as a motive 
power. The principle in both was the same, viz., to produce a 
partial vacuum in a cylinder by filling it with coal gas flames, 
which drove out the air ; the products of combustion were in- 
stantly cooled, and the vacuum thus obtained utilised to drive a 
piston. Instead of explosion, combustion of the gases was 
obtained by lighting them by a small flame as they entered the 
cylinder. The temperature of the latter was reduced by a water 
jacket, and water was injected to help the vacuum. In his first 
engine Brown employed two cylinders and pistons, connected by 
a beam. One piston was driven down by atmospheric pressure 
at one end of the beam, while the other, connected to the other 



HISTORY OF THE QAS ENGINE. 21 

«iid, was simultaneously raised. Part of the air escaped through 
▼alves in the piston, and tiie burning gases being instantly cooled 
by the water injected, condensation was produced, and a vacuum 
formed. In his second gas engine several cylinders were used, 
to obtain a continuous vacuum. The working action was the 
same, but the air escaped through the valve covers of the 
•cylinders, which were successively lifted. As in the other engine 
the gases were cooled, after combustion, by the injection of water. 
These engines were, however, cumbrous and difficult to work, 
and the expense of driving them with coal gas soon stopped their 
manufacture. A drawing is given in Robinson's Gha cmd 
Petroleum Engines, p. 105. 

Wright.— The next improvement in gas motors was the use 
of a governor to control the speed, introduced by Wright in his 
vertical double-acting engine, patented 1833 (No. 6525). 
Wright*s engine had one cylinder and piston, and one explo- 
sion was obtained alternately at either end of the cylinder. The 
piston and piston-rod were hollow, and the cylinder had a water 
jacket to counteract the intense heat of the double explosion. 
Ignition was obtained by an external flame and a touch hole. 
The gas and air were slightly compressed in separate reservoirs, 
before entering the motor cylinder ; their admission was regu- 
lated by a centrifugal governor, and the richness of the mixture, 
-or the greater or less quantity of gas passing the valve, varied 
with the speed. The design of this engine was carefully thought 
out) and its practical working details had not been overlooked, 
but it appears doubtful whether it was ever made. 

Bamett. — Five years later, in 1838, William Bamett, another 
Englishman, took out patents for three vertical engines. These 
engines contained so many novel and interesting features, and 
anticipated in so many ways the latest improvements of modern 
science, that they mark an important advance in the construc- 
tion of gas motors.* The first (patent No. 7615) had one 
working cylinder, single acting. Gas and air were drawn in and 
compressed by two pumps, and passed into a receiver below the 
motor cylinder, where they were mixed. During the down 
stroke of the pumps, while the charge was being forced into 
the receiver at a pressure of about 25 lbs. per square inch, the 
return stroke of the motor piston was discharging the burnt 
gases through the exhaust. All three pistons moved simul- 
taneously up and down. As the motor piston reached the 
bottom of its stroke, a valve at the side opened communication 
with the receiver. At the same time a revolving ignition cock 
immediately above the exhaust fired the mixture issuing from 
the receiver, and the burning gases entered the motor cylinder 

* A drawing of Bamett's engine is given in the Proceedings of the Inst. 
Mechanical mgineersy 1889. 



22 



GAS ENGINES. 



through the admission port, and impelled the piston upwards, as 
the crank passed the deiad point. 

The conical ignition cock, two views of whicli are shown at 
Fig. 1, is well designed, and has formed the type for many 
similar arrangements. It consists of a hollow revolving plug, A, 
in a shell, B. There are two openings, d communicating with 
the outer air, and e facing the cylinder ; the conical plug itself 




IQNmHQ 
COCK 



77 



Igniting Coek-£j'tti 



To C^/-../ [ ^■:■ 

TRAH8YEF::i [ ^ 






U 



Fig. 1. — Bamett's Engine Gas Ignition Cock— Longitudinal and 
Transverse Section, 



has only one port. At the bottom of the shell is a gas jet, which^ 
when lighted, is in the centre of the hollow plug. As the plug 
revolves, the slit in it is brought opposite the port, c, of the 
shell communicating with the cylinder, and part of the highly- 
compressed gases pass into the hollow plug, and fire the charge. 
The flame itself is blown out by the force of the explosion ; but, 
as the plug continues to revolve, the slit is brought to face 
port dy opening to the atmosphere, on the outside of which is a 
permanent second gas flame, H. Here the light is rekindled, 
each time it is brought round by the revolving plug. 

Barnett's second engine was double acting, but in principle it 
resembled the first. The third engine in its mechanical details 
differed very little from the gas motors now in use, and modem 
inventors have found it difficult to improve upon it in theory. 
One defect of Barnett's former engines was that, as the receiver 
or charging cylinder was never swept out by the piston, a por- 
tion of the gases of combustion was not displaced by the new 
compressed charge of gas and air, but always remained in it. 
Barnett proposed to overcome this difficulty by the use of an 
exhaust pump ; but in his third engine he abolished both pump 
and receiver. The gas and air were compressed in separate 
cylinders, and delivered direct into the motor cylinder. The 
pump shaft was driven by a pair of wheels from the motor crank 
shaf^ and the pumps made twice as many strokes as the motor 



HI8T0BT OF THE QAS ENGINB. 23 

piston. * The engine was doable acting, and the compressed gas 
and air were admitted alternately to each face of the piston. 
The action of the engine and exhaust valve was as follows : — 
The piston being at the bottom of the cylinder, the compressed 
charge below it was fired by the ignition cock in the same way 
as in the single-acting engine. The piston drove up before it the 
products of combustion from the last explosion, and discharged 
them during the first half of the stroke into the atmosphere, 
through a port in the centre of the cylinder. As this port was 
closed by the piston, the pressure below it fell to that of the 
atmosphere. The gas and air, already compressed in the pumps, 
were then delivered into the top of the cylinder, and still further 
compressed by the continued up stroke of the motor piston, 
together with a certain quantity of the gases of combustion left 
from the former charge. The mixture at high pressure was 
fired, and the piston driven down by the explosion, forcing out 
the burnt gases below it in the first part, and compressing the 
residuum with the fresh charge during the second part of the 
stroke. At the bottom of the cylinder a fresh explosion took 
place, and the cycle was repeated. 

Barnett may justly claim the honour of having been the first 
to introduce compression of the gas and air in a practical shape, 
as now used in gas engines. Lebon, it is true, proposed to 
compress the mixture slightly before igniting it, but he did not 
work out the details, or put his method to the test of actual 
practice. There are three points distinguishing Barnett's from 
previous engines. Ignition was effected at the dead point, and 
gave an impetus to the crank and piston during the whole 
forward stroke; the gas and air were compressed befi)re ignition; 
and part of the products of combustion were utilised to increase 
the pressure in the motor cylinder. It is generally admitted, 
however, that Barnett did not recognise the merit of his own 
suggestions. Experience has shown that compression is essential 
to economy in a gas engine, and ignition at the dead point is 
also important, but Barnett apparently used both, without 
realising their value. Nor did he seem aware of the difiiculties 
of disposing of the gases of combustion, a point on which later 
inventors have differed so widely ; for although he attempted to 
discharge the greater part, he evidently did not regard the 
presence of the remainder as affecting the explosion of the 
mixture. In the opinion of Mr. Olerk, insufiicient expansion 
was the fault of the later Barnett engine, a defect which it has 
hitherto been found impossible to avoid in double-acting 
engines. 

Two or three smaller engines were designed during the next 
twenty years, although none of them seem to have been con- 
structed. In 1841 Johnston described a motor in which he 
proposed to introduce oxygen and hydrogen gas into the cylinder. 



24 QAS ENGIMBS. 

and fire them. The force of the explosion drove up the piston, 
and a vacuum was produced by the condensation of the gases. 
The same process was repeated at the top of the cylinder, and 
the piston was forced down by the fresh explosion, ascending 
and descending alternately in a vacuum. The great cost of 
these gases was sufficient to condemn Johnston'3 project of what 
may be called a condensing oxy-hydrogen engine. 

Between the years 1838 to 1860 a large number of patents 
were taken out both in England and France, but most of the 
engines never advanced beyond the specification. Sixteen 
patents were granted from 1850 to 1860. Among the engines 
designed were — ^Ador, 1838; Robinson, 1843; Reynolds, 1844; 
Perry, 1845; Brown, 1846; Roger, 1853; Bolton and Webb, 
1853; Edington, 1854, and others. A few contain novel though 
impracticable features, and are described below, because, as 
inventions, they are interesting. 

Drake. — An ingenious gas engine was exhibited by Dr. Drake 
at Philadelphia in 1843; the English patent (No. 562) was taken 
out in 1855 by A. Y. Newton. In this horizontal engine 
ordinary lighting gas was used, mixed with nine or ten times its 
volume of atmospheric air. Much care was taken to admit the 
mixture in proper proportions, and the supply of gas was regu- 
lated by valves controlled by a governor. The charge entered 
the cylinder at atmospheric pressure, and was fired by a small 
tube kept' at white heat by an external flame. The force of 
the explosion drove out the piston, giving a maximum pressure 
of about 100 lbs. per square inch ; the mean effective pressure 
during the stroke, with a speed of sixty revolutions, and twenty 
indicated H.P.,* was about 36 lbs. per square inch. The cylinder 
had a water jacket, and the piston was hollow. The engine was 
originally double-acting, but when used in America it worked 
single-acting only; the valves on one side of the piston were 
kept always open to the atmosphere. The force of the explosion 
was very great, and owing to defective construction was chiefly 
directed against the cylinder heads, shaking the whole machinery. 
The engine was afterwards modified, and worked chiefly with 
petroleum. 

An important suggestion, which has since formed the basis of 
many successful engines, was made by Degrand in 1858. He 
proposed to compress the charge in the cylinder by the motor 
piston, but the idea was abandoned at the time, because Degrand 
required a large cylinder to obtain previous compression. 

None of these engines worked successfully, and many were 
never made. One cause of their failure, which has not been 
much noticed by writers on the subject, was the difficulty 

♦ H.P. = Horse-Power. 
I.H.P. = Indicated HorM-Power. 
B.H.P. = Brake Horse-Power. 



HISTORY OF THE GAS ENGINE. 25 

of procuring lighting gas from coal, except in a few of the 
large towns. The art of distilling gas was still in its infancy, 
and possibly few of the early inventors foresaw the day when 
gas woald become a household commodity, as easily obtained, 
even in small villages, as water. Sixty years ago, it was costly 
and seldom available, and numerous substitutes, none of them 
very practical, were proposed. As gas was more extensively 
made it became much cheaper; engineers saw in it a new motive 
power, concentrated their efforts to utilise it, and finally achieved 
success. Another mistake made by the early inventors of gas 
motors was, that they attempted to supplant, instead of to sup- 
plement, the steam engine. They did not perceive the real 
advantages of the gas engine as a motor for small powers, but 
tried to make economical engines up to 20 H.P., or 50 H.P., 
before the constructive details were thoroughly understood. A 
third difficulty in constructing practical gas engines lay in the 
ignorance prevailing on the subject. They were designed too 
much on the lines of steam engines. Most of the latter were 
double acting, and the inventors of the day could not divest 
their minds of the idea that a similar method, if adopted with 
gas, would give the same favourable results. Experience has 
shown that the action of gas in a cylinder is very different 
from that of steam, and that gas engines must be differently 
designed. 
Barsanti and MatteuccL — At about this period, however 

gSGO), and especially after the production of the Lenoir and 
ugon engines, three defects had come to be recognised as the 
inevitable results of an explosion at each to and fro stroke of the 
piston. The heat generated was so great that it had to be car- 
ried off as quickly as possible, and even with water jackets to 
the cylinder, parts of the engine sometimes became red hot. It 
was also impossible, in a double-acting engine, to compress the gas 
and air before ignition ; and lastly expansion of the gases was 
greatly limited. The stroke of the piston was too short to utilise 
to the full the expansive force produced by the explosion, and 
the products of combustion were discharged at a pressure much 
above atmospheric. In this way, almost all the heat generated 
by the ignition and explosion of the gases was wasted. Many 
experiments were made, and many engines constructed, before 
it was realised that the greater the amount of heat utilised by 
doing work on the piston, the lower would be the temperature 
and pressure of the gases at discharge, and the less heat would 
be wasted. The next engine, invented by two Italians, Barsanti 
and Matteucci, showed a better knowledge of the principles of 
economy. In it a distinct step in advance was made, and an 
important principle exhibited for the first time in practice, namely, 
the use of a free piston, and unchecked expansion of the charge. 
Por this reason Barsanti and Matteucci's motor deserves attention 



26 



GAS ENGINES. 



and study, though, like many others, it was not a practical work- 
ing success. 

In this vertical atmospheric engine, as in Barnett's first motor, 
the idea of a cylinder closed at both ends is abandoned. Ex- 
plosion takes place at the bottom of the cylinder, the piston is 
free and not connected during the up stroke to the crank shaft. 
The motive force is exerted only during the down stroke. A 
vacuum being produced below tlie piston by the cooling of the 
exploded gases, it descends by the atmospheric pressure above it, 
plus its own weight. This is the first example of an indirect 
vacuum engine with free piston. Gas and air are admitted at 
atmospheric pressure through slide valves into the cylinder, 
where they are partly mixed, and fired by an electric spark. 
The piston is driven up by the explosion, without any check to 
its velocity, or to the expansive energy of the gases. Before it 
reaches the top of its stroke the explosive force is expended, but 
it is still urged upwards by the weight of the different parts 
in motion. It is there brought to a stand by the pressure of the 
atmosphere, and begins to descend ; a rack on the piston-rod 

catches into a cog-wheel, driving 
the motor shaft with it in its 
descent, and giving the positive 
or useful work performed by the 
engine. 

Two patents were taken out 
by Barsanti and Matteucci in 
England, the first in 1854, the 
second in 1857. In the first the 
free piston was supplemented by 
a lower auxiliary piston imme- 
diately below it in the same 
cylinder. An outline drawing of 
the engine is shown at Fig. 2. 
A is the cylinder and P the 
motor piston; p is the auxiliary 
piston, S the fiat slide valve 
actuated by a lever, F, connected 
with the rod E of the auxiliary 
piston, which passes through the 
bottom of the cylinder. The 
crosshead at E is attached by 
two levers, not shown in the 
drawing, to the wheel D and the 
crank J, driven from the main 
shaft, butnot re vol vingso rapidly. 
As soon as the free piston P 
has reached its lowest position p begins to descend, and air is 
admitted between the two pistons through the passages a, h^c of 




t^Iafn 



Fig. 2.— Barsanti and Matteucci's 
Gaa Atmospheric Engine. 



BISTORT OF THE GAS ENOIME. 27 

the slide valve S. As the auxiliary piston descends, the slide 
valve is lowered with it by the lever F, the air port a is closed, 
and the gas port d uncovered, admitting gas to the cylinder 
between the pistons, through dy b, and c. The slide valve next 
shuts off d, when the mixture is fired by a series of electric 
sparks, the circuit being put on by the lever F. The piston P 
which has been at a stand, is now projected upwards, and p is 
forced still lower, driving out the products of combustion below 
it through the openings i t in the bottom of the cylinder. The 
pressure in the cylinder beneath the free piston is now below 
atmosphere, the valves 1 1 close automatically, the channel / is 
uncovered, and as the piston rises, communication is established 
between the contents of the cylinder above and below the 
piston p, through /, e, and 6. The working piston descends in 
the vacuum, driving out the exhaust, and the same process is 
repeated. 

The arrangement of the catch is novel and ingenious. The 
rod of the free piston F carries a rack, and as soon as the piston 
begins to descend, the rack gears into the toothed wheel L, 
running loose on the main shaft K. The wheel L has a pawl C. 
As the rack falls, and drags L round to the right, the spring s 
presses the pawl C into the teeth of the ratchet wheel B, which 
is keyed on to the main shaft K, and causes B and therefore K 
to rotate to the right. When the piston rises, the main shaft 
continues to turn to the right, but the movement of the wheel L 
is reversed ; it revolves to the left with the up stroke of the 
piston, and 0, slipping past B, loses connection with the main 
shaft. To steady the motion of the engine two working cylin- 
ders and pistons were employed, driving the shaft alternately, 
and the flywheel also helped to regulate the speed. The rack 
and clutch gear form the basis of similar methods for utilising 
the down stroke in atmospheric engines, and have, with the free 
piston, been repeated with modifications in the Otto and Langen, 
GiUes, and others. In the Barsanti and Matteucci engine the 
modem slide valve was also first introduced, the main con- 
struction of which has since been retained, although the valve 
is often differently driven. 

The second engine, patented by Barsanti and Matteucci, had 
the long vertical cylinder and piston with rack, but the auxiliary 
piston was abolished. The slide valve was worked by a valve 
rod, and the details were much simplified. There was an 
auxiliary as well as a motor shaft, both having pawls acting 
upon the rack. When the piston is in its lowest position, it is 
slightly raised by the pawl upon the main shaft. The valve rod 
is lifted at the same time by a smaller pawl on the auxiliary 
shaft, and air admitted through an outlet which serves also for 
the exhaust. As the piston and slide valve rise, the latter shuts 
off the air, and opens the gas port. The piston next overruns 



28 GAS EN6INKS. 

this port, the mixture in the cylinder is fired by an electric 
spark, and the piston driven up as before, free of the main sfaafi. 
During its descent the piston-rod engages in the wheel and 
ratchet on the main shaft, causing the whole to revolve during 
the down stroke. As soon as the pressures above and below the 
piston are equalised, and its descent arrested, it is caught by the 
other pawl, and held down, to drive out the products of combus- 
tion. The movement of the slide valve is regulated in the same 
way by the two smaller pawls on the main and auxiliary shafts, 
acting on two projections on the valve-rod. The piston having 
reached its lowest position, is raised by the pawls upon the main 
shaft, to admit a fresh charge. 

In this engine a much better and freer expansion was afforded 
to the combustible gases than had hitherto been obtained. In 
fact there was no check to their expansion, except the weight 
of the piston, <Sec. But, notwithstanding its excellent cycle, this 
motor was never in the market, probably because the work- 
ing details and the mechanism were defective. That the main 
lines on which it was constructed were good, is proved by the 
fact that they were adopted and successfully put in practice by 
Otto and Langen, though the German engineers appear to have 
designed their motor independently. The fundamental principle 
of the Barsanti and Matteucci engine, to utilise the whole force 
of the explosion in as complete expansion as possible, was excel- 
lent, and has not been improved upon. Few modem inventors 
have been able to approach as closely the conditions of a perfect 
theoretical cycle. 



CHAPTER IV. 
HISTORY OF THE GAS E}iGUiE-{Cantmued). 

Contents. — Period of Application — The Lenoir Engine — Tresca's trialB — 
Hugon's Kngine,and '1 resca's experimenta — Siemena, Schmidt, Million — 
Bean de Rochaa' Cycle of Operations. 

About the year 1860 the importance of the gas engine had 
become widely recognised. Great as was the perfection to 
which steam engines had been brought, it was felt that they 
did not, and could not, supply the various requirements for an 
economical motor. The necessity for some other kind of engine 
had already been pointed out by Cheverton in 1826. In a 
letter to the Mechanic's Magazine he says — '^ It has long been a 
desideratum in practical mechanics to possess a power engine, 
which shall be ready for use at any time, capable of being put in 
motion without any extra consumption of means, and without a 



HISTORY OF THE GAS RNGINE. 29 

loss of time in its preparation. These qualities wonld make it 
applicable in cases where but a small power is wanted, and only 
occasionally required. They are so numerous, and the conse- 
quent saving of human strength would be so great, that the 
advantages accruing to society would be immense, if even the 
current expense were much greater than that of steam." No 
words could better describe the present advantages of the gas 
engine. 

Applioation. — In the history of gas motors three periods may 
be <^tinguished — 1, Invention; 2, Application; 3, Theoretical 
and practical improvement. The first, the period of invention, 
was over. Hydrogen, inflammable powder, and other explosives 
were no longer used in engine cylinders, and gas was already 
recognised as the most suitable medium, next to steam, for 
utilising heat as a motive power. In the construction of the 
gas engine, much had been achieved by mechanical ingenuity. 
All the parts had been designed, and the details thought out. 
Scarcely a single improvement has been suggested in modern 
engines, which may not be found in the drawings of Lebon, 
Barber, Street, Bamett, and others. In the words of Professor 
Witz — "The gas motor had been invented; the problem was 
how to make it a working success." It is here that we enter 
on the second period, of Application. That time, too, has now 
passed. Practical experience has long been brought to bear on 
the construction of the ^ras engine, but the maximum utilisation 
of the heat is still a problem of the future. 

Lenoir. — From this point of view, the honour of having 
invented and introduced the first practical working gas engine 
justly belongs to Lenoir. His specifications set forth no new 
features, but he was able, not only to make his eogine work, 
which no one had hitherto succeeded in doing, but to work 
rapidly, silently, and, as at first supposed, more economically 
than steam. Cost and space were reduced by the absence of a 
boiler, and nothing could apparently be simpler, nor better suited 
to drive machinery of every kind, than the new motor. Its 
success was undoubted, and every one was eager to use it. The 
partisans of Lenoir loudly and confidently afiirmed that the reign 
of steam was over, and that it would be immediately superseded 
by gas. The economy attributed to the Lenoir motor, and exag- 
gerated by report, increased its popularity. Although made at 
a time when very little was known of the theory of the gas 
engine, and its action was imperfectly understood, the new motor 
was credited with an economy in the consumption of gas which 
inventors, after thirty years of study and experience, have hardly 
been able to realise. 

Lenoir took out his first patent in France, Jan. 24, 1860 ; in 
England, No. 335, Feb. 8, 1860. The engines were made by 
M. Hippolyte Marinoni, a French engineer, whose mechanical skill 



30 GAS ENGINES. 

andoubtedlj contributed to their success. During the first year 
one was constructed of 6 H.P. and another of 20 H.P., and so 
great was the demand that, in five years, between three and four 
hundred motors were made in France, and a hundred in Enghuid. 
This is a large number, considering that the gas engine was still 
on its trial. A Lenoir engine was used to propel a boat on the 
Seine, and for twenty years water has been pumped by another 
at Fetworth. The construction was undertaken by the Beading 
Iron Works in England, and the Oompagnie Lenoir at Paris. 
In 1863 the patent of the latter was acquired by the Compagnie 
Parisienne de Gas. 

The usual reaction from such undue praise and indiscriminate 
adoption of the new engine followed. The chief cause of its 
sudden fall in popular esteem was the discovery, that it consumed 
much more gas than it was said to do. Some of the advocates of 
the new motor claimed a consumption of 31*7 cubic feet of gas 
per H.P. per hour ; others instituted a comparison with the 
steam engine, to the disadvantage of the latter. Thus, it was 
asserted that the cost of working a 4 H.P. steam engine in 
Berlin was 6s. 6d. per hour ; for a Lenoir engine of the same 
power it was said to be about half. These figures were greatly ex- 
aggerated. In practice the Lenoir engine consumed from 88 
to 105 cubic feet of Paris gas per H.P. per hour. A brake 
experiment gave a mean of nearly 106 cubic feet, and this was 
about the average consumption for small powers. The quantity 
of water required for the cooling jacket was considerable. The 
heat generated was so great that, unless the engine was copiously 
oiled, the working parts were injured, and it was brought to a 
stand. Hence it was sarcastically said that " the Lenoir motor 
did not require heating, but oiling.'' 

In the reaction which now set in most of the Lenoir engines 
were at once abandoned ; some were broken up, and a few even 
turned into steam engines. This sweeping condemnation was 
hardly justified. The engines possessed many advantages, which 
were as completely overlooked as their defects had been at first. 
They were easy to transport, to fix, and to set to work, and, when 
constructed for small powers, were very useful in many cases for 
superseding manual labour. If the consumption of gas was 
heavy, the original cost of construction was said to be less than 
that of a steam motor. The engine could be started at a 
moment's notice, and when not running, no expense for gas 
was incurred, while it has hardly been surpassed for silent, 
smooth, and regular working. But these were not the chief 
merits of the Lenoir engine. It was the first to compete with 
steam for small powers, and to familiarise the public with the idea 
of obtaining motive power from gas. The advantages of these 
motors were so great and so patent that, when the Lenoir was 
gradually superseded, it was replaced by other engines driven by 



HI8T0BT OF THE GAS ENQINB. 31 

gas. Its very defects acted as a stimulus to fresh efforts, and 
kept the subject before the minds of inventors. Once accus- 
tomed to the easy action of a gas engine, in which it was only 
necessary to turn a valve on the gas main, and another on the 
water supply, to set the machine in motion, many people refused 
to return to the laborious process of generating steam in a 
boiler. 

Lenoir was himself fully alive to the faults of his engine, and 
continually studied to overcome them, but he started from a 
wrong basis. He attributed the extravagant consumption of 
gas to the rapidity of explosion, which affected the action of the 
engine injuriously, by producing a sudden rise and fall in the 
pressure. In common with later inventors, he endeavoured to 
diminish the force of the explosion, and to obtain a slower com- 
bustion of the gases by stratification, and in a second patent, 
No. 107, January 14, 1861, he also proposed to inject a little 
water into the cylinder. In his opinion it would help to lubri- 
cate the engine, take up by evaporation some of the heat 
developed, and, above all, cool the charge and retard explosion. 
The injection of steam into a gas engine cylinder has since been 
often suggested, and put in practice, without producing any 
real economy — its advantages and defects will be considered 
later on. Lenoir himself does not seem to have carried out 
his proposal. 

The much vaunted and much abused Lenoir gas engine resem- 
bled in construction a double-acting horizontal steam engine, and 
the gas was ignited electrically. Gas and air were admitted at 
both ends, drawn in by the piston during the first part of the 
stroke, and then fired and expanded. Admission of the charge 
was cut off, either at half stroke or a little later. As ignition 
with the electric spark was not always instantaneous, it occa- 
sionally happened that the piston had passed through a con- 
siderable portion of the stroke before explosion occurred, and 
incomplete expansion was the result. The cylinder, both covers, 
and the chamber into which the gas was admitted, were water- 
jacketed, and the circulating water was used over and over 
again. 

In the original drawing of the engine, shown at Fig. 3, A is 
the motor cylinder, in which is the piston P. The piston-rod 
works the connecting-rod C, and crank shaft K, through the 
crosshead D. Two eccentrics, G and H, on the crank shaft, 
work two flat valves, S and Sj, on either side of the cylinder. 
The slide valves, S S, admit gas and air into the cylinder, and 
those at S^ S^, allow the products of combustion to escape. The 
latter each contain one exhaust port ; and these are brought into 
line with the exhaust openings shortly before the end of the 
stroke, to let out the gases of combustion, and close over them 
as the fresh mixture enters. Through the exhaust ports the 



32 



GA8 ENGINES. 



gases pass into a discharge pipe, and thence into the atmosphere. 
The slide valves, S S, perform the functions of admission and 
distribution, and the two chambers, L L, are filled with gas. 




HISTORY OF THE GAS ENGINE. 



33 



These valves are made with small cylindrical holes ^ inch in 
diameter, alternating with larger apertures ^ inch by ^ inch 
diameter. The gas enters from L through these holes, while the 
air is admitted through the ends of the slide valves, which are 
open to the atmosphere, and passes through the apertures in the 
proportions of about 1 of gas to 12 of air. This arrangement of 
comb-shaped grooves and passages is continued throughout the 
whole thickness of the slide, and the effect is to cause the gas 
and air to flow to the cylinder in separate streams. By thus forc- 
ing them to enter without mingling, a better stratification of the 
charge was supposed to be obtained. Lenoir's idea seems to have 
been that the ignition flame would be propagated from one 
stratum of gas to the next, through the dividing layers of air, but 
this appears doubtful, and it has been questioned whether any 
real stratification of gas and air takes place. At either end of 
the cylinder is a small projection at 6 and 6,, to which wires are 
attached from the coil and electric battery, M. 

The action of the engine is as follows : — The exhaust valves 
being closed when the piston is at the extreme end of the stroke, 
as shown in the drawing, the energy of the flywheel is sufficient 
to carry it forward. The air port, which is very large to prevent 
throttling, is already slightly open, the gas valve now opens, and 




Fig. 4~Lenoir Engine— Section of Cylinder. 

the charge is mixed in the main port of valve S before being 
drawn into the cylinder by the forward stroke of the piston. 
Meanwhile the pressure on the other side of the piston has been 
reduced to that of the atmosphere. Before the admission valve 
is completely closed the electric spark fires the mixture, and the 
piston is thus propelled forward to the end of the stroke, the 

3 



34 GAS ENGINES. 

pressure rising to 5 or 6 atmospheres, but the action of the water 
jacket cools the cylinder, and reduces the pressure. The exhaust 
valve has a slight lead, and opens a little before the end of the 
stroke, allowing the gases of combustion to escape at a pressure 
of 1 '5 to 1 '8 atmosphere. The same process is repeated during 
the return stroke. A certain proportion of the gases of com- 
bustion are always left in the cylinder, but their pressure is low, 
and the clearance spaces are very small. The temperature of the 
escaping gases is given by Professor Schottler. at about 200** 0. 
In an experiment by Tresca it was 220** 0. 

Fig. 4 gives a sectional plan of the cylinder, in which the 
admission of gas and air are slightly modified ; the parts are 
lettered as in Fig. 3. Here the main admission port is open to 
the atmosphere, and is covered with a perforated brass plate, 
which extends downwards, so as also to cover the gas port. As 
the gas enters, it is forced to pass up and down through small 
holes in the metal plates, and to mix thoroughly with the air 
before entering the main port, but this arrangement, like that 
already described, was not found to work quite satisfactorily. 

Like most of the early gas engines, the Lenoir was ignited by 
an electric spark, as shown at M, Fig. 3. A battery with two 
Bunsen cells, connected by a Kuhmkorff induction coil, and an 
electric hammer, produces a continuous stream of sparks. The 
oontact maker K is in connection with the crosshead D, and 
piston-rod, through which the negative current passes, and the 
mass of the engine is negative. The positive current passes 
through wires insulated in porcelain tubes, leading from the two 
ends of the contact maker to the two projecting points, b and b^, 
at each end of the cylinder. Contact is formed alternately 
between them by a projection moved to and fro by the cross- 
head. Although carefully designed, this apparatus was open to 
some of the usual defects of this system of ignition ; the points 
occasionally missed fire, and the spark was retarded, or failed. 

The speed of the engine was regulated in the ordinary way by 
a centrifugal governor acting on the gas admission valve, and the 
supply of gas was wholly cut ofi^ as soon as the speed exceeded 
the normal limits. The oiling was always defective. Ordinary 
lubrication by hand was at first used, but this was soon found 
insufficient to counteract the great heat generated in a double- 
acting gas engine. The piston frequently became red hot and 
heated the incoming charge before ignition, a defect which 
later inventors have endeavoured always carefully to avoid; 
and the temperature was so high that, unless frequently and 
•copiously oiled, the engine would not work. 

It is always less difficult to start a non-compressing gas engine 
fired electrically than a compression engine, and the Lenoir 
motor was very easily set in motion. The flywheel was turned 
by hand, and the piston moved forward, drawing in the explosive 



HISTORY OF THE QAS ENGINE. 35 

mixture. At the same moment electric contact was established, 
a spark fired the charge, and the explosion drove out the piston 
over the dead point, after which the engine worked automatically. 

The earliest trials on record of any gas motor are those made 
by Tresca in 1861 on the Lenoir engine. The first experiments 
were on an engine of I H.P. with a speed of 130 revolutions per 
minute. The proportion of gas to air was one-tenth, the maxi- 
mum pressure obtained 4*87 atmospheres, the consumption of 
Paris gas was 112 cubic feet per H.P. per hour. In a second 
trial of a 1 H.P. engine, the quantity of gas used was reduced to 
96 cubic feet per H.P. per hour, or about four times the average 
present consumption. The maximum pressure in the cylinder was ' 
4*36 atmospheres, number of revolutions 94, and the proportion 
of gas to air 1 to 7^. In both engines more than half the total 
heat was carried on in the water jacket, and Tresca calculated 
that only 4 per cent, was utilised in useful work, the remainder 
being discharged with the exhaust gases. The average con- 
sumption of oil was about '10 lb. per hour. Other experiments 
were made by Lebleu, Eyth, and Auscher, and an important 
trial was carried out by Mr. Slade in America. The engine 
tested was about 2 H.P., and ran at 45 and 50 revolutions per 
minute. The maximum pressure in the cylinder was 63 lbs. 
above atmosphere ; the consumption of gas was not determined. 
Fig. 5 shows an indicator diagram of the Lenoir engine. 

Twenty-five years later Lenoir, who was incessantly endea- 
vouring to perfect his invention, brought out a single-acting 
compression engine, using Beau de Kochas' four-cycle. It will 
be described among modern motors. 

The success of the Lenoir engine produced a host of imitators 
and rivals, several of whom set up a prior claim to the invention. 




Fig. 5. — Lenoir EngiDe — Indicator Diagram (Slade). 

Keithmann, a watchmaker at Munich, declared that he had 
designed an engine similar to Lenoir's, for which he had taken 
out a patent, Sept. 11, 1858. It was described in the "Bayerische 
Kunst und Gewerbeblatt," but, if ever made, it never reached 
a practical stage. A more formidable opponent was Hugon, the 
Director of the Paris Gas Company, whose original patent also 
dates from Sept. 11, 1858. It is certain that Lenoir worked 
independently, and that his invention as a practical engine was 
the first in the market. 



36 OA8 ENGINES. 

Hugon. — Hugon's vertical gas engine did not appear till 
1862. His original intention, as stated in his first patent, was 
to construct an atmospheric engine and utilise a vacuum. He 
abandoned it in favour of a direct-acting engine similar in 
principle to Lenoir's, which he patented in France, March 29, 
1865 ?No. 66,807). In this engine Hugon introduced several 
novelties and improvements. Flame ignition was substituted 
for electricity, and a small quantity of water was injected into 
the cylinder at every stroke, to cool and lubricate it, and to 
economise the consumption of oil. The arrangement of the slide 
valves, although complicated, was ingenious. The flame to ignite 
the charge was carried to and fro in a cavity inside the valve, 
and Hugon's engine afforded the first practical illustration of 
this method of ignition, afterwards so generally used. The 
defects of Lenoir's engine were the great heat generated, retarded 
ignition, and insufficient expansion of the charge. These faults 
Hugon hoped to avoid by flame ignition and the injection of 
water, and it cannot be denied that his engine was superior in 
economy, and in certainty and rapidity of explosion. Firing the 
gases by a permanent flame was an improvement on electricity 
as then employed, but the consixnption of gas was still very 
larga The engine did not find much favour, even in France, 
nor supersede the Lenoir to any great extent, though it worked 
smoothly and, except from the economical point of view, satis- 
factorily 

In this vertical, single cylinder, double-acting engine, air and 
gas are admitted, as in the Lenoir, on both sides of the piston 
at atmospheric pressure. The piston F and piston-]X)d in 
cylinder A drive the shaft through a forked connecting-rod and 
crank, as shown in Fig. 6, taken from Schottler's* careful descrip- 
tion of the engine. An eccentric on the same shaft works the 
rubber gas reservoir 0, from which the gas is pumped under 
slight pressure through the pipe a to the cylinder. A smaller 
gas reservoir, D, supplies gas for the ignition flames. The valve 
rod, actuated by a second eccentric on the crank shaft, works the 
two admission valves, S and S.. A small pump, B, is driven 
from it, and injects water into the cylinder through the supply 
pipe d and the small openings d^ and d^. The main slide- 
valve S has five openings, e and e^^ the igniting ports containing 
the two gas jets for lighting the mixture at each end of the 
cylinder ; g and g^^ the admission ports which receive the mix- 
ture of gas and air from the tube a, through the openings in the 
auxiliary slide S^ ; and h the exhaust valve, discharging through 
K into the atmosphere. In the second and smaller slide valve, Sj, 
there are only two ports for opening communication between the 
main slide valve and the gas reservoir 0. By the action of this 
slide valve the sudden admission and cut off of the slide are 
* SchOttler, Dit Gaa Moichine, p. 23. 



HISTORY OF THB GAS ENGINE. 



37 



obtained, which form a principal feature of the Hugon engine. 
The valve is driven by the same valve-rod as the valve S, 
through a pin working in a slot ; /and /, are permanent gas jets 
to rekindle the flame at e and e^, when blown out, as it is each 
time, by the force of the explosion. There are two main ports, 
serving alternately for admitting the charge to the cylinder 
and igniting it, and for discharging the gases of combustion into 
the exhaust ; this arrangement has since been altered 




C GasReMTve 



Hngon Gas Engine— Vertical. 



The action of the engine is as follows : — When the piston is 
at the top of its stroke and begins to descend, the principal slide 
valve S is driven down, and the port g comes immediately 
opposite the upper main cylinder port, forming a connection 
between it and a port in the outer slide valve S^, admitting gas 
and air from C through a. At this part of the stroke, the position 
of the slide valves is the following : — The light at e is in process 
of kindling by/ g\% opening on to the main port, while at the 
bottom of the piston the products of the last explosion are dis- 



38 GAS BNGINES. 

charging through h into the exhaust. The port g being much 
Bmaller than the main port, the supply of gas and air through Sj 
is soon cut off, but the communication of g with the main port 
is still open when the slide is suddenly driven down by the 
movement of the eccentric on the shaft. The gas flame e is 
brought opposite the inflammable mixture, and spreads through 
it, and back into the admission port. Explosion takes place 
when the piston has passed through about four-tenths of the 
stroke, and drives it down through the remainder. The piston 
and slide valve now begin to rise, and the same process is 
repeated at the lower end of the piston and cylinder. As, how- 
ever, the valve in its upward progress must again cross the 
admission passages in slide S^ before reaching the top of the 
cylinder, gas and air would be admitted at the wrong moment, 
and the rapid admission and cut off could not be obtained unless 
this valve were closed. It is driven down by the pin projecting 
from the main valve, which catches and carries it in the same 
direction. A spring then holds it in position, and does not . 
release it until the slide S has begun to return. 

The main ports, the clearance spaces at either end of the 
cylinder, and the small admission ports make up together a space 
in which about 30 per cent, of the total charge remains after 
combustion, instead of being discharged by the piston during 
exhaust. At the moment of ignition, this percentage of burnt 
products is much weaker than the fresh explosive mixture of gas 
and air. The incoming charge, cut off almost immediately by 
the down stroke of the piston, and brought directly after into 
contact with the flame, is easily and instantaneously flred. 
Explosion is far more rapid than in the Lenoir engine, and a 
longer time is afforded for expansion, and for the dilution of the 
fresh charge with the products of combustion. The explosive 
action being much surer, weaker mixtures can be employed, and 
in some of the experiments the proportion of gas to air was as 
low as 1 to 13*5. 

The speed in the Hugon engine was regulated, as in the 
Lenoir, by a governor acting on the gas valve, and the admission 
of gas was entirely suppressed, when the velocity exceeded cer- 
tain limits. The engine was lubricated in a similar way to a 
steam engine, but there was not the same necessity as in the 
Lenoir for a continual use of oil, because the water injected into 
the cylinder partly supplied its place. The motor was easily 
started by lighting the external and internal gas flames, and 
giving a few turns to the flywheel. 

In 1866 and 1867 Tresca made two experiments in France 
on a 2 H.F. Hugon engine. In the first the speed was 53 
revolutions, and the maximum pressure in the cylinder 3*27 
atmospheres. The temperature of the discharged gases was 
186*" 0., and the gas consumption 92 cubic feet of Paris gas per 



HISTOBY OF THE QAB BNGIKB. 39 

H.P. per hour. In the second experiment the highest mean 
pressure was about 3-8 atmospheres, the temperature of the 
exhaust gases 190" C. The gas consumption was about 77 cubic 
feet per H.P. per hour, not including that used for the ignition 
flame. In an experiment made by Mr. Clerk on a ^ n.F. engine. 




Fig. 7.— Hugon Engine — Indicator Diagram. 

the maximum pressure was 25 lbs. per square inch, and the speed 
75 revolutions per minute. Fig. 7 gives an indicator diagram 
of this trial. 

Siemens. — About this time the subject of heat motors engaged 
the attention of Sir William, then Dr., Siemens, and he took out 
several patents for gas and hot air engines. His regenerative 
engine will be described in Fart II. Although continually 
working on this subject, he does not appear to have constructed 
any engines, being so much occupied with other matters. 

A few years later, a gas engine was brought out by Messrs. 
Kinder & Kinsey, closely resembling the Lenoir, but presenting 
no new features. The consumption of gas was said to be about 
70*5 cubic feet per H.F. per hour. 

The defect of both the Hugon and Lenoir engines was the 
large consumption of gas in proportion to work done. This 
extravagance checked the sale of these engines, and they ceased 
to be extensively made, even before others had been invented to 
take their place. Their failure was attributed to want of 
stratification. The gases were supposed not to be properly 
mixed, and it was hoped, by altering the arrangement of the 
valves through which they entered the cylinder, to remedy the 
defect. Inventors long thought it possible to distribute the 
admission of the charge in such a way, that the gas and air were 
introduced either in separate layers or thoroughly mixed. Both 
Lenoir and Hugon were of opinion that the shock given by the 
explosion was too violent, and needed to be weakened. These 
erroneous notions were gradually abandoned, and the real 
reasons of the want of economy were at last perceived, namely, 
insufficient expansion, and the absence of compression. 

Schmidt — Million. — In 1861 Gustavo Schmidt, in a paper 
submitted to the Institution of German Engineers,* declared that 
more favourable results would be obtained, greater expansion, 

* ZeiUchri/t des Vereines deuUcher InffinUure, 1861, p. 217. 



40 GAS ENGINES. 

and better transformation of the heat of combustion into work, 
if the gas and air were previously compressed to two or three 
atmospheres. In the same year Million either re-discovered or 
was the first to apply practically Lebon's and Bamett's idea of 
previous compression of the gas and air. He took out an English 
patent, in which he proposed, like Barnett, to compress the 
mixture before admission by a separate pump, using the first 
part of the forward stroke to draw it into the cylinder. This 
idea he afterwards abandoned in favour of introducing the com- 
pressed gas and air, at the dead point, into a space at the working 
end of the cylinder, called a cartridge. Ignition followed, 
and the whole forward stroke of the motor piston was utilised 
in expansion. Million's proposals helped to develop the theory 
of the gas engine, but he does not seem to have put them into 
practice. 

Thus the principle of compressing the charge of gas and air in 
an engine before ignition had already been foreshadowed, when 
a very remarkable descriptive patent upon the subject appeared 
in France in 1862 by M. Beau de Rochas. Hitherto the con- 
struction of gas engines had not been designed and worked out 
on a scientific basis. Inventors did not fully understand the effect 
of the different operations they proposed to carry out. They were 
ignorant of the reason why one engine gave more economical 
results than another, and what methods should be adopted to 
control the extravagant consumption of gas. They were all 
ready to recognise, without being able to remedy, the defects of 
their engines. Nor were study and perseverance wanting. 
Many of the earlier gas motors were the result of much labour 
and repeated experiments, and failed only for lack of a scientific 
comprehension of the subject. 

Beau de Bochas. — The real reasons of the uneconomical 
working in the Lenoir and other motors were want of compres- 
sion, incomplete expansion, and loss of heat through the walls. 
In both the Lenoir and Hugon engines the pressures in the 
cylinder were always low and difficult to maintain, and this 
showed that the pressure generated by the explosion alone was 
insufficient, and must be increased by previous compression of 
the charge. Time was also lost in obtaining an explosion, and 
the heat, applied too late to the gas, was speedily dissipated, 
some of it going to heat the jacket water, and some being dis- 
charged at exhaust. M. Beau de Bochas, a French engineer, 
was the first to formulate a complete theory of the cycle of 
operations which ought to be carried out in a gas engine, to 
utilise more completely the heat supplied. Four conditions 
were laid down by him as essential to efficiency. 

I. The largest cylindrical volume, with the smallest circum- 
ferential surface. 

II. Maximum speed of piston. 



HISTORY OF THE GAS ENGINE. 41 

III. Greatest possible expansion. 

lY . Highest pressure at the beginning of expansion. 

These working conditions are now generally admitted to be 
necessary, but at that time they created a revolution in the 
study of the gas engine. The first shows the reason why the 
consumption of gas was so much greater in small, as compared 
with larger engines. On this subject Mr. Dugald Olerk says, 
" As an engine increases in size, the volume of gaseous mixture 
used increases as the cube, while the surface exposed only in- 
creases as the square; so that the proportion of volume of 
gaseous mixture used to surface cooling is less, the larger the 
engine." 

In the second and third conditions increased expansion and 
speed are insisted on. It was already known, or at least sur- 
mised, that unless the gases were as completely and quickly 
expanded as possible, much of the energy generated in the 
explosion was wasted. Only a small proportion was expended 
on the piston in doing work, and the gases escaped at too high 
a pressure. It was evident also, since a small cylinder wall 
surface was desirable, that the more rapidly the piston per- 
formed its stroke, the less time were the hot gases exposed to 
the action of this surface. << Other things being equal," says 
Beau de Rochas, " the slower the speed, the greater the cooling." 
Moreover the higher the speed of the piston, the more rapid and 
therefore the more perfect will be the expansion. 

In Beau de Rochas* fourth condition a principle was embodied 
which contains the essence of the question, and the true secret 
of economy in a gas engine. The utilisation of the elastic force 
of the gases by prolonged expansion depended upon the high 
pressure of the charge, and this pressure could not be realised 
unless the gas and air were compressed previous to ignition. 
Gompression was to be effected while the gases were cold, and 
the heat thus applied prolonged the expansion by increasing 
their pressure. By thus compressing the particles, an originally 
larger volume of the charge, containing more gas, can be intro- 
duced per stroke into the cylinder, and the pressure of explosion 
thus considerably raised. The advantages of compression are 
shown by the fact that the greater the pressure, and the more 
instantaneous the admission, the greater the economy. 

Beau de Boohas' Gycle. — To obtain these results Beau de 
Rochas considered it necessary to use one cylinder only, first, 
that it might be as large as possible, and secondly, to reduce the 
piston friction. In this cylinder the following cycle was to be 
carried out in four consecutive piston strokes : — 

I. Drawing in the charge of gas and air. 

II. Oon^pression of the gas and air. 

III. Ignition at the dead point, with subsequent explosion and 
expansion. 



42 GAS ENGINES. 

lY. Discharge of the products of combustion from the cylinder. 

By the addition of the important principle of ignition at the 
dead point, the crank obtained the benefit of the impulse com- 
municated by explosion and expansion during the whole of a 
forward stroke. This was not, however, the object specially 
aimed at by Beau de Kochas. He proposed to compress the 
gases to such an extent, that they ignited spontaneously at the 
dead point The principle has since been adhered to in almost 
all modem gas engines, though it has generally been found 
impossible to obtain ignition of the gases by compression only. 
Each of the four operations generally requires one stroke of 
the piston, though in some cases compression is obtained by a 
separate pump. 

This cycle, known as the four-cycle of Beau de Kochas^ 
is the one now chiefly used in gas motors. It differs from 
that of Camot because it is not a perfect or theoretical, but a 
practical, cycle. Many improvements have been effected in the 
mechanism of the gas motor, but they have all been founded on 
the sequence of operations and the working conditions described 
by Beau de Kochas. Kext to compression, the most valuable 
innovations introduced by him were, carrying out all the opera- 
tions in a single motor cylinder, and ignition at the dead point 
But like many other scientific innovators. Beau de Eochas was 
in advance of his time. Fifteen years elapsed before what 
Pi*ofessor Witz aptly calls "the programme traced of what 
ought to be attempted ** was actually adopted, although now, 
thirty years after, its merit is universally recognised, and his 
cycle employed. 

An award of 3,000 francs was presented to the veteran 
worker by the Soci^t^ d'Encouragement pour Tlndu^trie Nationale 
in recognition of his valuable labours to advance the knowledge 
of the gas engine, and one of 2,000 francs by the Acad^mie des 
Sciences. The " Soci^t^ des Amis des Sciences " also assigned 
him a pension of 500 francs. M. Beau de Bochas died in 1892. 

A translation of that part of his patent which relates to gas 
engine cycles will be found in the Appendix. 



HI8T0BY or THE GAB SNGINK. 43 



CHAPTER V. 
HISTORY OF THE GAS ENGINE-((7on/tn«^. 

CovTRNTS.— The Otto and Langen Engine— Engines byOilles, Hallewell, 
Brayton, and Simon— Ravers Rotatory Engine — Ravel's Oscillating 
Engine — ^Fonlis's Horizontal Engine. 

The construction of gas engines was meanwhile developed in a 
different direction to that indicated by Beau de Eochas. As it 
was seen that the expansion in the engines hitherto made was 
insufficient, an attempt was made to improve it by employing a 
free piston, giving in theory unlimited expansion. At the Paris 
Exhibition of 1867 the attention of scientific men was drawn 
to an engine patented by MM. Otto and Langen in 1866, and 
apparently of a new type, though it was really constructed on the 
same lines as that of Barsanti and Matteucci. It seems doubtful 
whether this new engine was more or less copied from the 
Italian's atmospheric motor, or whether the Germans worked 
independently. In any case they succeeded in making a practical 
engine, based on a principle which, owing to some mechanical 
defect in working it out, had been relinquished. 

Otto and Iiangen. — In their main features the two engines 
were identical. At that time the idea was prevalent that the 
fidlure of the Lenoir and Hugon engines was due to the slow 
movement of the piston after ignition. Scientific men were 
agreed that the energy generated by explosion was rapidly 
diminished by the cooling action of the walls; if therefore 
expansion was retarded, much of the force obtained was dis- 
sipated. In an earlier patent taken out in 1863, the inventors 
of the Otto and Langen engine say — " Experience has shown 
that the interval of time which elapses between the heating 
and consequent expanding of the gases, and the subsequent 
cooling and consequent contraction, is but a very short one, 
and, therefore, in applying the expansive force of such heated 
gases as motive power, unless they are allowed to expand 
very rapidly — immediately after combustion has taken place — a 
great portion of the heat which should have produced such 
expansion will be absorbed by the cylinder of the engine, and 
consequently a great portion of the motive power will be lost." 
Hence, the principle of their engine was to obtain the most rapid 
and complete expansion possible after explosion. Theoretically 
this idea was right, but the mechanical difficulties of working it 
out have never been completely overcome, and though the 



44 



GAS ENGINES. 



construction of the engine was continued for some years, it was 
eventually given up. 

At the time of its first appearance, the Otto and Langen was 
the most economical engine till then introduced Its consump- 
tion of gas, always comparatively low, was ultimately reduced to 
about 26 cubic feet per H.P. per hour, a quantity not greatly in 
excess of good modem gas engines. About 5,000 motors were 
constructed in ten years, and though never popular in France, 
the engine was at one time in great demand in England and 
Germany. As a practical working motor it was not satisfactory, 

but it marked an epoch 
as the first single-acting 
engine, and the first in 
which economy in con- 
sumption of gas was 
realised as a conse- 
quence of better ex- 
pansion. It was, how- 
ever, large for the power 
generated, noisy and 
irregular in action, and 
the very rapid ascent 
of the piston caused so 
much vibration, that it 
could only be used for 
small powers. 

Otto and Iiangen, 
two Pistonfl.— In the 
patent taken out by 
Otto and Langen in 
1863 the principles they 
intended to work upon 
were set forth. They 
proposed to construct 
an engine with a verti- 
cal cylinder open at 
the top, containing two 
pistons and piston-rods, 
one above the other. 
By having two pistons 
it was intended to break 
the force of the explo- 
sions, for the idea had not yet been abandoned that the shock was 
injurious to the efficiency of the engine. The two pistons being 
at the bottom of the cylinder, the momentum of the flywheel raised 
the upper piston and rod, which were hollow. The force of 
the explosion then drove up the lower solid piston through the 
other, the air in the cylinder being forced out through valves at 




Fig, 8.— Otto and Langen Vertical Engine — 
Transverse Section. 



HISTORY OF THB GAS ENGINE. 45 

the top of the hollow piston ; both pistons descended together 
in the vacuum formed below them. This design presented 
various difficulties, and the inventors soon relinquished it^ and 
exhibited for the first time at the Paris Exhibition of 1867 their 
well-known atmospheric engine. 

Otto and Langen, Single-Piston Atmospheric Engine. — 
Fig. 8 gives a sectional elevation of this engine. A is the long 
vertical cylinder, surrounded at the bottom with a water jacket 
and open at the top to the atmosphere. P, the piston, is shown 
almost at the end of the down stroke. C is the rack in lieu of a 
piston-rod, gearing into the toothed wheel T on the main 
shaft K. The slide valve S, worked by an eccentric, O, admits 
the gas and air, which are ignited by a flame in the slide valve 
cover, and also discharges the products into the exhaust pipe. 
There are two eccentrics side by side, O and B ; both are con- 
nected to the auxiliary shaft M during the down stroke, but 
run loose on the up stroke of the piston. In the same way the 
wheel T, which is also free of the shaft during the up stroke, 
becomes wedged to it by an ingenious clutch arrangement as 
the piston descends. The action of the Otto and Langen engine 
necessitates the use of three special mechanisms, the friction 
coupling or clutch gear, on the outer wheel T of the main shaft, 
the device for lifting the piston to admit a fresh charge, served 
by eccentric B, and the valve motion driven by eccentric O. 

The violence of the explosion in a free piston engine is so great, 
that much care is necessary to make the clutch act freely and 
instantaneously. At the moment when the movement of the 
piston is reversed, the whole energy of the engine being stored 
up in it, the least recoil might result in an accident. This was 
one reason why the Barsanti and Matteucci engine failed ; the 
ratchet and pawl were not sufficiently prompt in action. The 
clutch gear of the Otto and Langen engine, shown at Fig. 9, was 
the result of careful study, and formed one of the most ingenious 
parts of the engine. Upon the main shaft K there is a circular 
disc, a, which is solidly keyed to it, and carries on its outer edge 
at e four steel wedge-shaped slips or projections. The inner rim 
of the outer toothed wheel T is hollowed out in four places at 
regular intervals, just below the bolts d, and corresponding to 
the steel wedges e upon the disc a. In each of the grooves thus 
formed are three small cylindrical rollers. The main shaft K 
revolves always in the direction of the hands of a clock. When 
the piston flies up with the force of the explosion, and drives 
round the toothed wheel T in the opposite direction, the rollers 
run loose in the open space in the wider part of the hollows, and 
no pressure being exerted on the wedges a, the connection be- 
tween the main shaft K and the rack, piston, and outer toothed 
wheel T is severed. The piston having reached the end of the 
up stroke, begins rapidly to descend (motor stroke), the motion 



46 



GAS ENGINES. 



of T is reversed, and it also revolves in the same direction as the 
motor shaft. The rollers are driven forward into the narrowest 
part of the space, and wedged against the steel slips e, which grip 
the solid disc a, and the whole mass from T to K is driven round 
in the direction of the descending piston. The cooling of the 
gases helow the piston forms a vacuum, but this is counteracted 
near the end of the stroke by the opening of the exhaust. Slight 
compression of the gases of combustion takes place at the bottom 
of the cylinder, and the motion of the piston is slackened. The 
toothed wheel T, therefore, revolves more slowly than the main 
shaft and disc a ; the rollers run back, and loosen their grip of 
the wedges, and before the piston has reached the end of the 
stroke, the motor shaflb is again disconnected. 

The working of the eccentrics diiving the slide valve S is also 
shown at Fig. 9. The valve is somewhat similar in principle to 







Fig. 9. — Otto and Langcn Engine. 

Hugon's flame ignition valve, but more simple, as only one igni- 
tion per up stroke or per revolution is required. There is one 
main port, % Fig. 8, leading to the cylinder, and just above it 
are two small openings, h and J, for admitting the gas and air. 
In its lowest position the slide valve port forms a communication 
between % and the atmosphere, the exhaust outlet in the valve 
cover being closed by a flap valve, which is lifted only when the 
pressure in the cylinder is greater than the atmosphere — that is, 
when the piston has nearly reached the bottom of its stroke. 
The products of combustion being thus discharged, the slide 
S worked by the eccentric O begins to rise, and the piston with 
it, lifted by the other eccentric B; gas and air enter through 7, A, 
in the proportions of 9 to 1, mix and pass through to the cavity 
m. Communication is now made between m and the outer per- 



HISTORY OF THB 0A8 ENGINE. 



47 



fuanent flame ^ and the mixture of gas and air is ignited. The 
upward progress of the valve shuts off the flame at /, and the 
burning gases being brought opposite the main port t rush into 
the cylinder, explode, and drive up the piston. 

The movement of the two eccentrics O and B is given by 
the auxiliary shaft M, on which is fixed a ratchet wheel, W. 
The eccentrics are set to each other at an angle of 90*", and 
run loose on the shaft, except at certain times. Eccentric O 
^^irries the rod working the slide valve S, B has a bell crank, r, 
working on a pivot, and a lever, N. Another lever, L, has 
a projection, u, which, during the greater part of the stroke, 
presses against r and pushes it up, so that it does not catch 
in the ratchet wheel W of the shaft M. During the down- 
stroke of the piston a projection, 8, upon the rack 0, strikes 
the lever L and holds it down, r is released and catching into 
the ratchet wheel on the shaft M causes the two eccentrics 
to be carried round with it. The slide valve has been stationary 
during this time, with the exhaust port open to the cylinder. 
The flap on the slide cover which usually closes it has been lifted 
by the pressure of the gases, and they are discharged during the 
down stroke. Meanwliile the piston having reached the bottom 
-of the stroke comes to a stand, because the rack is no longer 




Fig. 9ck — Otto and Langen Engine— Plan. 

geared to the wheel T. The lever N on the other eccentric B, 
after revolving with the shaft M, is brought round, and catching 
under the projection 8 on the rack, lifts it and the piston. The 
slide valve raised by eccentric O admits and ignites a fresh 
charge. The up stroke releases the lever L from 8, the pro- 
jection u pushing against r once more disengages it from the 
shaft M, and the two eccentrics, being no longer connected to it, 
are brought to a stand. Fig. 9a shows a plan of the engine. 



48 GAS ENGINES. 

This description will explain the method of ignition adopted 
in the Otto and Langen engine. The gases being ignited at 
low pressure, the ignition by flame, as in all non-compressing 
engines, worked satisfactorily. The speed was regulated by a 
ball governor, not shown in the drawing. If the speed of the 
engine exceeded the proper limits, the governor, by means of a 
pawl and ratchet, disconnected the levers working the slide valve 
and piston, and no charge was admitted until the speed was 
reduced. Thus the number of explosion strokes, instead of the 
strength of the charge, was diminished. This method worked 
more economically than direct action of the governor upon the 
gas admission. It was found that to reduce the proportion of 
gas impoverished the mixture, the explosion sometimes missed 
fire, and a certain quantity of unburnt gas passed through the 
cylinder. A third method of checking the speed was to connect 
the governor with the opening for the exhaust. By reducing 
its section, the counter pressure of the gases in the cylinder 
checked the down stroke of the piston, and therefore diminished 
the number of strokes per minute. 

As the engine was single-acting, working open to the atmo- 
sphere, the heat generated was not so great as in the earlier 
motors. The number of strokes per minute being relatively 
small, the cylinder was kept comparatively cooL It was not 
difficult to start the engine, a few turns of the flywheel being 
sufficient to draw in the charge, and cause it to ignite. 

A peculiarity of the Otto and Langen engine is that the 
number of piston strokes and revolutions of the crank are 
independent of each other. In an experiment on an engine of 
this type by Meidinger, the number of revolutions of the crank 
shaft varied from 40 to 106, and the strokes per minute from 
20 to 43. At full power Mr. Clerk reckons the normal number 
of piston strokes at 30, and of revolutions at 90 per minute. 

Another curious feature in this engine is that the action of 
the walls, which has so injurious an effect in most engines, by 
carrying off the heat, is here of positive use. During the up 
stroke, the walls, by rapidly cooling the expanding gases, assist 
in forming the vacuum, while in the down stroke they carry off 
the heat, and retard the increase of pressure below the piston. 

A number of experiments have been made upon the Otto and 
Langen engine. Of these the best known is Tresca's trial at 
the Paris Exhibition, 1867, on a half H.F. engine, lasting half 
an hour. The number of revolutions per minute was 81 ; the 
consumption' of Paris gas, not including that used for the burner, 
was 44 cubic feet per I.H.F. per hour. Tresca estimates that 
only about 17 per cent of the total heat was carried off in the 
cooling water. Another series of experiments, extending over 
several weeks, was made in 1868 by Meidinger on an engine of 
the same size. It ran at 75 revolutions per minute, a speed. 



BISTORT OF THE GAS ENGINE. 



49 



which Meidinger found to give the best results. The gas con- 
sumption per H. P. per hour varied from 49 to 29 cubic feet ; 
the temperature of the exhaust gases was found to decrease with 
the number of piston strokes per minute. In these trials an 
experiment was made, by allowing the governor to act sometimes' 
upon the gas admission, sometimes upon the exhaust valve. In 
both cases the amount of work performed, and the number of 
revolutions was the same ; but when the gas supply was cut off 
by the governor, the piston made twice as many and much 
shorter strokes, and the gas consumption was two-sevenths more. 
Meidinger also utilised these experiments to test the value of 
ignition at the dead point, and found that it not only prevented 
shock to the engine, and increased the number of expansions, but 
also augmented the speed. In an atmospheric engine this 
increase of speed was valuable, because it principally affected 



J^Tssun Ibr^ptr Sf inc^ 




Fig. 10. — Otto and Langen Engine — Indicator Diagram (Clerk). 

the speed of the up stroke, and hence gave a more rapid expan- 
sion. Mr. D. Clerk also made experiments upon a 2 H.P. Otto 
and Langen engine, the diagram of which is given in Fig. 10. 
The consumption of Oldham gas was at the rate of 36 cubic feet 
per brake H.P., and 24*6 cubic feet per I. H.P. per hour. There 
were 28 ignitions per minute. 

The great defect of the Otto and Langen engine was its noisy 
and unsteady action, due to the rack and wheel, and the exces- 
sive vibration and recoil. Several efforts were made in the 
course of the next few years to improve upon it, though the 
working principle remained the same. 

Qilles. — In 1874 an engine was brought out at Cologne by 
Gilles, the chief novelty of which was the introduction of two 
pistons, to avoid the noise and recoil of the Otto and Langen 
motor. The pistons worked vertically one above the other in 
the same cylinder, closed at the top, and open at the bottom 
to the atmosphere; the lower was the motor, and the upper 
the free piston. At starting, the two pistons were together in 
the middle of the cylinder. By the energy of the flywheel, the 

4 



^0 GAS ENGINES. 

motor piston being at its upper dead point was driven down, 
uncovered the port for admission of gas and air at the side, and 
the charge entered between tho two pistons. The free piston 
was also forced down by air admitted through a valve at the top 
of the cylinder, until it was checked. The slide valve, through 
which the charge had entered, was next raised by a cam worked 
from the main shaft, cut otf the admission, and brought the 
mixture opposite an external firing flame. Explosion followed, 
and the force drove up the free piston to its full height, the air 
above it escaping through holes in the cylinder cover. Mean- 
while the lower or working piston was forced down through its 
lowest point, and driven up by the pressure of the atmosphere 
into the vacuum formed between the two pistons by the cooling 
of the gases. The upper free piston having reached its highest 
position, it was arrested, and not allowed to descend, till a 
second cam on the main shaft moved a lever, and set it free. 
The products of combustion between the pistons were driven out 
through a discharge port in the centre of the cylinder. 

The Gilles engine was constructed by the Arm of Humboldt 
k Cie., at Kalk, near Cologne, and in England by Messrs. Simon, 
of Nottingham, who exhibited it at the Paris Exhibition in 1878. 
The catch arrangement for arresting the upper piston was always 
a weak point, but before improvements for remedying this and 
other defects had been introduced, the engine was superseded by 
the Otto. Two drawings of it will be found in Schottler. 

An extremely useful little engine was introduced by Alexis 
de Bisschop, and also exhibited at Paris in 1878. Patents dated 
1870, 1872, 1874. It resembles an atmospheric engine in prin- 
ciple, but the piston is not free; this engine will be found 
described in the modem part of this work. 

Hallewell. — In England a patent for a kind of vertical 
double-acting atmospheric engine was taken out by Hallewell 
in August, 1875. Like Gilles, Hallewell aimed at overcoming 
the defects of the Otto and Langen engine, and this he pro- 
posed to do by the use of two cylinders, one single- and the 
other double-acting. A lever raised the piston of the first single- 
acting cylinder to admit a charge ; explosion followed, and the 
piston was driven freely up to the to[) of the cylinder, where a 
discharge valve opened. It then descended in the vacuum 
formed below it by the cooling of the gases, and communication 
was opened between the vacuum and the valve-box of the second 
double-acting cylinder. In this cylinder air was admitted alter- 
nately on either fisice of the piston, through a rotating slide valve, 
and with the help of the vacuum in the first cylinder, the piston 
was driven to and fro by atmospheric pressure. The idea was 
ingenious but complicated, and the engine had little success. 

MM. Otto and Langen had by this time formed their busi- 
ness into a company at Deutz, near Cologne, and the firm was 



HI8T0BY OF THE GAS EKQINB. 51 

henceforth known as the " Deutzer Gas-Motoren Fabrik." They 
had been working incessantly to improve their engine, but alter 
introducing several modifications, they finally abandoned alto- 
gether the idea of a free piston. At the Paris Exhibition of 
1878 they brought out the celebrated Otto engine, described 
in Ohapter vii., which rapidly superseded all others, and created 
a revolution in the construction of gas engines. At the same 
Exhibition two other engines made their appearance which, 
although neither of them permanently successful, presented 
several novel and interesting features. 

Brayton. — This American gas engine had already been in- 
troduced by Brayton at Philadelphia in 1873. Owing to the 
peculiar method of igniting the gases, difficulties were soon 
experienced, which induced the inventor to substitute petro- 
leum for gas. A full description of his later engine will be 
found in Part II., Petroleum Motors. In 1878 Messrs. Simon, 
of Nottingham, obtained Bray ton's gas engine patent, and brought 
out the motor in England. As in the Otto, the charge was 
compressed, but otherwise this engine differed from all earlier 
types, and illustrated the principle of ignition at constant pres- 
sure, instead of at constant volume. After compression in a 
separate pump, the gas and air were delivered into the motor 
cylinder, but they were not admitted cold and then ignited and 
exploded, according to the usual cycle of operations. A small 
flame in direct communication with the cylinder was kept con- 
stantly alight, and kindled the gases as they passed it. Thus 
they were gradually ignited, and entering as flame, drove the 
piston forward, not by the pressure of explosion, but of combus- 
tion. The heat was imparted to the gas at constant pressure — 
that is, the piston moved as soon as the flames began to enter 
the cylinder, but there was no sudden explosion. A wire gauze 
was fixed behind the light, to prevent the flame from striking 
back into the compression cylinder. This method of ignition 
worked well as long as the wire gauze remained intact, but it was 
liable to bum into holes, and if the gases found their way back 
through any aperture, an explosion followed, and the light was 
extinguished. On this account Brayton abandoned the use of 
gas in his engine, and substituted petroleum vapour. 

Simon. — To this gas engine Messrs. Simon added a small 
boiler above the cylinder, the water in which was evaporated by 
the heat from the exhaust gases. The engine was vertical and 
single-acting. The steam injected into the motor cylinder in- 
creased the expansive force of the gases, and helped to lubricate 
the piston. This idea was not a novelty. It had been tried by 
Hugon, but neither his engine nor the Simon was practically 
improved by it. The increased bulk added to the cost of 
construction, and the steam was found to have an injurious 
effect, and to cool the contents of the cylinder too much. On 



52 



OA8 ENGINES. 



tive/ 



this point Professor Schottler pertinently asks — "Whether 
it can be considered an advantage, since the gas engine is 
expressly designed to avoid the defects and dangers of a 
steam boiler, to add the latter to iti For small motors at 
least, the question must decidedly be answered in the nega- 
♦:«^»» Although the theoretical principle of the Simon 

engine was excel- 
lent, it did not 
succeed. It was 
first shown, like 
the Brayton, at 
the Paris Exhibi- 
tion of 1878. 

Fig. 11 gives a 
section of the en- 
gine ; a descrip- 
tion will explain 
the method of 
working. A is 
the motor, B the 
pump cylinder, 
and K the crank 
shaft. Gas and 
air are admitted 
by the slide valve 
Sj at the top of 
the pump cylin- 
der, and drawn in 
through the valve 
a at the down 
stroke of the pis- 
ton ; the up stroke 
compresses and 
drives them 
PVyx^^^v>^<?VX>'^^-/ >>^ -yyyy^y^y^^'^yy^ through another 
Fig. 11.— Simon Vertical EDgine. valve b into the 

receiver c. From 
here they pass into the motor cylinder A, through the slide 
valve S ; J is a gas jet burning continually in front of a wire 
gauze, at which the gases are ignited in their passage, and by 
their expansion drive down the piston P. The exhaust is 
worked by the slide valve d, driven from the main shaft. The 
products of combustion are led through the coiled tubes e in the 
small boiler F, before discharging into the atmosphere. As soon 
as some of the water in the boiler is evaporated by the heat of 
the exhaust gases, the steam passes through the pipe / and slide 
valve S into the motor cylinder. A small cam, A, on the governor 
G acts upon the slide valve S^ for admitting the gas and air, and 





HI8T0BT OF THB OA8 BNGINB. 53 

cuts off the admission entirely, as soon as the speed of the engine 
becomes too great ; this is shown in Fig. 11. 

Several experiments have been made upon the Brayton and 
Simon engines. In 1873 Professor Thurston tested a Brayton 
engine in America, of 5 nominal H.P., and found that the 
maximum pressure in the cylinder was about 75 lbs. per square 
inch at the beginning of the stroke, decreasing to 66 lbs. at 
the out off. The H.P. indi- 
cated 8-62, brake power 3*98, 
and consumption of gas 32 
cubic feet per I. H.P. per hour. 
According to Mr. Clerk the 
power used for driving the Pig. 12. -Brayton Gaa Engine— 

Eump, which causes the actual Indicator Diagram, 

orse-power to be less than half 
the indicated, ought not to be included in estimating the con- 
sumption of gas. Deducting this, he calculates the expenditure 
at 55*2 cubic feet per H.P. per hour. Another experiment made 
by Mr. M'Mutrie, of Boston, showed a maximum pressure in the 
cylinder of 68 lbs. per square inch, the piston speed was 180 feet 
per minute, and the total power developed 9 H.P., the friction 
and other resistance amounting to nearly 5 H.P. Fig. 12 shows 

the diagram of this ^.^^^ 

trial. In an expert- ^ 7^^^'*"--........,^^^ 

ment made upon a | / *"\^^ 

Simon engine of 7*7 "5 / ^^v^ 

LH.P., 2 H.P. were :! I ^V,^^^^^ 

required for the pump, ^ V ^^—^...nimoMpk 

and the total gas con- pj^ 13. -Simon Engine— Indicator Diagram, 
sumption was 50 cubic 

feet per brake H.P. per hour. The diagram of a Simon engine 
at Fig. 13 was taken by Dr. Slaby. 

The engine was brought out in Germany by the firm of Otto 
Hennig & Oie. of Berlin, by whom several improvements were 
introduced, patented by Hambruch. As in the original engine 
the flame was sometimes blown out by the pressure of the gas, it 
was protected by a small cap and cover, and the burner made in 
the shape of a cock, with a handle to lift it out and relight it, if 
extinguished. In the larger engines, the ignition flame was fed 
from a separate small gas pump. Another improvement was to 
replace the exhaust and admission slide valves of the Simon 
engine by lift valves. The admission valve was opened by a 
tappet working in a socket on the main crank shaft. If the 
speed was too great, the governor at the end of the crank shait 
drew the socket to one side, and the tappet missed it partially 
or altogether. Air entered the admission valve from below, gas 
was admitted through small holes in the seat of the valve, as in 
the Clerk engine, and a thorough mixing of the two was thus 



54 OAS BNQINBS. 

attained. There was also an ingenious arrangement for equalise 
ing the pressure in the pump and motor cylinders. The admis- 
sion valve, being very heavy, did not lift until the pump piston 
was halfway through the up stroke. A small piston above it 
worked in a pipe connected to the motor cylinder, and a hole in 
thi motor piston fitted over the opening of the pipe during the 
down stroke. As soon as communication was established, and 
the pressure in the two cylinders equalised, the admission valve 
fell back upon its seat, and remained closed until the next up 
stroke. 

Bavel Botatory Eng^e. — Another interesting engine, two 
varieties of which were shown at the Paris Exhibition of 
1878, was the French "Moteur Ravel." The first type was 
double-acting and rotatory, and was called by the inventor " an 
engine with variable centre of gravity." The cylinder turned 
upon a transverse axis, and had two heavy pistons joined to- 
gether by a bar of iron, without piston-rod or connecting-rod. 
Gas and air were first admitted and compressed in two small 
pumps worked from the crank shaft, and the charge introduced 
alternately at either end — that is, at the top and bottom of the 
motor cylinder, as long as it retained a vertical position. By 
the explosion at the bottom of the cylinder both pistons were 
forced up together to the top, to be driven down again by the 
explosion of the compressed charge from the other pump 
cylinder. The motor pistons being very heavy, their motion 
altered the centre of gravity, and caused the cylinder, while 
oscillating, to turn round on its axis. The crank shaft in the 
centre was made to rotate by the movement of the pistons and 
cylinder, the piston speed being independent of the number of 
revolutions. The extreme delicacy of adjustment required in 
this engine caused it to be superseded by others; the con- 
sumption of gas was said to be about 35 cubic feet per H.P. 
per hour. Two drawings of the Ravel rotatory motor will be 
found in Se?idttlery p. 36. 

Bavel Osoillating Engine. — Another vertical oscillating 
single-acting type of the same engine was brought out by 
M. Ravel, and more favourably received in France. In this- 
motor the piston-rod was directly connected to the crank shaft. 
The vertical cylinder oscillated on a centre at its lowest part. 
The force of the explosion drove up the piston and crank shafts 
causing the cylinder to oscillate and the crank shaft to rotate. 
The piston descended by the impetus of the flywheel, and the 
shaft having completed its revolution, the cylinder returned to 
its original position. The action was very similar to that of an 
oscillating steam engine. Gas and air were admitted at atmo- 
spheric pressure through a slide valve, worked by a cam on the 
main shaft, oscillating with the cylinder. Ignition was effected 
by an external flame in the ordinary manner. There was no- 



BISTORT OF THE OAS ENOINB. 55 

special exhaust valve, but the exhaust port was uncovered 
periodically by the oscillation of the cylinder. Gas entered 
through a pipe in the slide valve, moving to and fro in the valve 
cover, which opened by degrees to admit an increasingly rich 
charge; thus the mixture finally admitted nearest the flame 
contained most gas and was more easily ignited. The governor 
acted by throttling the supply of gas. This engine was said, 
like the last^ to consume 35 cubic feet of gas per H.F. per hour, 
but it is doubtful whether so low a consumption could be 
obtained in a gas engine working without compression. 

FoiiliB. — The horizontal engine patented by Foulis of Glasgow 
in 1878, an improved type of which was brought out in 1881, 
resembled the Simon in principle, and contained a motor cylinder 
and pump. The object aimed at by the inventor was to cause 
combustion to take place in the motor cylinder, at about the same 
pressure as that in the pump. This was obtained by adjusting 
the angle of the crank-pin working the pump, and proportioning 
the dimensions of the latter to those of the motor cylinder. In 
theory the engine was excellent. The hot gases, after being 
compressed in a pump, were forced through layers of wire gauze 
and an annular orifice into the combustion chamber, lined with 
non-conducting material, and kept at a red heat which sufficed 
to ignite the charge. From here they passed at constant pres- 
sure and in a state of flame into the motor cylinder. Admission 
was cut ofi* at one-third of the stroke. Before being allowed to 
escape, the gases of combustion were made to circulate round 
tubes of fire-clay behind the combustion chamber, which were 
intended to act as a regenerator. The fresh charge passed 
through them immediately after, and some of the heat of the 
exhaust gases was thus utilised, but these and other details 
presented so many difficulties that the construction of the 
engine was afterwards given up. To raise the temperature of 
the incoming charge in a gas engine by means of the exhaust 
heat is an important problem, which inventors have hitherto 
been unable to solve successfully. 



CHAPTER VI. 
HISTOBY OP THE GAS BNGHNB— (Con^tnt^cQ. 

Contents. — Engines — Clerk — ^Beck — Wittig and Hees — Seraine— Sturgeon 
— ^Martini — Tangyo — Victoria— Economic— Bonier and Lamart—Forest 
— Ewins and Newman— Fran^oia — Warchalowaki — No6l— Durand — 
Mire— Baldwin. 

In a history of the development of the gas engine it is important 
to study, not only modem working motors, but those engines 



56 QAS ENGINES. 

which, although no longer made, are good in design and principle, 
and, therefore, deserve attention. During the last twenty years 
many motors have been brought out, excellent in theory and 
often in workmanship, which have not permanently succeeded 
only because they were found to infringe previous patents, 
or were superseded by more practical types. As none of these 
engines date earlier than 1878, they will not be presented in 
historical sequence, but, as far as possible, in the order of their 
importance. From henceforth it will no longer be necessary 
to distinguish between single-acting and double-acting engines. 
The double-acting type of motor, in which the charge was in- 
troduced alternately at either end of the closed cylinder, was 
abandoned after the failure of the Hugon, for reasons already 
given. Since that period no engines of this kind have, to the 
author's knowledge, been constructed, with the exception of the 
modified Griffin six-cycle motor. All others are single-acting, or 
admit the charge at one end only of the cylinder. 

With the advent of the Otto gas engine, a new era began. 
Until the appearance of this motor in 1876, not one of the many 
engines produced had utilised the cycle of operations indicated, 
many years before, as the best and most economical by Beau de 
Kochas. Neither invention nor practical application was want- 
ing, and as none had proved a real success, we may at least 
assume that their failure was due partly to the neglect of this 
cycle. It is Otto's special merit that he was skilful enough to put 
the principles of the French aavarU into working operation, and 
the success of his engine proved their value. It had, however, 
defects, which in a few yeai*s began to be generally recognised. 
As in all other gas engines, expansion was not complete, and 
the gases were discharged at a relatively high temperature and 
pressure. The engine had also only one explosion and one 
motor stroke in four — that is, three strokes out of every four of 
which the cycle consisted, were spent in negative work, and 
only one in positive work. 

Clerk. — It was to remedy the second of these defects that 
Mr. Dugald Olerk applied himself, in the important engine he 
produced and first exhibited in 1880. This motor, which is 
certainly one of the best brought out in England, was made by 
Messrs. Thomson, Sterne & Co., of Glasgow. Its distinguishing 
feature was that an explosion at every revolution was obtained. 
Of the four operations of the cycle, Olerk proposed to transfer 
the first only, admission, to an auxiliary cylinder, which he called 
the displacer. The gas and air being drawn into the displacer 
were slightly compressed, and delivered into the working 
cylinder. Here they drove out before them the products of 
combustion. The motor piston in returning compressed this 
charge into a chamber at the further end of the cylinder. It 
was then fired and drove the piston forward, the displacer piston 



BISTORT OF THE QAS ENGINE. 



57 



taking in a fresh charge of gas and air. The exhaust ports were 
in the front part of the cylinder, and the piston as it moved 
out uncovered them, and acted as an exhaust valve. The dis- 
charge of the exhaust gases constitutes another fundamental 
difference between the Otto and the Olerk engines. Otto con- 
sidered that the presence of a certain quantity of unbumt gases, 
by retarding the progress of combustion, contributed to the 
efficiency of his engine. Clerk held that this residuum of 
unconsumed gas was highly injurious to the fresh chaise, 
which it diluted and rendered more difficult to ignite. He was 
of opinion that if the motor cylinder were previously cleansed, as 



oa 




Fig. 14.— Clerk Engine — Sectional Elevation. 

iar as possible, of the products of combustion, a weaker mixture 
might be used for the charge, and more perfect ignition and 
greater economy obtained. 

Figs. 14 and 15 give a sectional elevation and plan of the 
Clerk engine. A is the motor cylinder with piston P, B is the 
displacer cylinder with piston D, which is set on the crank at an 
angle of 90*" in ad-^ance of the motor piston, G is the conical 
compression space at the back of cylinder A. There are two 
automatic lift valves, shown at Fig 14, H, from which the gas 
and air pass through the pipe W (Fig. 15) into the displacer 
cylinder, and F, which is raised to admit the charge under slight 
pressure into cylinder A. Both the valves are provided with 



58 



OAS ENGINES. 



" quieting pistons/' to prevent any noise or shock. The ignition 
slide valve S has a flame o which is continually relit from the 
permanent Bunsen burner at h. Near the front of the motor 
cylinder are the two exhaust ports E^ and Eg, uncovered by the 
piston F when it reaches the end of its stroke, and from whence 
the gases of combustion pass into the discharge pipe E. 

The action of the engine is as follows : — The piston D of the 
displacer moves out, and draws in a charge of gas and air 
through H. The seat of this valve is pierced with holes to 
admit gas from the supply pipe, the forward movement of the 
displacer piston lifts the valve, the air enters from chamber It 
below, and mixes thoroughly with the gas penetrating through 
the holes. The number and size of the holes, in proportion to 
the lifting area of the valve, regulate the supply of gas, and, 
therefore, the richness of the mixture. The air valve H falls 
back on its seat by its own weight, but the gas supply is cut off 
before the piston D has quite reached the end of its stroke. The 




Fig. 15.— Clerk Engine— Sectional Plan. 

last part, therefore, of the charge in the displacer cylinder, first 
expelled as the piston begins to return, is pure air. Meanwhile 
the out stroke of the motor piston has begun, at an angle of 90* 
behind that of the displacer, and near the end of the stroke the 
exhaust ports E^ and Eg are uncovered. The pressure inside the 
motor cylinder is immediately reduced to that of the atmosphere. 
The displacer piston has already nearly completed its return stroke, 
and the slight pressure exerted on the charge is sufficient to lift 
the automatic valve F, and to admit the gas and air into the 
conical chamber G, at the end of the motor cylinder. As the 
motor piston passes over the exhaust ports, the fresh charge 
entering from the cool displacer, and immediately expanded by 
the heat of the motor cylinder, drives out the products of com- 
bustion before it. Mr. Clerk admits that a small part of the 
fresh charge escapes with them, but as, owing to the arrange- 
ment of the admission valves, this is mostly pure air, the cylinder 
is swept clean, and there is very little actual waste of unburnt 



HISTORY OF THE QAS ENGINE. 



59 



gas. The motor piston in returning first covers the exhaust 
ports, the valve F is instantly closed by a spring, and admission 
firom the pump cylinder cut off. The mixture is then compressed 
into the chamber G, while the displacer piston begins the out 
stroke, and takes in a fresh charge. 

Ignition follows by a flame iu the slide valve S. The method 
adopted, shown in Fig. 15, but more clearly in Fig. 16, differs 
from that used in engines having only one motor stroke in four, 
because an ignition is required at every stroke. With the high 
pressure of the gases, and the great number of explosions, some- 
times nearly 300 per minute, the slide would soon become red- 
hot, unless special precautions 
were taken to prevent it. The 
small combustion chamber or 
cavity 1, Fig. 16, in slide valve 
S, has two openings. On one 
side it communicates with the 
Bunsen burner b through the 
port 2, on the other by port 3 
with the outer air, or with the 
explosion port of the cylinder, 
according to the position of the 
slide. A small portion of the 
compressed mixture is ad- 
mitted from the explosion 
port 5, through an opening i, 
into a grooved hollow in the 
slide valve, and is carried 
round to the cavity or cham- 
ber 1, which it enters behind 

the flame from striking back into the hollow. At 8 is shown the 
pin in the slide regulating t^e supply of gas to the grating. At 
the moment when port 2 of the cavity is open to the Bunsen jet 
burning against the fjEtce of the valve, port 3 communicates through 
6 with the outer air. The gases ignite gradually as they enter the 
cavity through the grating, the products of combustion discharg- 
ing into the atmosphere, and the gases being fed with air through 
port 6. As the slide moves up, carrying the burning mixture, 
port 2 is closed and the flame cut off, and port 3 is brought 
opposite the cylinder explosion port. The current feeding the 
flune in the cavity is so regulated, that the pressure of the ignited 
gases is less than that in the motor cylinder ; hence the charge 
is easily fired. Explosion follows at the inner dead point, the 
piston is driven forward, the displacer takes in a fresh charge,, 
and the cycle is repeated. 

Great care has been taken in this engine to proportion the 
volume of the two cylinders, to prevent the escape of any consider- 
able part of the incoming charge with the exhaust gases. The 




Fig. 16.— Qerk Engine 
Valve. 



-Ignition 



a gratiug 7, intended to prevent 



€0 GAS ENGINES. 

volume of cylinder B is almost exactly equal to that of cylinder A, 
deducting the compression space G, and the exhaust ports covered 
by the piston. But as the gases expand in consequence of the 
slight pressure in cylinder B, and the heat of the walls in cylinder 
A, their volume is increased by one-third. The mixture origin- 
ally admitted is in the proportion of 1 part of gas to 8 of air. 
To avoid the discharge of any of the fresh gases, a small part of 
the products of combustion remains in the cylinder ; this mixes 
with the fresh charge, and is estimated by Mr. Clerk as one- 
tenth of the total volume. The composition of the actual charge 
will, therefore, be 1 of gas to 10 of air and products. 

Clerk Ctovemor. — The governor in the Clerk engine is simple. 
Between the upper and lower lifting valves for admitting the 
charge to the motor and displacer cylinders is a gridiron alida 
WhUe the engine is working under normal conditions, this is 
kept open during the charging stroke by a spring and lever, 
worked from the slide valve S ; but if the speed becomes too 
great, the balls of the governor moving out raise a lever, which 
oatches into the lever moving the gridiron valve, and lifts it. 
The valve is drawn forward and closed, and the admission of gas 
and air wholly cut ofL The two pistons continue working, but 
compress and discharge only the products of combustion, until 
the speed is reduced, and the levers lowered. This method of 
regulating by a gridiron slide was the invention of Mr. Garrett, 
of Messrs. Sterne's Works. Above each cylinder is a small oil 
reservoir, with an adjustable screw admitting so many drops per 
minute. 

For starting, a special apparatus was designed by Mr. Clerk 
in 1883. The pipe through which the gases pass from the dis- 
placer to the motor cylinder can be made to communicate with a 
small reservoir, and a supply of gas and air forced into it, while 
the engine is running. The reservoir, charged with the mixture 
compressed to 60 lbs. per square inch, is closed with a stop valve, 
and can be kept air-tight for weeks. To start the engine, the 
crank is brought round to the inner dead point, the displacer 
piston being set at a quarter of its stroke. Communication is 
then established between the two cylinders and the reservoir, 
and the burner lit. The compressed air is thus admitted to both 
cylinders, and drives back the displacer piston to take in a 
charge, and the motor to uncover the exhaust ports. It is 
usually sufficient to open the starting valve once or twice, but 
the reservoir contains enough to start the engine six times. 

Tests and experiments on the Clerk engine have been made by 
the inventor and the makers. The engines varied from 2 H.P. 
to 12 H.P., and the number of revolutions from 212 to 132. 
With the 2 H.P. engine the average pressure in the cylinder was 
43 '2 lbs. per square inch, and the consumption of gas per LH.P. 
per hour 29-8 cubic feet ; in the 4 H.P. the average pressure was 



HISTORY OF THE QAS BNOINB. 



61 



63*9 lbs. and the gas consumption 2419 cubic feet. The 6 H.P. 
engine (Diagram, Fig 17) gave an average pressure of 53*2 lbs. 
per square inch, with 24*3 cubic feet of gas consumption ; in the 
8 H.P. the pressure was 60*3 lbs. and a gas consumption of 20*94 
cubic feet, while in the larger 12 H.P. engine, the diagram of 




200Ua 



Atmaspk 
Fig. 17.— Clark 6 H.P. Engine— Indicator Diagram. 

240 Ul 
200 




Atn&fph. 



Fig. 18.— Clerk 12 H.P. Indicator Diagram. 

which is shown at Fig. 18, the gas consumption was 20*39 cubic 
feet, with an average pressure of 64*8 lbs. It will be observed 
that the consumption of gas diminishes in proportion as the size, 
power, and pressure increase. The Glasgow gas used was very 
rich, and of high heating value. 

The foregoing sketch of the Clerk engine shows that^ though 
good in theory and practice, it did not completely overcome the 
defect of the Otto and many other gas engines, the want of 
sufficient expansion. As the exhaust ports opened when the 
motor piston had passed through three quarters of its stroke, 
expansion was necessarily limited. This was a great disadvan- 
tage, but the engine was good in other respects, and more eco- 
. nomical in working than previous motors, and its withdrawal 
from the market is to be regretted. Mr. Clerk calculates the 
actual efficiency indicated by the diagrams as 16 per cent of 
the total heat received, a very creditable result. 

Book Six-Cyole Type. — The Beck engine is the first example 
of a new cycle of operations. It belongs neither to the original 
double-acting two-cycle type, giving an explosion every revolu- 
tion, nor to the four-cycle type of Beau de Eochas, but is known 
as a six-cycle engine. In other words, there is an explosion 
every sixth stroke, or the piston makes three forward and three 



62 



GAB BNGINBS. 



return strokes for three revolutions of the crank. The object of 
thus lengthening the ordinary sequence of operations is to drive 
out more completely the products of combustion by introducing, 
between every explosion and motor stroke, one stroke, forward 
and return, during which a charge of pure air is drawn in and 
expelled. This is called a "scavenger charge/' and was first 
proposed by Mr. D. Clerk, who to a certain extent adopted the 
principle in his engine, though he did not sacrifice two strokes. 
Engineers are even now divided in opinion respecting the best 
method of disposing of the products of combustion. By Otto 
they are purposely retained, in order to diminish the force of the 
explosion, and he and others have thought that there is an 
advantage in diluting the incoming charge with the burnt gases. 
At the same time it must not be forgotten, that these gases help 
to heat the fresh charge before explosion. Other engineers 
are so strongly convinced of the injurious effect of leaving 
behind any portion of the products of combustion that, in 
order thoroughly to get rid of them, they sacrifice a complete 
stroke. The advantage they claim in return for this diminu- 
tion of power is that, the cylinder being thoroughly cleansed, 
the incoming charge is so pure that a much weaker mixture 
may be employed, and more rapid and certain explosion ob- 
tained, than when the products of combustion are allowed to 
remain. With only one explosion every six strokes, there is, 
of course, great difficulty in regulating the speed of the engine, 
and the cooling action on the cylinder walls of the charge of 
fresh air is also considerable. For these reasons the six-cycle 
type has found little favour, and is seldom seen out of England. 
It is best adapted to double-acting engines, adjusted to give an 
explosion every three strokes, first at one, then at the other end 
of the piston. With this modification it has survived to the 
present time; the Griffin engine is a good example. 

The Beck engine was always of the original six-cycle type, 
single-acting, and was never constructed to give more than one 
explosion per six strokes. The working cycle of operations is 
explained by the following table : — 

BevB. of 
Crank. 

S First stroke, [ Admission of 
forward. i charge. 

Second stroke, \ Compression of 



( return. ( charge. 



I Negative stroke \ 
> absorbing 
I power. 



i Third stroke. 
J forward. 
"l Fourth stroke, 
( return. 

! Fifth stroke, 
forward. 
Sixth stroke, 
return. 



,Ignitio„,»plodon.jI'<;;j;^^M»5»^ 

\ expansion. i ""*'■'« 6*'"*» 

J '^ ( power. 

I Discharge and ex- ' 
\ haubt. 

! Admission of pure 
air. 
Discharge of air to 
atmosphere. J J 



Negative stroke 
absorbing 
power. 



Three 
revolntioiis 

' exfuosion 

(one 
cylinder). 



HISTORT OF THB GAB BNGIKE. 



63 



Except with regard to the scavenger charge of pure air, the 
engine resembled the Otto in many respects. Admission and 
ignition were effected by a slide valve not connected direct to 
the excentric from the motor shaft. The slide valve was adjusted 
to make one-third as many revolutions as the crank shaft. The 
compression space was separated from the water jacket by a 
cylindrical layer of non-conducting materials, and the mixture 
was thus ignited in a chamber kept continually at a high tem- 
perature. By introducing the scavenger charge of pure air, and 
by adjusting the admission valves, the richest mixture, namely 
that containing most gas, entered the cylinder first, and the 
poorest mixture was retained round the ignition port. By these 
means it was intended to diminish the shock to the engine, and 
to obtain progressive explosion. An electrical governor was 
employed, and the intensity of the current was made to vary 
wiUi the speed of the engine. According to the variation in 
the speed, the admission of gas was either throttled or wholly 
cut off. The governor was adjusted so that, by moving a weight 
on a lever, the speed could be diminished by 100 revolutions; 
thus the engine, when running empty for a short time, could be 
driven slower, instead of stopping altogether. As a six-cycle 
engine is naturally more difficult to start than a two- or four- 
cycle motor, this is a convenient arrangement. 

Book Trials. — A series of very careful experiments upon a 
4 H.P. nominal Beck 
engine were made in 
London by Professor 
Kennedy, F.RS., in 
February, 1888, and 
published. The indi- 
cated and brake power, 
speed, consumption of 
gas, and jacket water 
were all carefully ob- 
served in six successive 
trials. Two of these 
were made at full speed, 
at 206 and 212 revolu- 
tions per minute, and 
practically at full power, 
the next two at a mean 
speed of 166 revolutions, 
the fifth at 180 revolu- 
tions, with the maximum 
load for that speed, and 



ISO <~0.S90 O^T.- 



I 

•S "<i - 
^ too- 

i 



*i Us *r 

0.181 o-rr. — »k 







Fig. lO.^-Beck Engme— Indicator 
Diagram. 



the sixth with the engine running empty. The highest power 
developed was 8 I.H.P., with 6*3 B.H.P. The maximum pres- 
sure during the working stroke was 74*6 lbs., and at the highest 



64 



OA8 ENGINES. 



speed there were 70*68 explosions per minute. The B.H.P. 
varied from 6-31, with 206*5 revolutions, to 4*84, with 169 
revolutions. Taking the mean of the first four experiments, the 
average consumption of gas was 21*42 cubic feet per I.H.P., and 
26*79 cubic feet per B.H.P. per hour. The gas used was of 
excellent quality, although its calorific value was not very high 
— viz., 611*4 thermal units per cubic foot. The proportions of 
the mixture were 1 1 -5 of air to 1 of gas. One of the diagrams 
of the trial, No. 1, is given at Fig. 19. 

Wittig & Hees. — A vertical engine, by this firm, was 
made for some time in Germany, and tested by Professor 

Schottler in 1881. As in 
the Clerk engine, there is 
a pump and a motor cylin- 
der, and both are enclosed 
in a hollow cast-iron casing 
filled with water, which 
forms the cooling jacket. 
The shaft is above it, and 
both cranks connected to 
the two plunger pistons 
are set at the same angle. 
This is a two-cycle engine 
of the usual type where 
compression is used. The 
pump piston draws in the 
gas and air during the up 
stroke, while the motor 
piston is driven up at the 
same time by the force of 
the explosion and expan- 
In the down stroke the pump 



/t€re 




i^> way 



;; Coimr 



/?;> in 



Fig. 20.— Wittig & Hees En^iDe- 
Ignition Valve (Sectional Plan). 



sion of the charge beneath it. 

piston compresses the gases, and before the end of the stroke 
the pressure opens a valve in a large pipe connectinjnr the 
two cylinders, and thus establishes communication between 
them. Meanwhile the motor piston, in descending, drives out 
the gases of combustion at the beginning of the down stroke 
through the exhaust valve, which is on the op)>03ite side of the 
motor cylinder to the pump, and is worked by a cam on the 
main shaft. When the piston has passed through three-fifths of 
its stroke the exhaust closes, and the products left in the cylinder 
are compressed, while the pump delivers the fresh charge through 
the return valve. During the latter part of the down stroke, 
therefore, both pistons are compressing, and the incoming gas 
and air are thoroughly mixed with the exhaust gases. The force 
of the explosion then closes the return valve, and shuts off 
communication between the two cylinders. The ball governor 
acts upon the gas admission valve. The latter is usually worked 



HISTORY OF THB OAS ENOINE. 65 

hj a cam from the main shaft, which presses down the upper 
movable part of the valve-rod, and opens the valve. If the 
speed is too great, and the balls of the governor rise, a lever 
pushes aside the top of the valve-rod and, the cam being missed, 
no gas is admitted. 

Ignition is effected at the lower dead point by a novel method, 
seen at Fig. 20, also employed in the Sombart engine. An 
external flame, not shown in the drawing, burns in the slide 
cover. When the valve is in its lowest position, the cavity a in 
the slide valve communicates with the flame and, through the 
small channel 5, with the compressed charge from the valve 
chest c, while air is drawn in through an opening near the 
bottom of the slide valve. The mixture in cavity a being 
ignited, the valve rises, cuts off communication with the outer 
flame and the air, and an explosion follows as soon as a com- 
municates at c with the fresh charge in the motor cylinder. 
Thus far the ignition is almost the same as in the Clerk engine. 
In order that the flame may be at the same pressure as the mixture 
in the cylinder, and the light not blown out during the upward 
movement of the slide by the rush of the compressed charge, 
there is a continuous flow of gas through b and the hollows e 
and / into the cavity. In the slide valve are two small pins 
opposite each other; the one is hollow, and flUed with the 
burning gas, forming a continuation of the grove /. The other 
is conical in shape, and fits like an extinguisher over the flame, 
diminishing or increasing the flow of gas, according to the 
position of the slide. 

In a 2 H.P. (nominal) engine, tested by MM. Schottler and 
Brauer, the number of revolutions were 105*5, and the consump- 
tion of gas per I.H.P. per hour 39 cubic feet. In another 4 
H.P. engine, tested by them at the Altona Exhibition in 1881, 
the number of revolutions per minute was 103, and the quantity 
of gas consumed was 43 cubic feet per I.H.P. per hour. Details 
of this experiment will be found in the table given in the 
Appendix. 

In all the engines hitherto descnbed, expansion of the charge 
during one forward stroke, or part of a stroke, of the piston waa 
only in the same ratio as the other operations. Of the two great 
improvements on the original type, compression and expansion, 
the first, compression of the gas and air after admission, already 
formed a part of almost every cycle, but expansion was still 
imperfect. Even now, inventors have not succeeded in increasing 
it so as to utilise to the utmost the high pressures and 
temperatures obtained. Various schemes have been proposed, and 
various methods suggested to remedy this defect. The three 
following engines exhibit different attempts to obtain greater 
expansion, though none of them have succeeded in overcoming 
the initial dif&culties, and in realising a good working cycle. 

5 



66 6A8 ENGINES. 

Seraine. — The type adopted in the Seraine, a vertical engine 
patented in France in 1884, was not in itself new, except as 
applied to gas engines. One cylinder and one piston only are 
used, serving the double purpose of pump and motor ; the crank 
shaft is at the top, above the cylinder. Gas and air are admitted 
in the upper part, and compressed by the up stroke of the piston 
into a receiver below. To make this compression space smaller 
than the explosion space at the bottom of the cylinder, where the 
gases expand — that is, to increase expansion in proportion to 
compression, the piston-rod is of larger diameter and the stroke 
is lengthened, thus the area of the upper face is smaller than 
that of the lower. This type of piston, having a top area less 
than the bottom, is called a differential piston. The working of 
the engine is as follows : — The down stroke draws in air and gas 
at the top of the piston, which are compressed by the next up 
stroke and driven into a receiver. A slide valve worked from 
the main shaft now descends, shuts the exhaust and opens a 
passage for the compressed mixture into the lower part of the 
cylinder. The valve as it rises cuts off the admission, the charge 
at high pressure is forced into an explosion chamber in the 
slide valve, and ignited from a light burning in a hollow. A 
permanent outside flame rekindles the light when blown out. 
The exploded charge, striking back into the cylinder, drives up 
the piston, and expands during the whole motor stroke. The 
exhaust is not opened till the slide valve begins to descend. 
The gas consumption of this engine was said to be only 2 1 cubic 
feet per I.H.P. per hour. It bears a certain resemblance to a 
gas engine patented, but never constructed by Sir W. Siemens ; 
the principle of compression by the upper face of the piston will 
be found in several modern motors. Two drawings of the 
Sei*aine engine are given in Schottler, p. 161. 

Sturgeon. — Another much more complicated two-cylinder 
compression engine, the Sturgeon (Fig. 21), was shown at the 
Exhibition in Manchester in 1887, by Messrs. Wall work & Co. 
Here the problem how to obtain greater expansion in proportion 
to compression was ingeniously dealt with, but at the expens(} 
of simplicity of construction. The method was similar to that 
used in Atkinson's first engine, which certainly resembles the 
Sturgeon, but the means employed were rather intricate. There 
are two cylinders and three pistons. The front or charging 
cylinder £ is horizontal, and its piston p acts as a pump; 
the second or motor cylinder A is vertical behind B and has 
two pistons, F and F'; the four exhaust valves seen at a are 
at either end of cylinder A. The three pistons, shown in the 
drawing, work through their respective connecting-rods and levers 
upon the crank shcdt ; they are all trunk pistons and single- 
acting. The slide valves S between cylinders B and A are 
horizontal, in line with the crank shaft, and driven from it. As 



HISTORY OF TUR OAS ENGINE. 



67 



the piston p of cylinder B moves ont, it draws in the charge of 
gas and air through the slide valve below ; in its return stroke 
it slightly compresses the mixture into the vertical cylinder A, 
and the return stroke of the other two pistons taking place at 
the same moment, the charge is further compressed between 
them. Explosion follows in cylinder A at the in stroke, and all 
the pistons are driven outwards and forwards, but as the pump 
cylinder B is shorter than the other, piston p begins to return 
while the motor pistons are still moving out. Hence, the charge 
it has taken in during the out stroke is compressed into the 
motor cylinder at the moment when the other pistons, near the 
«nd of their out stroke, uncover the exhaust ports, and the corn- 




Fig. 21. — Sturgeon Gas Engine — Sectional Elevation. 

pressed charge from B helps to drive out the products of combus- 
tion. As the motor pistons begin to return the exhaust ports 
are shut, and all three pistons, moving simultaneouBly inwards, 
continue to compress the charge within very narrow limits. The 
principle of the engine is to admit the charge in the smaller, 
and expand it in the larger cylinder, and thus to increase the 
proportion of expansion to admission and compression. The 
•engine attracted attention at the Exhibition by its noiseless 
working, due to the relatively large expansion space, but the 
number of working parts was great, and the construction was 
-soon given up. 

Martini. — A third (French) engine of the same type, the 
Martini, patented in 1883, was first shown at the Paris Exhibi- 
tion of 1889. If made, it does not appear to have worked, but 



68 GAS ENGINES. 

it is interestiBg as presenting another development of the idea 
of increased expansion, afterwards practically and successfully 
treated by Mr. Atkinson. It is a four-cycle engine, in which 
admission and compression are effected during one revolution 
with a shorter stroke, and expansion and exhaust during the next 
with a longer stroke. Like the Otto, therefore, it has only one 
motor stroke in four. The junction of the connecting-rod and 
the motor shaft is effected by levers in the shape of an isosceles 
triangle ; the point of contact describes a double curve forming 
two unequal circles. The larger circle is described by the crank 
during expansion and exhaust, and the smaller during admission 
and compression. The i*atio, or difference in diameter of the 
two circles, depends on the position of this point of junction, and 
the length of stroke can be modified by varying the inclination 
of the axis of the cylinder to the axis of the motor shaft. The 
double circle described by the connecting-rod at the point of 
junction is not symmetrical with the axis of the cylinder, but so 
deviates that the piston approaches the explosion end of the 
cylinder more nearly during compression than during exhaust. 
The automatic ignition is effected in the ordinary way by an 
external flame. The admission and exhaust valves are worked 
by levers from the main shaft. Drawings of this curious engine 
are given in M. Eichard*s* book. M. Mai-tini, whose works are 
at Frauenfeld in Switzerland, now constructs four-cycle engines- 
of the ordinary Otto type. 

Tangye. — A compact and handy horizontal motor, embodying 
several of the improvements already described, and resembling 
in certain respects the Clerk and Seraine engines, was con- 
structed formerly by Messrs. Tangye of Birmingham, after 
Robson's patent. There is one cylinder closed at both ends, 
and the piston-rod works through a stufSng-box. Explosion 
takes place at the back end of the cylinder, furthest from the- 
crank, and with the help of an auxiliary chamber, an impulse- 
every revolution is obtained. At the crank end the charge is- 
admitted at atmospheric, and passed on at slightly increased! 
pressure into an auxiliary chamber, from which it is drawn in* 
at the other end of the cylinder, and compressed, ignited, and 
expanded. The openings for the exhaust are at the crank end*. 
The engine works as follows : — On the crank face of the piston* 
the return stroke admits the mixture of gas and air, and the 
forward (expansion) stroke compresses it into the auxiliary 
chamber at a pressure of 5 lbs. above atmosphere. At the end of 
this out stroke the piston overruns the exhaust ports and reduces 
the pressure in the cylinder below atmosphere. The slight 
pressure of the charge in the receiver is sufficient to lift an 
automatic valve, forming the communication between it and the 
back part of the motor cylinder. A fresh charge enters and 
* Les Moteurs d Oaz, Par G. Richard. 



HISTORY OF THB GAS BKGIKB. 69 

drives out the products of combustion. The return stroke com- 
presses this charge at the front end of the piston, ignition at the 
dead point follows, and the force of the explosion again drives 
the piston forward. Thus one revolution completes the whole 
working cycle, and by storing up the pressure in an intermediate 
receiver, and utilising both faces of the piston, one explosion per 
revolution is obtained. This is an interesting little engine, but 
probably uneconomical, since the gases must be discharged at 
too high a pressure and temperature, and a portion of the fresh 
charge apparently escapes with them. A drawing is g^ven bj 
Clerk.''^ The makers have now adopted the usual Otto type, as 
described in the modem section. 

Victoria. — The ** Victoria" engine, manufactured at Chemnitz 
in Germany, was shown at the Munich Exhibition in 1888. In 
this motor the cylinder is placed vertically on a box-shaped 
base, carrying the bearings for the crank shaft below. The base 
is divided horizontally into two parts. Through holes in the 
upper part the outer air to dilute the charge is drawn, and led 
by a pipe to the admission valves ; the exhaust gases are carried 
into the lower part and there discharged. The piston and 
cylinder above the crank shaft are very long, and the top of the 
cylinder forms a guide. Explosion takes place below the piston, 
driving it up, and the motion is transmitted to the crank shaft 
through a crosshead and two connecting-rods. The admission 
and exhaust valves on opposite sides of the cylinder are worked 
by the same cam on the crank shaft through levers. The gas 
pipe surrounds the admission valve-rod, and gas and air are 
admitted simultaneously. The governor acts by interrupting 
communication between the gas valve and the levers and cam. 
The gases are ignited by a flame through a hollow tube, on the 
same principle as in the Koerting engine ; this ignition tube 
is worked from another cam on the crank shaft. All the valves 
are held on their seats by springs. A drawing is given by 
Schottler. 

Three small gas motors, none of them exceeding 1 H.P., were 
brought out abroad about ten years ago, though they do not 
appear to have found their way into England. In all of them 
the charge was introduced at atmospheric pressure. It was 
difficult, without infringing the Otto patent, to produce single 
cylinder engines using compression. For small powers, there- 
fore, compression and the resulting economy not being of so 
much importance as simplicity, the easier method of firing the 
charge without previous compression was preferred. As the 
temperature in the cylinder was thus reduced, a water jacket^ 
in two of these engines, was dispensed with. The cylinders 
were ribbed externally to afford a larger cooling surface, and 
in this and other respects they resembled the Bisschop. 
♦ Clerk, The Oa9 Eng'vne, p. 196. 



70 GAS ENGINES. 

Eoonomio. — The first was a vertical half H.P. engine, called 
the "Economic" motor, introduced into Europe in 1883 by a 
Oompanj of the same name in New York. The external surface 
of the cylinder is ribbed, and the connecting-rod and piston, from 
which the crank shaft is worked, are attached to a beam. A 
small crank, driven from the main shaft, works a piston valve, 
which uncovers the valves admitting gas and air, and the opening 
into the exhaust. The motor piston draws a charge of gas and 
air into the cylinder through this valve. It is then ignited and 
an explosion occurs, as soon as the working piston has passed a 
platinum disc, maintained at a red heat by an external flame. 
The governing of the engine is ingenious but complicated. On 
the opposite side to the cylinder is an air pump worked from the 
beam. Part of the air thus compressed is used to feed the 
ignition flame, but if the speed increases, and a larger quantity 
of air is introduced, it presses down a disc, cutting off the supply 
of gas. This method was afterwards given up, and the governor 
allowed to act directly on the gas valve. A drawing of the engine 
will be found in Witz*s work.* 

B6nier and Lamart. — The Bonier and Lamart was another 
small vertical non-compression motor, introduced in 1882, which 
was said to combine simplicity and compactness with good work- 
ing conditions. The engine stands on a strong cast-iron base, 
and all the parts are brought as closely together as possible. 
To economise space, the crank shaft is placed alongside the 
cylinder, and the movement is transmitted vertically upwards 
from the piston-rod through a beam and connecting-rod ; the 
stroke of the piston and diameter of circle described by the crank 
are about in the proportions of two to one. The cylinder is 
closed at the top, where admission takes place, and open at the 
bottom. Gas and air enter through a slide valve worked by a 
cam on the main shaft, and h^ld back by springs. As soon as a 
series of holes in the slide are covered by another series in the 
valve face, the out stroke of the piston draws in the gas and air. 
The mixture is ignited by a flame carried in a cavity of the 
slide, and lit after each explosion by an external light; the 
exhaust on the opposite side of the cylinder is worked by a 
separate cam. Thus during the first half of the down motor 
stroke, the charge of gas and air is drawn in, explosion and 
expansion occupy the second half, and the return stroke drives 
out the products of combustion. The cylinder is water-jacketed 
in the ordinary way. In another and apparently an earlier 
horizontal type of this engine, described with drawings by 
Schottler, cylindrical air tubes, open above and below, are 
carried through the jacket to keep the water cool. The gas 
consumption of this engine is said to be 49 cubic feet per I.H.P. 

• Trait6 TJUorique €t Pratique des Moteurs d Oaz, Par Aimg Witz. 
Paris, 1892. 



HISTORY OF THE GAS ENGINE. 71 

per hour. A drawing will be found in Witz, p. 229. A descrip- 
tion of the Bonier hot air engine is in Part II. 

Forest. — The Forest engine, brought out in France in 1883, 
differs very little from the Bonier, except in one respect. Instead 
of a water jacket, the external portion of the cylinder is sur- 
rounded with deep ribs in the form of a screw, giving a large 
air-cooling surface. The cylinder is horizontal, and the charge 
is admitted and ignited at the front end nearest the crank. 
Power is transmitted from the piston by a lever and connecting- 
rod to the crank shaft. Gas and air are admitted in the same 
way as in the Bonier, through openings in the slide and slide 
face, while the cover, acted upon by the governor, shuts off these 
openings more or less according to the speed. The ignition and 
exhaust are also regulated by this slide valve, placed alongside 
the cylinder ; it is worked by a cam on the shaft, and held back 
by a spring. A projection in the side of the cylinder, opposite 
the slide valve, causes the mixture to pass in a zig-zag direction 
before the ignition opening. Here it is ignited when the piston 
has travelled through one-third of the stroke ; an outside flame 
periodically rekindles the gas jet. Thus admission is effected 
when the slide valve is at one end, and ignition when it is at 
the other end of its stroke ; when in its central position the 
gases are discharged into the exhaust. The consumption of gas 
is about the same as in the Benier. Drawin<<s of the Forest 
engine are given by Schottler and Witz. A much more impor- 
tant type of this motor, driven by petroleum, with reversible 
action, and intended especially for marine use, is described in 
Part IL It is to this class of engine that M. Forest has more 
particularly devoted himself 

Ewins and Newman. — Another small non - compressing 
single cylinder horizontal engine, brought out in 1882 by Ewins 
and Newman, is distinguished by its somewhat peculiar method 
of ignition. By the forward stroke of the piston, gas and air 
are drawn into a mixing chamber at the back of the horizontal 
cylinder, from which the chamber is separated by a flap valve. 
The charge is ignited by an outer flame, as soon as a slit in a 
notched revolving disc, worked by a catch from the crank shaft, 
is brought to face a similar opening at the back of the cylinder 
opposite the flame. The exhaust valve is also opened by the 
main shaft, and the return stroke expels the products of com- 
bustion. The engine is evidently constructed to run at a greater 
speed than is usual with such small motors. 

Francois. — The Fran9ois, a vertical engine brought out in 
France in 1879, bears a strong resemblance to the Bisschop. As 
in the latter, the explosion of the charge is utilised to force up 
the piston, and the atmospheric pressure to drive it down. The 
crank shaft is not in the same line with the axis of the cylinder, 
and the piston works upon it by means of two connecting-rods, 



72 GAS ENGINES. 

two cranks, and two flywheels. Gas and air are admitted, 
ignited and discharged at the bottom of the cylinder. There 
are two slide valves, one within the other. The larger one, 
containing the openiugs for the exhaust and the igniting flame 
is hollow, and held against the side of the cylinder by the slide 
cover and lateral cheeks. The smaller valve is solid, and there 
is a space between the two, varying with their position. Both 
valves work to a certain extent independently of each other. As 
the smaller moves, gas and air are admitted from the cover 
through the openings left between the valves, and pass to the 
cylinder. 

Warohalowski. — All these small engines belonged to the 
older non-compressing types, but an interesting little compres- 
sion engine, designed by Warchalowski in 1884, and made by 
Horde & Co., of Vienna, was shown at the Antwerp Exhibition 
in 1885. It was compact and carefully designed, and differed 
very slightly from the Otto. The vertical cylinder was at the 
top. The governor regulated the supply of gas, by means of a 
projection, acting on the admission valve for a longer or shorter 
time, according to the speed. 

Noel.'— Several small engines obtained a certain reputation in 
France, and a few are still made. One of the best is the Noel, 
brought out in 1888, and shown at the Paris Exhibition in 1889. 
It is remarkable because, like the Warchalowski, it is one of the 
few four-cycle engines constructed for small powers, from J H.P. 
upwards, and using compression. As in the "Economic" motor, 
there is one cylinder, kept cool externally by radiating ribs. In 
one type the piston works horizontally, and drives the main shaft 
below it through a beam and crank. The admission and distri- 
bution valves are simple lift valves, instead of the ordinary slide 
valves. They are driven by an auxiliary shaft, geared 1 to 2 from 
the main shaft. Air is drawn in automatically from the base of 
the engine, and ignition is obtained by the electric spark, the 
governor when required wholly cutting off the admission of gas. 
Another vertical type is also made, and drawings of both are 
given in Witz, p. 324. The engine can be driven with car- 
buretted air. 

Durand. — The Durand, a four-cycle horizontal engine, also 
exhibited at Paris in 1889, is adapted for working either with gas 
or carburetted air, and the inventor proposes to drive it with 
eas when small powers are required, and with carburetted air 
for high powers. Carburetted air is air highly charged with vola- 
tile petroleum vapour. The engine will be desciibed among the 
petroleum engines, and one point only needs to be mentioned here. 
Ignition is by the electric spark, and M. Durand has utilised an 
idea first suggested in Germany. The two wires are attached, the 
one to a metallic point, the other to a toothed wheel, making one 
revolution for eight of the motor crank. The point rests against 



HI8T0BT OF THE GAS BNGINS. 73 

the wheel, and a spark is produced each time it slips from one 
tooth to the other. By this friction of the two parts in contact, 
the metal is kept clean, and there is no danger of the spark 
failing. 

Mire. — Another small engine, the Mire, made from \ H.F. to 
2 H.P., was also brought out in 1889. Like the Clerk it has a 
motor and pump cylinder, and an explosion at each revolution. 
It is one of the very few gas engines, the action of which can be 
reversed, and the engine worked either backwards or forwards. 
This is rather a difficult operation, and gas engines are, therefore, 
seldom adapted for river boats. The Mire can be driven with 
gas or petroleum. 

Two other small French engines, the Laviornery and the 
Etincelle, have no special distinguishing features. The first is a 
non-compressiou vertical engine, invented in 1880. The second, 
made by Gotendorff & Cie. of Paris, is a fourcycle horizontal 
compression motor, with electric ignition, and a hollow base 
serving as a water jacket, as in the Wittig and Hees engine. 
Both were exhibited in Paris in 1889. 

Baldwin. — An interesting and more important engine than 
the two last is the "Baldwin," introduced from America in 1883. 
like the Mire it is of the Olerk type. It has one horizontal 
cylinder divided into two parts, the back forming the motor, and 
the front the pump end. Gas and air enter the front, and are 
thence compressed into a reservoir. An automatic valve is 
lifted as soon as the pressure in the cylinder is reduced, and 
admits the compreissed gases from the reservoir into the combus- 
tion chamber at the back of the cylinder, with which the chamber 
communicates only through a small aperture. Here the explo- 
sion takes place, and the ignited mixture enters the cylinder 
exactly in the centre, the smallneas of the opening preventing 
its dilution with the products of previous combustion. This 
arrangement has been superseded in later engines by an apparatus 
called a " retarder," and the inventor maintains that none of the 
fresh charge escapes with the exhaust gases. Ignition is effected 
by the electric current, from a small dynamo driven from the 
main shaft. To generate the spark at starting, there is a second 
pulley to the dynamo, smaller in diameter, and revolving more 
rapicUy than the ordinary driving wheel, which is used until the 
engine is in full work. Three different methods are employed 
to regulate the speed, first, by diminishing the volume of the 
mixture, secondly, by partial, and thirdly, by total suppression 
of the gas, according to the greater or less excess of speed. The 
ball governor acts on the admission valve ; the engine is cooled 
by a water jacket, and works with great regularity. A drawing 
of the Baldwin engine is given by Witz, p. 254. 

Various. — Other engines which scarcely outlived the time of 
their invention were the Lindley (1882) compound, with two 



74 OAS ENGINES. 

cylinders ; the Nortbcote, in which the steam generated in the 
water jacket was utilised to increase the pressure ; and the 
Laurent, employing a regenerator. Three attempts were also 
made, about 1883, by Fielding, Bull, and Butcher, to construct 
reversible engines, but without mucli success. Butcher further 
proposed to regulate the length of stroke by the governor. In 
the Alliaume engine the cylinder was cooled by vertical pipes 
in which air circulated constantly. Other engines were Linford, 
1878 ; Funck, 1879, the first engine to use ignition by a hot 
tube; Maxim, 1883; and Taylor, exhibited in the English 'sec- 
tion of the Paris Exhibition of 1889. 



CHAPTER VII. 
THE OTTO GAS ENGINE, 1876. 

Contents. — Orisinal Type — Parts— Slide Valve — Ignition— Distribution — 
G o vemor —Stratification — Tube Ignition — Modern Types — Trials — 
The Lanchester Self-Starter. 

It is to Otto, the celebrated German engineer, that the honour 
belongs of having first produced a practical working gas engine 
using compression, and giving an economical cycle of operations. 
The Otto engine was brought out at a time when, in the com- 
petition between gas and steam, the balance inclined so much 
in favour of the latter, that it even seemed possible that gas 
engines would be driven altogether from the field. The con- 
struction of the Lenoir and Hugon engines had been more or 
less relinquished, on account of the quantity of gas they con- 
sumed. Of all their successive imitators, none supplied the 
long-felt want of an engine working as steadily and economi- 
cally as steam, always ready for work, where a steam engine 
could not be used. The Otto and Langen engine, which fol- 
lowed the Lenoir and Hugon, was never popular, owing to its 
unsteadiness, noise, and irregularity. The inventors were fully 
cognizant of these defects, and for years they laboured to remedy 
them, working on the principle of admitting the gas and air at 
atmospheric pressure. At length, however, to the surprise of 
the engineering world, they gave up altogether this method of 
construction, and patented in 1876 an engine, shown at the 
Paris Exhibition of 1878, which differed considerably from any 
hitherto made. 

CompreBBion. — The important innovation introduced in the 
Otto engine was the compression of the charge of gas and air 



THB OBIGINAL OTTO GAS ENGINE. 75 

before ignition. The advantages of this method have been 
already described. Beau de Rochas had in 1862 laid down the 
axiom in his patent, that no gas engine could be economical, 
unless its cycle included compression of the mixture after admis- 
sion. Yet, although the extravagant consumption in gas engines 
was universally admitted, no one proposed to adopt compression 
as a means of diminishing it, till Otto's engine appeared. Even 
the inventor himself did not seem to understand the radical 
nature of the change he introduced. He attributed the reduc- 
tion in the consumption of gas and the popularity of his engines, 
not to compression, but to the stratification of the charge as it 
entered the cylinder. The novel method of admission and ignition 
was expressly protected in the patents. Whatever the cause, the 
success of this engine was from the first undoubted, and practi- 
cally, for many years after it was brought out, few others were 
sold to any large extent. For this reason, and on account of 
its excellent design and workmanship, it will be useful to con- 
sider carefully the constructive details and working of the Otto 
engine, although it was patented as early as 1876. 

Origincd Otto. — In this motor, the whole cycle advocated by 
Beau de Hochas is efiected in one cylinder, in accordance with 
his patent. The cycle is divided between four piston strokes, 
two forward and two back (two revolutions), and one explosion 
or motor impulse is obtained for every four strokes. The 
original type of the engine is horizontal, and the end of the 
cylinder nearest the crank is open. The first stroke of the 
piston towards the crank (forward) draws in the charge ; the 
second stroke (return) compresses it, and ignition follows at 
the inner dead point. In the third stroke (forward) the force of 
the explosion drives the piston, and in the fourth stroke (return) 
the products of combustion are discharged. The third is the 
only motor stroke, in which the pressure of the gases produced 
by explosion causes them to expand, forcing out the piston, and 
performing actual work. All these operations are carried out 
and completed at the end of the cylinder away from the crank, 
and on one side of the piston only. 

At this working end there is a large clearance space, comprising 
about four-tenths of the whole volume of the cylinder, into which 
the charge is compressed, and where ignition takes place. As 
the piston does not enter this clearance, the gases of combustion 
can never be completely expelled, but a portion is always left in 
the compression space to mingle with the incoming charge. Otto 
considered that it was an advantage thus to retain a part of the 
products of combustion, to act as a cushion against the piston, and 
deaden the shock of the explosion. As only one motor impulse 
is given in four strokes, the motion for the other three must be 
obtained from the impetus of the moving parts. Hence the fly- 
wheel is made larger and heavier than usual. There is one other 



76 



QAB BNGINS8. 




peculiarity of stmcture to be mentioned, in studying the original 
Otto type. In most gas motors the charge itself is carried past 



THB ORIGINAL OTTO GAB SNGINB. 



77 




the flame, or ignited by an electric spark. Here the gas is 
supplied for three different purposes through separate pipes. 



78 



GAS BKOIKE8. 



There is first the supply pipe, providing gas to mix with air for 
the charge, and controlled by the governor; another for the 
permanent outside flame ; and lastly, a branch pipe feeding a 
small intermediary chamber in the slide valve, which communi- 
cates first with the outside flame, then with the compressed 
mixture, and flres the charge. The arrangement has been 
modified in the later engines. 

Fig. 22 gives a side elevation. Fig. 23 a plan of an 8 H.P. 
motor, and Fig. 24 an end view of the Otto engine. The dif- 
ferent parts are similarly lettered in the three drawings. A is 
the motor cylinder, and P the piston, shown in Fig. 23 at its 
furthest point in the in stroke, with the compression or clear- 
ance space behind it. At the crank end the cylinder is open. 
The piston-rod is keyed to the crosshead P, to which the con- 




Fig. 24.— Otto Engine— End View. 

necting-rod 0, working on to the crank shaft K, is also attached. 
R is the counter shaft, driven by the wheels E and F from 
the crank shaft, and revolving at half the speed of the latter. 
This shaft R has many functions to perform. Through a crank 
H and small lever I it drives the slide valve S, where the charge 
is admitted, ignited, and exploded. Below is G the ball governor 
acting upon the gas valve L, and regulating the supply ; a cam 
and tappet t upon the counter shaft open the exhaust valve e 
once in every revolution ; and, lastly, a strap from it drives the 
oiling gear D above the cylinder, and supplies oil as long as the 
engine is working. The cylinder is surrounded by a water 
jacket W. It has two openings, a and 6 — a is the charg^ig port, 
filled first with gas and air at atmospheric pressure from the 
distributing chamber in the slide valve, and then with part of 



THE ORIGINAL OTTO GAS ENGINE. 



79 



the compressed chargei and through this port a tongue of flame 
shoots into the cylinder, and explodes the remainder ; 6 is the 
opening for the exhaust, and the gases of combustion pass out 
at e. Below at m is another opening through which air is 
admitted into the slide valve, mingles with the gas, and is 
carried forward until, at a, it enters the cylinder. 

In Fig. 24 the double branching of the gas pipe to supply the 
permanent outside burner, and the temporary flame, is seen at B|. 
The slide valve S is worked by crank H and lever I ; e is the 
exhaust opened by lever ^, and the cam t on the counter shaft. 
The governor works upon the gas valve L by a series of levers, 
r, r\ while a handle at r"" regulates the admission of gas to the 
valve from the rubber gas bag. 

^^ Slide Valve. — The slide valve of this engine is an ingenious 
piece of mechanism. There is first the face next the cylinder. 



Air' in' 










Moving 
Slide 



/f \ Cowr 



Fig. 25.— Otto Engine, 1876— Sectional Plan of Slide Valve. 

secondly, the valve proper, and, thirdly, the cover on the out- 
side ; the latter is held against the valve by springs and screws. 
The slide valve alone is driven to and fro ; the other parts are 
fixed. Fig. 25 gives a sectional plan of the three parts, and 
their connection with the cylinder. Here A represents the 
cylinder, E the slide face, S the slide valve, and I) the cover. 
W is the water jacket, a the charging port introducing the mixture 
into the cylinder, m the opening in the slide face for admitting 
the air, which passes at o into a chamber in the slide valve with 
three openings, Q and M, and n opening to the slide cover. 
Shortly after, as the slide valve passes from right to left, the gas 
is admitted from L in the cover, through n into the chamber. 
Continuing its motion in the same direction, the slide next 
brings the opening Q of the chamber opposite a, and its con- 
tents are discharged into the cylinder, to be there compressed by 
the next back stroke of the piston. 



80 



GAS EN0IKE8. 



Meanwhile, at the other end of the slide valve, a different 
series of operations have been taking place at the same time. 
At B is the permanent burner in the slide cover, open to the 
atmosphere. While the slide valve passes from right to left, 
the chamber N is brought opposite B, but as it contains no gas 
no ignition occurs. But as soon as it reaches d, gas from the 
third pipe is introduced into it through a grooved hollow in 
the cover. Before the slide valve commences its return move- 
ment, and while the mixture is being compressed in the cylinder,. 









■ 


■• 


Q 


'8 

O 


jr 





Fig. 26.— Otto Engine— Vertical View of Slide Valve. 

the chamber N is tilled with gas from dy ignites on passing before 
B, and when brought opposite the cylinder port a fires the 
charge. It is necessary, however, to equalise the pressure of' 
the gas flame and of the charge, lest the flame be blown out. 




Fig. 27.— Otto Engine— Vertical View of Slide Cover. 

As long as the small lighting port is in communication with the 
atmosphere through B the flame is easily maintained, but as the 
slide moves onward, and connection is cut off, it begins to 
fail. Therefore, before it reaches a, a hole is passed in the slide 
face, communicating through a T-shaped passage with the charg- 
ing port. A small portion of the compressed charge passes 
through it to the flame in N, and establishes an equilibrium of 
pressure between the mixture in the cylinder and the flame, 
before the latter reaches and tires the charge. 

Figs. 26 and 27 give a vertical view of the slido and slide 
cover. In the latter L is, as before, the pipe to admit the main 



THR ORIGINAL OTTO GAS ENGINE. 



81 



supply of gas, B^ is the smaller gas pipe feeding the permanent 
flame B, Fig. 25, which burns at the bottom of a chimney. 
Through another small pipe the gas passes at d. Fig. 27, and 
through the grooved passage d' to the lighting chamber N, Fig. 
26. Above this chamber is the hole at % through which, and a 
passage in the slide face, communication is established between 
the cylinder and the light, as soon as the slide passes the open- 
ing of the passage. At c c, Fig. 26, are the holes for the gas 
entering the admission and distribution chamber M Q. Figs. 
28 and 29 show a vertical section of the slide valve and cover, 
with the arrangement of the ignition flame. The parts are 
lettered as before. N is the lighting chamber in the slide, B the 




LI 

Fig. 28.— Ignition Flame 
and Slide Valve. 




Fig. 29.— Ignition Flame 
and Slide Cover. 



permanent burner in the slide cover. In Fig. 28 the flame at N is 
shown while being formed. Air enters from below, gas through 
the groove d\ corresponding with the opening d in the slide 
cover, Fig. 25, and passes through this T-shaped channel into N. 
The chamber being in communication with the flame burning 
in the chimney, the charge in it is ignited. Fig. 29 gives a view 
of the intermediary flame in chamber N, after it has been cut off 
from the outer burner, and from the gas pipe d. The T-shaped 
passage d' here opens on the other side into the cylinder port 
through if and a small portion of the compressed charge passes 
through into N. Shortly after, the port is brought opposite the 
cylinder port a and ignition follows. Thus during one piston 
stroke three operations take place, and the slide valve has to 
form and kindle the intermediary flame, equalise the pressure 
between it and the charge in the cylinder, and ignite the latter. 
The method by which all these various actions are timed to 
occur is ingenious. Fig. 30 gives a diagram of the proportional 

6 



82 



GAS ENGINES. 



movements of the motor crank, the counter shaft, and the slide 
valve. The Roman figures represent the positions of the crank, 
the Arabic figures those of the counter shaft, while the letters 
a, by c, d, show the movement of the slide valve. 

As the motor crank moves from I. to II. in the direction of the 
arrow, the crank on the count'Cr shaft which is set at an angle 



thi* 
Sidt 




— r— fiT— -JT-' 






ital 



Fig. 30. — Otto Engine— Positions of Crank, Counter Shaft, and Slide Valve. 

of 45** behind it passes from 1 to 2, and the slide valve moves 
from a to 6 and back again. During this time the piston moves 
out, and the fresh charge is drawn at atmospheric pressure into 
the cylinder. Fig. 31 gives this position at A. Air is admitted 
at m, gas at N, and both after mixing in chamber M Q (Fig. 
25) pass through a into the cylinder. The next crank movement 
completing the first revolution is from II. to III. (Fig. 30); the 




^iV 



Air -^ 



H 



GtX4 





Fig. 31. — Otto Engine— Positions of Ports and Passages. 

counter shaft moves from 2 to 3, the slide valve from a to c. 
Fig. 31, B, indicates the position of the slide valve. All the 
ports of the cylinder are closed, while the piston compresses the 
charge. The lighting chamber is brought opposite the per- 
manent flame and fired, and through the port for equalising 
the pressure, part of the charge in the cylinder is also compressed 
into it by the return movement of the piston. Position III. 



THE ORIGINAL OTTO GAS ENGINE. 83 

(Fig. 30) represents the inner dead point; ignition and explosion 
take place, and drive the piston through its second forwwl and 
only motor stroke. The crank shaft revolves from III. to IV., 
the counter shaft from 3 to 4, the slide valve passes from c to c^ 
and back again. Fig. 31, G, shows the progress of the slide 
during and after the ignition of the charge. From lY. to I. the 
crank completes its second revolution, the counter shaft passing 
from 4 to 1 concludes one revolution, and the slide valve moves 
from c to a and takes up position D (Fig. 31). All the admission 
ports are closed to the cylinder, while the products of combustion 
are driven out through the exhaust by the second return stroke 
of the piston. 

By this arrangement air enters the mixing chamber M (Fig. 25), 
and is passed on into the cylinder, during nearly the whole of the 
admission stroke, but gas is only admitted during the latter part. 
The two ports are so proportioned that the ingress of air is first 
cut off, and gas enters alone at the end of the stroke. The effect 
of this distribution on the stratification of the charge will be 
discussed further on. 

Fig. 32 gives a view of the exhaust valve. The lever opening 
it, K, shown also in Fig. 24, passes beneath the motor cylinder A, 
and is worked by a cam, ^, 
on the counter shaft R. The 
end of the lever is held 
against the counter shaft by 
a spring. At a given moment 
the cam t presses one end of -'^^^^ 
the lever down, and the 

other raises the lifting valve _^ 

s; b is the opening into the Fig. 32.— Otto Engine— Exhaust Valve, 
cylinder, and e the discharge 

into the exhaust. When valve «' is raised, the action of the 
piston drives the products of combustion through b and e. The 
cam being one-quarter the circumference acts upon the valve 
during one-quarter of a counter shaft revolution, or one stroke 
of the piston. A second cam upon the other side of the shaft 
can also be adjusted to push down the lever, and hold open the 
valve, when starting the engine, during the compression as well 
as the exhaust stroke. This method of diminishing the pressure 
in the cylinder while starting has been adopted in other engines 
besides the Otto. The second cam is easily disconnected from 
the shaft, as soon as the engine is at work. 

The speed of the engine is regulated as shown in Figs. 22 and 24, 
pp. 76, 78. Upon the counter shaft R is a socket with a tappet o, 
having a similar action to the exhaust cam. When the shaft is 
revolving at ordinary speed, this tappet regularly catches and 
pushes up one end of the lever q, resting upon it, the other end 
of which terminates in the rod r, opening the gas admission 




84 



GAS ENGINES. 



valve L. But if the speed increases, the balls fly out and push 
up another small lever u, ivhich, forcing the socket to one side, 
causes the tappet o to miss the end of the lever q. Nothing but 
air is admitted, and no explosion follows until the speed is 
reduced, and the tappet being again in position acts upon the 
gas valve. The handle 8 (Fig. 22) is intended to raise the balls 
only when starting the engine, and falls back automatically after 
the first explosion. 

Two methods were available for regulating the speed, either 
to cut off wholly the supply of gas, or to decrease the quantity 
admitted ; the former was preferred as being more economical. 
No gas could then pass unburnt through the cylinder, but, as an 
explosion was missed every time the gas valve was closed by the 
governor, the speed became irregular. Otto was obliged, there- 
fore, to modify the governing gear when the engine was used to 
drive dynamos for electric lighting, where a very steady speed was 
required. Instead of the tappet, a cam with various steps acted 
upon the lever q. When the speed fluctuated within slight 
limits, the cam opened the gas valve for a longer or shorter time, 
and varied the strength of the charge. The explosions were 
sometimes weak, sometimes strong, but never wholly missed, 
unless the speed was so greatly increased that the wheel of the 
lever slipped quite off the cam. Latterly, for small motors. Otto 
adopted the pendulum type of governor, which is frequently met 
with in modern engines. It consists of an oscillating weight at 
the end of a rod, swinging backwards and forwards with the 
motion of the engine and of the slide valve, to which it is 
attached. As long as the speed is normal, a horizontal rod, 
connected to the pendulum, fits at each revolution into the 
notched end of the valve-rod opening the gas valve. But if the 
speed and the motion of the slide valve increase, the swing of 

the pendulum cannot overtake them. 
The weight shifts the rod out of 
position, a miss fire occurs, and no 
gas is admitted until the speed of 
the engine is reduced. 

The lubrication of the Otto engine 
is simple and ingenious. Great care 
was necessary in oiling all the parts, 
especially the slide valve. Fig. 33 
shows a vertical section of the oiling 
apparatus. An external view with 
the two lubricating pipes is shown 
at D, Fig. 22, p. 76. This apparatus is 
worked by means of a small pulley, 
a, and a strap on the counter shall. 
The cup is filled with oil into which a small wire, 6, on the same 
shaft as the pulley, dips at every revolution. The drop is wiped 




Stctional Elevation, 
Fig. 33.— Otto Gas Engine- 
Oiling Apparatus. 



THB OTTO GAS BKOINB. 85 

off on a fixed pin, c, placed over a trough. From the trough 
it runs into one of the two pipes, and is carried either to the 
piston or the slide valve. Sometimes this arrangement is made 
in duplicate, and the cup divided vertically. Two kinds of oil 
can be then used at the same time, the better quality for lubri- 
cating the slide valve, and a coarser oil for the piston. In this 
apparatus the oil is kept cool, and lubrication is automatic and 
continuous. 

For starting small power engines, the additional cam to keep 
the discharge valve open during compression as well as exhaust 
was found sufficient. But the Otto motors were soon applied to 
larger powers (over 20 H.P. nominal), and it then became impos- 
4Bible to start them without a special apparatus. The German 
Otto firm often use a small, to start a larger gas engine. In 
the two-cylinder 30 H.P. gas motors driving the dynamos 
lighting the Cologne Theatre, a small 2 H.P. engine is employed 
to set them in motion ; when they are once started the little 
engine stops. 

Few engines more ingeniously constructed than the Otto have 
yet appeared, and even now, when so many later motors have 
been brought out, it is still one of the most economical, {"or 
many years after its introduction in 1876 it was almost the only 
practical gas engine made. More than 30,000 engines were sold 
in about ten years, and according to the German firm 35,000 
engines, with a total of about 150,000 H.P. had, up to 1892, been 
constructed by them. 

Otto himself attached, as we have said, the greatest importance 
to his system of admitting the charge. The slide valve is so 
-constructed that pure air enters first, and passing into the 
cylinder mingles with the products of combustion left from the 
previous charge, which the piston (as it does not enter the 
clearance space) cannot expel. Hence, next the piston, there is 
said to be a weak mixture, which is intended to deaden the 
shock, to retard combustion, and to take up some of the heat 
developed by the explosion. Gas next enters the slide valve and 
.mixes with the air, and this layer, on reaching the cylinder, forms 
a dilution of medium strength, the proportions being about 7 of air 
to 1 of gas. Finally, by the movement of the slide valve pure gas 
alone, without any admixture, is admitted into the cylinder. It is 
this gas which, through the grooved passage in the slide valve, 
feeds the burning light, and causes it, as Professor Witz says, to 
shoot into the poorer mixture like a tongue of flame. Thus there 
are three strata in the cylinder, of three different degrees of rich- 
ness, the mixture nearest the piston being so diluted that it will 
not ignite, except by the force of the explosion. The flame is 
supposed to leap from one layer to another, producing the slow 
^combustion so much desired by Otto. Many eminent scientific 
.men supported his theory of stratification, while others were 



se 



GAS ENGINES. 



strongly opposed to it. Perhaps the best proof that it does not 
really take place in the manner supposed, is furnished by the 
makers of the Otto engine in different countries, who have 
abolished the slide valve, and substituted admission by lift 
valve, without any effect on the action of the engine. 

The patents for the Otto engine, which have now expired, 
were formerly acquired in England by Messrs. Crossley Brothers, 
of Manchester ; in France, by the Compagnie Fran9aise des 
Moteurs k Gaz ; in America, by Schleicher, Schumm <fe Co., of 
Philadelphia. The German firm have long been established near 
Cologne. 

Several of these firms, while adhering to the principle of the 
original type, have made many alterations in the working details. 
Messrs. Crossley have introduced ignition by a hot tube, instead 
of by a flame carried in the slide valve. Fig. 34 gives two views 

of this method of ignition, 
as used for many years; it 
has recently been again 
modified. C is the passage 
into the cylinder, T the 
cast-iron tube, and K the 
asbestos lining of the chim- 
^ I '-'^ ■' iji W\)'" ^^^' '^^^ *^ ^^ closed at 

Ijfi-d: I 1^ .^. ^liJtf^!- , , *^® *^P» ^^^ kept at a red 

heat by a Biinsen burner, B. 
During the compression 
stroke a cam on the counter 
shaft lifts the lever L, and 
pushes up the timing valve 
E into the port D. No 
portion of the compressed 
charge can, therefore, enter 
the tube, and any burnt 
gases left in it escape 
through A into the atmo- 
sphere. At the inner dead point, when the piston has com- 
pleted the compression stroke, the cam leaves the lever L 
free, E is drawn down by the spring S, and the compressed 
mixture, rushing into the red-hot tube, is there fired and ignites 
the charge. G and F are outlet channels for discharging the 
burnt gases through A. Thus a rich mixture alone enters the 
tube, and ignition is certain. By this method the pressure of 
the charge is utilised, and is made to fan the flame instead of 
blowing it out. 

As the Otto engine became more popular, and larger sizes 
were made, the cost of working it with town gas was found to 
be heavy, especially on the Continent, where coals are generally 
dearer than in England. Several methods were introduced for 





34. — Otto Engine— Ignition 
Tube. 



THE OTTO GAS ENGINE. 87 

making gas in ore cheaply than by distillation from coal. These 
will be described later on ; the system most generally used is 
Mr. Dowson's cheap gas producer, which, when applied to any 
engine, reduces considerably the cost of working, as compared 
with town gas. This gas, usually generated on the spot, is 
economical only when employed for larger engines. As it is much 
poorer than lighting gas, it requires to be diluted with a smaller 
propoi*tion of air ; the ratio is generally about 1 of Dowson gas 
to Ij^ of air. In the Otto engine certain modifications in the 
size of the gas and air valves were formerly necessary. Gener- 
ally speaking, however, when it is desired to drive a motor with, 
cheap or Dowson gas, the makers prefer to supply an engine 
especially adapted to the purpose. 

For powers over 30 H.P., the makers of the Otto now often 
use engines having two cylinders side by side, and two sets of 
yalyes, driven from a single auxiliary shaft placed between them. 
One governor regulates the speed. The two motor cranks are 
in the same plane, working on one shaft, and the two piston 
rods are 180** apart. The forward stroke of one is the motor 
expansion stroke, while, at the same time, the other piston 
draws in the charge. In the two following strokes, the one piston 
compresses the charge, and the other drives out the products of 
combustion. Thus a motor impulse is obtained alternately from 
each piston, for every revolution of the crank shaft. Messrs. 
Grossley make engines of this type, indicating 170 H.P. ; the 
German firm bring them out up to 200 H.P. These twin-cylinder 
engines are also used for electric lighting, on account of their 
regularity in running. They can be worked either with coal gas 
or cheap gas. A two-cylinder engine indicating 30 H.P. was 
shown at the Electrical Exhibition at Frankfort in 1891. Each 
cylinder was complete in itself, with hot tube ignition and 
admission valvesj and could be worked alone. Gas was supplied 
from a receiver controlled by the governor, which could be dis- 
connected from one cylinder, and made to act upon the other 
only, if less power was required. In all modem Otto engines hot 
tube ignition is used. Messrs. Grossley also make an engine, as 
shown in Fig. 35, with two cylinders opposite each other, work- 
ing on to one crank. 

In 1879 Otto made an attempt to apply the compound prin- 
ciple of expansion to gas motors, and constructed an engine 
with three cylinders and pistons, all single-acting. Between the 
two cylinders, in which explosion took place alternately, a third 
was introduced where the charge was furtiier expanded. The 
cranks of the three pistons were set at such an angle to each 
other that explosion was continued in the third cylinder at 
each forward stroke, while the first of the two other pistons 
drove out the products of combustion, and the second drew in 
the charge. Thus the expanding cylinder co-operated alternately 



88 



GAS ENGINES. 




I 
I 
I 
I 

o 



•I 



TH£ OTTO OAS BKOINE. 



89 



with the others in each consecutive motor stroke, receiving 
the charge for expansion first from one, then from the other, 
And an impulse for each crank revolution was obtained. This 
type of construction seems to have been soon abandoned, and 
Professor Witz is of opinion that the friction and the greater 
cylinder wall surfaces exposed to the hot gases, and carrying off 
their heat, would destroy the advantage of increased expansion. 




Fig. 36.— Otto-Croesley Domestio Motor. 

For large and medium powers, the horizontal type of engine 

is always used. A demand, however, soon arose for small, light 

engines, occupying little space, and the *' Domestic Motor," Fig. 

36, for two-man power, was brought out to meet this require- 

.ment Being vertical, it is more compact than a horizontal 



90 GAS ENGINES. 

engine, and can easily be transported. It has few parts, and 
these are as simple as possible. A pendulum governor acta 
on the gas valve through a vertical rod with knife edge, catching 
at a given moment into a projection, which lifts the valve admit- 
ting the gas. If the speed increases, the pendulum swings back 
this rod, the knife edge is missed, the gas valve is not opened,, 
and no explosion occurs. In this engine, as made by Messrs. 
Crossley, gas and air are admitted through a rotatory valve inta 
the cylinder. In the German type, the ignition tube is not shut 
off by a valve, but is always open to the cylinder, and a certain 
quantity of the gases of combustion, therefore, remains perma- 
nently in it. The compression stroke forces this residuum and 
part of the fresh charge up the narrow passage leading to the 
hot tube, and causes ignition. This type of motor is made in 
sizes up to li H.P. 

The Otto engine, described in detail in the beginning of thia 
chapter, is of the original type brought out in 1876, and various 
modifications and improvements have since been made, especially 
by Messrs. Crossley. In their motors, as now constructed (1893),. 
the slide valve has been abolished for all sizes of engine, and air 
and gas are separately admitted through lift valves, worked by 
cams on the counter shaft The exhaust lift valve, worked by 
a cam and levers, has been retained. The modem ignition by 
hot tube, instead of a flame in a cavity, has been described 
already. Communication between the cylinder and the tube 
is generally made through a timing valve, worked by a cam. 
A patent pendulum governor or a ball governor is used. The 
counter shaft is driven by worm gear from the crank shaft, the 
oiling is practically the same as that of the original type. 

Most Otto engines are provided with a safety apparatus ta 
prevent their starting backward, and many have a special starting 
gear. With the exceptions above mentioned, all are made hori- 
zontal. As a rule, for the smaller sizes they indicate double, and 
for larger sizes two and a-half times their nominal horse-power. 
Thus a single cylinder 20 H.P. engine, nominal, will indicate up 
to about 50 H.P. ; a double cylinder 32 H.P. nominal will in- 
dicate 82 H.P. Messrs. Crossley also make 40 H.P. engines 
indicating 98 H.P. ; larger sizes have been described. In all 
these engines, the power obtained is based on the use of town 
gas. A special horizontal type is made for electric lighting,, 
running at 250 revolutions per minute. A drawing of it is 
shown at Fig. 37. The engine is in sizes from 6 to 14 B.H.P., 
and supplies power for 50 to 112 incandescent lamps. The 
smaller sizes up to about 4 nominal H.P. run at 200 revolutions 
per minute ; larger up to 14 H.P. nominal at 170 or 180 revolu- 
tions, and the largest motors at 1 60 revolutions per minute. 

. According to Messrs. Crossley the consumption of Manchester 
gas for driving their engines varies from 17 to 25 cubic feet- 



THE OTTO GAS ENGINE. 



91 




-a 






i 



92 



GAS EN0INB8. 



per T.H.P. per hour, in proportion to the size of the engine. 
With Dowson gas the consumption of anthracite coal is from 
1-1 lb. to 1*4 lb. per I.H.P. per hour, and of coke 1*5 lb. At 
the Crossley Works Dowson gas is used to furnish from 200 to 
300 LH.P., and no steam power is employed. 

More experiments have probably been made on the Otto ^han 
on any other gas engines. Details of these will be found in the 
table, p. 400, but a few of the more important are here sum- 
marised The earliest published trials on an Otto engine were 
carried out by MM. Brauer and Slaby, in Germany, in 1878. 
The engines indicated 3*2 H.P. and 6 H.P. ; the first ran at 
180 revolutions, the second at 159 revolutions per minute. 
Between 38 and 40 cubic feet of gas were used per I. H.P. per 
hour. This was a large consumption for an Otto engine, though 
at the time the economy, as compared with the expenditure in 
other motors, was striking. From this period for the next ten years 
the consumption of gas gradually diminished, as various improve- 
ments were effected in the engines. The amount of gas used 
also varied inversely with the size of the engine tested. In 
an important experiment* by Dr. Slaby in 1881 on a 4 H.P. 
engine, making 157 revolutions per minute, the gas consump- 
tion was 28*3 cubic feet per I.H.P. per hour. An indicator 
diagram of this trial is given at Fig. 38. Another, carried 




MTC- 



Mmoitpk^e Line 




isrc 



liarc 



Fig. 39.— Otto Engine— Indicator 
Diagram. 



Fig. 38. — Otto Engine— Indicator 
Diagram. 

out in America by Messrs. Brooks k, Steward, under Professor 
Thurston's direction (diagram Fig. 39), was on an engine 
giving 9*6 LH.P. ; the number of revolutions was 158, and the 
gas consumption per I.H.P. per hour, 24*5 cubic feet. The 
greatest economy appears to have been obtained in an engine 
tested by Garrett^ of 14*26 I.H.P, consuming 19*4 cubic feet of 
Glasgow gas per I.H.P. per hour (diagram Fig. 40). An interesting 
trial is on record, made by Teichmann k, Backing in 1887 on an 
Otto engine of 50*8 B.H.P., using Dowson gas. The consumption 
was estimated at 103 cubic feet per hour per B.H.P., equivalent 
to one quarter that quantity, say 25 cubic feet of town gas (see 

*Fall details of this experiment will be found in the Appendix to 
Profeaaor Fleeming Jenkins Paper on "Gas and Caloric Engines." 
Lecture delivered before the Institution of Civil Engineers on 21st Feb., 
1884. 



THE OTTO GAS BNGINB. 



93 



p. 404). In 1881 a series of trials were made at the Crystal 
ralace by Professor Gryll Adams, on Otto engines of varions 
powers. 

In 1888 an important set of trials of motors for electric lighting 
was made in London, under the auspices of the Society of Arts. 
The judges were Dr. Hopkinsoa, F.R.S., Professor A. Kennedy, 
F.R.S., and Mr. Beauclerk Tower, and three gas engines were 
entered for competition, an OttoCrossley, an Atkinson, and a 
Griffin. So careful and accurate a series of experiments of 
different gas engines at the same time and place, and under 
similar conditions, has not, to the writer's knowledge, been made 
before. The Otto engine was of 9 H.P. nominal, the Griffin of 
8 H.P. nominal, and the Atkinson of 6 H.P. nominal. For the 
special purpose of electric lighting, the engines were tested 
according to efficiency under the following heads: — Itegularity 
of speed under varying loads ; power of automatically varying 
the speed ; noiselessness ; cost of construction, of maintenance, 
and of fuel. All three engines worked satisfactorily. The 




M o-a t^ M •« • 7 o-t •« v-M out. rr. 



Fig. 40. — Otto Engine — ^Indicator 
Diagram. 



Fig. 41.— Otto Engine 
Diagram. 



-Indicator 



lowest consumption of gas was obtained with the Atkinson 
engine, although it was the smallest in size. Comparing the two 
other motors, the judges gave the preference to the Griffin for 
regularity of speed, and to the Otto for economy of gas and oiL 
The gas used (Gas Light and Coke Co.) was carefully analysed. 
The quantity of jacket water per hour was noted, as also its 
temperature on entering and leaving the jacket. Each of the 
engines was tested at full power, at half power, and running 
empty without load. Indicator diagrams were taken every 
quarter of an hour, and sometimes every five minutes. Fig. 41 
gives a diagram of the Otto engine taken during the trial. 

As the engines were all new, and entered for a trial competi- 
tion, they were, probably, more carefully made than usual. Hence 
the results were perhaps rather better than those obtained with 
similar types of engine, under ordinary working conditions. The 
Otto engine used was of the modem kind, with lift valves and 
tube ignition. Details of the experiments will be found in the 



94 



OAS ENGINES. 



table, but, for comparison, the chief results of the three engines 
running at full power are given below. 
The same gas was used in all the trials. 



Trials of Gas Motobs» Society of A&ts, London, September, 1888. 



Name of Engine. 


Atkinion. 


Otto^hroHley. 


Griffln- 


Diameter of cylinder. 


9*5 inches 


9-5 inches 


9-02 inches 


Length of stroke, . 


12-43 inches 


18 inches 


140 „ 


Indicated horse-power, . 


1115 


17-12 


15-47 


Brake horse-power, . 


9-48 


14-74 


12-61 


Revolutions per minute, . 
Mean effective pressure \ 
(from the diagrams), . j 


131 1 


160-1 


198*1 


4607 lbs. 


67-9 lbs. 


54-15 Iba 


Quantity of gas per LH.P. J 








per hour (exclusive of [ 
Ignition flame), . . ) 


18-82 cub. ft. 


20-55 cub. ft 


22-64 cub. ft. 








Quantity of gas per B.H.P. j 








per hour (exclusive of > 


2214 „ 


23-87 „ 


28 „ 


Ignition flame), . . ) 








Explosions per minute, . 
Inoicated horse-power for ^ 
driving engine alone, . J 


121-6 


78-4 


129 


1-67 


2-38 


2-96 


Mechanical efticiency, 


85% 


867, 


807o 


To work engine alone, . 


157o 


147o 


20*/, 


Percentage of total heat \ 
of combustion turned ( 
into work, or actual ( 
heat efliciency, . . ) 








22-8 


21-2 


21-1 








Calorific value of 1 cub. ] 








ft of gas, T.U. (from 


633 


626 


624 


chemical analysis), . ) 









The Iianchester Patent Self Starter is a simple but ingen- 
ious device for starting gas engines of any size, with or without 
compression. The apparatus consists of three small additions to 
the ordinary working parts of an engine. These are, a tube 
through which gas is forced into the cylinder, displacing the 
greater part of the air in it, and mingling with the rest to form 
an explosive charge ; a cock at the top of the cylinder, provided 
with a small automatic valve, and terminating in a nozzle open 
to the atmosphere ; and a second cam on the auxiliary shaft, to 
open the exhaust valve during the compression, as well as during 
the exhaust stroke. The latter now forms a part of many gas 
engines. 

The method of starting is as follows. — The piston being pre- 
viously stopped, or brought by hand into a position slightly over 
the incentre of the working stroke, gas is allowed to enter the 
cylinder through a special nozzle, either at the ordinary pressure 
of the gas main, or through a little hand pump. At the same 



THE OTTO GAS ENGINE. 95 

time gas is admitted through another pipe with two branches. 
One terminates in an external flame, the other communicates 
freely with the cylinder through the cock mentioned above, in 
which is an automatic valve, usually held down by its own 
weight or by a spring, and leaving the passage free. When the 
pressure in the cylinder exceeds that in the passage, the valve is 
driven up, and shuts off communication. The gas entering by 
the nozzle displaces the air in the cylinder, and forces it out 
through the f)assage until, the air being gradually expelled, gas 
follows and ignites at the external flame. The supply of gas 
being cut off, the velocity of the flame propagation exceeds that 
of the mixture issuing from the nozzle, the flame strikes back 
into the cylinder, an explosion is produced, and the piston 
driven out. The force of the explosion closes the automatic 
valve. With small engines this is sufficient to start, but in 
larger motors the second cam actuating the exhaust is brought 
into play. As the pressure in the cylinder thus falls below 
atmosphere during the compression stroke, the automatic valve 
in the passage lifts, and the mixture, admitted in the ordinary 
way, is ignited at the external flame. At the end of the stroke 
the pressure in the cylinder rises, and the flame strikes back 
into the compression Sfmce behind the piston. 

The working of this apparatus varies accoiding to the size of 
the engine. To start a large motor, a series of low-pressure 
explosions are required, until sufficient power has been gener- 
ated to drive the engine in the ordinary way. The valves, 
cocks, and the exhaust cam are then easily thrown out of gear by 
hand. The tul)e and nozzle for introducing gas into the cylinder 
may be dispensed with, and the charge admitted through the 
usual valves. The combustible mixture is then compressed as 
before into the passage leading to the external flame, ignites, 
and explodes back into the cylinder. 

One modification of the Lanchester apparatus is used to start 
the Bisschop, and another is intended for engines in which the 
mixture in the cylinder is already compressed. A double seated 
valve works in a small chamber filled with the explosive mix- 
ture, and communicating with the compression space of the 
cylinder. When the valve is on its lower seat, communication 
is cut off, and an external flame plays into the chamber; when 
the pressure in the cylinder produced by turning the crank by 
hand forces the valve on to its upper seat, the flame is cut off, 
and the ignited mixture spreads to the cylinder, and fires the 
charge. The opening of the exhaust reduces the pressure in the 
cylinder below atmosphere, the valve is again driven down on to 
its lower seat, the flame ])lays into the small auxiliary chamber, 
and a second explosion against compression is obtained. The 
force of the explosion is also sometimes used to close the valve. 



96 GAS BKOINE8. 



CHAPTER VIII. 
THE ATKINSON ENGINE. 

Contents. — Principle of Increased Expansion — Differential Engine — 
" Cycle " Engine— Link and Toggle Motion— Trials. 

The ingenious mechanism of the Otto engine described in the 
last chapter, and the fact that it was the first to realise the cycle 
of Beau de Rochas, made it long and deservedly popular. It 
seemed as if a gas en^i^ine had at last been produced, working 
with the requisite steadiness and economy. But, as time passed, 
the question arose whether a still lower gas consumption and 
better design were not possible. Experiments had proved that 
only about one-fifth of the heat given to the best Otto engine was 
utilised as power. Defective expansion was one of the chief 
causes of this loss of heat, and how to remedy it is the problem 
still occupying the minds of engineers. To increase the length 
of the piston-stroke enlarges the cylinder volume, and admits 
more of the charge, and at the same time allows gi:eater scope for 
the expansion of the gases. It is the proportion of the volume of 
admission to the total volume, or number of expansions, which 
may be altered, and the piston made to travel through a shorter 
distance when admitting and compressing, than when expanding 
the charge. The solution of the problem presented by Mr. 
Atkinson is original and ingenious. Practically, the question is 
treated from a new point of view, though the method had been 
fore-shadowed in several directions by earlier inventors, — Seraine, 
Sturgeon, and Martini — but none of them had been able to realise 
a working success. The numerous experiments made on the 
Atkinson engine prove that it is also very economical, works 
well, and requires little attention. 

Frinoiple of Atkinson Engine. — Mr. Atkinson has intro- 
duced two engines, the main principle of which is the same, 
although carried out in different ways. The whole cycle is per- 
formed in one cylinder ; there is one motor-stroke in four, and 
this stroke corresponds to one revolution of the crank only. The 
four operations of the Beau de Bochas cycle — admission, com- 
pression, explosion plus expansion, and exhaust, are effected in 
four separate strokes of different lengths, and hence the ratio of 
expansion is independent of the ratio of compression. A special 
feature of both engines is that the compression or clearance 
space varies according to the operations taking place in the 
cylinder, whether the piston be admitting, compressing, or ex- 
panding the charge. Like others who have studied the subject, 



THE ATKINSON ENGINE. 97 

Mr. Atkinson considered that the two main sources of waste of 
heat were the exhaust and the water jacket, and he has attempted 
to reduce these losses by arranging the connection between the 
piston and the crank, so as to give diiferent lengths of stroke. 
If the piston travels more quickly, there is less time for the heat 
to be carried off by the jacket ; if a longer expansion stroke is 
obtained, the heat and pressure of the gases have more time to 
act in doing useful work on the piston, before the exhaust opens. 
The more rapid and longer expansion obtained by Atkinson, 
after many trials, forms the chief novelty in his engines. He 
claims to expand the charge to the original volume during one- 
eighth of a revolution, as compared with half a revolution during 
which it is expanded in the Otto. In the latter engine the 
charge is drawn in during one out stroke of the piston, or half 
a revolution, and expanded during the next, while the crank 
makes another half revolution, to the original volume, — namely 
the total volume of the cylinder. In the Atkinson engine, the 
stroke expanding the charge is nearly double as long as that 
admitting it, and hence the charge expands to almost twice its 
original volume. In a G H.P. motor the suction or admission 
stroke is about 6} inches, the expansion stroke is about 11^ 
inches. As the whole cycle is effected during one revolution of 
the crank, this increased expansion is obtained in one-quai*ter 
revolution, and expansion to the original volume in one-eighth 
revolution, or one-quarter the time occupied in the Otto engine. 
The heat transmitted through the walls to the jacket should be in 
proportion — first, to the time the wall surfaces are exposed, and 
secondly, to the differences of temperature between them and 
the gases they enclose. Eapid and prolonged expansion ought^ 
therefore, to check the waste in both directions. The quick 
moving out of the piston brings the ignited charge in contact 
with the walls for a much shorter time, and the heat being 
absorbed in expansion, by the time the exhaust opens the 
gases are comparatively cool. Mr. Atkinson maintains that 
he utilises three times as much heat as Otto in the same 
time. It is certain that, owing to the way in which the 
lengths of the piston strokes are proportioned, more com- 
plete expansion is obtained, but whether more heat is 
really utilised than in other motors trials alone must 
decide. 

There is no slide vnlve in either of the Atkinson engines. The 
mechanism for admitting and firing the charge is simple, but 
the link and lever airangenients for connecting the piston and 
crank are a little complicated. On the whole, both his engines 
work economically, and the consumption of gns in the later 
** Cycle" engine, as shown by the Society of Arts* trials, is very 
low. The modifications introduced are— I. Initial compression 
into a much smaller space than the original volume. II. Smaller 

7 



98 



OA8 ENGINES. 



wall surface exposed in a given time. III. Bapid and continued 
expansion. 

Differential Engine. — As early as 1879 Mr. Atkinson took 
out a patent, No. 3213, for a compression engine of the Otto 
type, in which ignition was obtained by a red-hot tube. This 
was one of the first instances of a working engine firing the gas 
in this way ; the same method was employed in the same year 




Beuse. 



Fig. 42. — Atkinson's Differential Engine. 



by Leo Funck. Atkinson soon abandoned this type of con- 
struction, and began to work on new lines. Fig. 42 gives a 
sectional elevation of his first or Differential engine, exhibited 
at the Inventions Exhibition in 1885. The horizontal motor 
cylinder A contains two pistons, both working outwards, and 
joined by their connecting-rods, C, and Cj, to the bent levers, 
Fj and Fg, which act through Hj Hj upon the crank shaft 
K. Of these two pistons the left-hand one, Pj, may be called 



THE ATKINSON ENGINE. 99 

the pump piston, and chieflj compresses the charge ; the right- 
hand, Po, is the working piston, and effects the greater part of 
the working stroke, but both pistons co-operate in utilising the 
explosive force of the gases. There is only one cylinder, open 
at both ends ; during the compression of the charge the pistons 
hold the exhaust port and the ignition tube closed. 

The method of admission, ignition, discharge, and regulation 
of the speed is simple. Air is admitted through an automatic 
lift valve, gas through a valve opened by a rod from an eccentric 
on the main shaft. The rod terminates in a knife-edge acting 
on the lever of the gas valve, and if the speed be too great the 
governor, which is driven by a pulley from the crank shaft, shifts 
the valve-rod out of position, and no gas is admitted. Ignition 
is by a tube kept at a red heat by an external Bunsen burner. 
It has no valve, but opens directly to the cylinder through a 
small aperture. The exhaust, uncovered by piston Pg in its 
out stroke, is closed by an automatic valve, and opened by the 
action of the piston. The admission and distribution valves are 
in front, the exhaust is at the back of the cylinder, which has 
a water jacket at the top only, as seen in the drawing. 

The method by which the two pistons act upon the crank is 
given in the four positions at Fig. 43, showing the links, the 
levers, and the movement of the connecting-rods, p^ and ;?£ ^^ 
as before, the pump and working pistons, and h the ignition tube. 
In the first position, a, the two pistons are shown close together, 
and both at one end of the cylinder. The products of combustion 
have been completely expelled, and the clearance space between 
the pistons is reduced to its smallest limits. The energy of 
motion in the flywheel now lifts the crank, the pump piston p^ 
moves rapidly to the left, the other piston following it slowly, 
the automatic admission valves are uncovered at B, and the 
charge (position b) enters between the two pistons, through the 
openings left in the black lines in the drawing of the outline 
of the cylinder. In position c the admission valves are closed, 
the working piston has followed the pump piston rapidly to the 
further end of the cylinder, and the charge is shut into the 
diminished volume between them, leaving a relatively small 
surface of cylinder wall by which the heat can escape. A slight 
further movement of the pump piston uncovers the ignition tube, 
the compressed gases enter, the charge is fired, and the working 
piston moves rapidly out to the extreme limit of the cylinder, 
uncovering the exhaust valve. The pump piston follows more 
slowly, driving out the products of combustion (position d). 

In Fig. 43 the variable clearance space is shown, and the 
action of the pistons upon the ignition and exhaust valves. The 
clearance volume is in fact formed by the movement of the 
pistons, and communicates at a given moment with the exhaust 
or with the ignition, causing the charge to be fired or expelled. 



100 



GAS BNGIKES. 






The pistons themselves act as 
slide valves. Between them the 
functions of admission, compres- 
sion, expansion, and exhaust are 
performed in four strokes of un- 
equal lengths. The actual clear- 
ance space, into which neither 
piston enters, is about 1 inch in 
a 2 H.P. engine. The distances 
between the pistons during the 
different operations are as fol- 
lows : — Admission 3 4 inches 
(position 6), Fig. 43 ; Compres- 
sion 1 '7 inch (position c) ; ex- 
plosion and expansion 7 '6 inches 
(position d) ; exhaust 1 inch 
(position a). The proportion of 
the two strokes, or the ratio of 
admission and compression ta 
expansion and exhaust, is as 
2-58 to 4-44. 

In theory the action of the 
Differential engine appears to 
realise almost complete expan- 
sion, but the practical results 
obtained were not uniformly 
satisfactory. Professor Schott- 
ler found that the consumption 
when running empty was very 
high, and the mechanism of 
transmission was also defective. 
The levers, links, and connect- 
ing-rods were rather unwieldy, 
and after a few years' trial of 
the engine, Atkinson improved 
upon it by the production of 
the " Cycle," in which the same 
principle was retained, embodied 
in a much simpler form. 

"Cycle" Engine.— In out- 
ward appearance the " Cycle " 
engine, patent No. 3522, March 
12, 1886, seems to differ little 
from the ordinary type of a 
compression gas engine. The 
axis of the horizontal cylinder 
is placed, according to the 
usual arrangement^ at right 



THE ATKINSON ENOINB. 



101 




angles to the crank shaft, the side next the crank being open, 
and it. contains only one piston. Nevertheless, in this, as in 



102 



GAS BNQIMXS. 




THE ATKINSON ENGINE. 103 

the Differential engine, the expansion and exhaust strokes are 
longer than the admission and compression strokes, and the whole 
cjole of operations is completed during one revolution of the 
crank, with one piston and cylinder, without the aid of a pump. 
This constitutes the novelty of the " Cycle " engine. Instead 
of using two pistons, the four unequal strokes are all obtained 
with one piston, working upon the motor crank througli a 
series of rods, links, and levers, instead of acting through the 
usual connecting-rod. The admission and exhaust are operated 
with valves in the ordinary way. There is no valve to the 
ignition tube, but the charge is ignited automatically during the 
compression stroke. 

Fig. 44 gives a sectional elevation, and Fig. 45 a plan of a 
2 H.P. " Cycle " engine. A is the cylinder, P the piston, at W 
the water enters the jacket. The cylinder iis placed upon a 
strong base-plate, B, in the interior of which is the mechanism 
for transmitting power to the crank. The engine is provided 
with two flywheels. E is the lever, H the small crank or 
vibrating link, the end of which only is seen, C is the connecting- 
rod, M the lever joining H to the crank shaft K, and L the lixed 
point in the base, about which the lever E and small crank H 
oscillate. G is the ball governor, acting upon the gas admission 
valve by a lever, I, and valve-rod, v, shown in Fig. 44. As long 
as the speed is regular, the valve o opens to admit the gas. 
The rod v rests against the valve, but is not solidly connected, 
and if the speed be increased it is drawn back, the valve remains 
closed, and no gas is admitted. 

At a and b are the valves for aHmitting and discharging the 
gases, worked by two rods, m and n, and opened by the two 
cams, g and h, on either side of the crank shaft Except when 
acted upon by the cams, they are held against the end of the 
cylinder by a spring and connecting stirrup, y. Fig. 45. r is the 
cock for admitting the gas, and i the ignition tube, kept at a 
red heat by a Bunsen burner. The tube t is permanently open 
to the cylinder through a very small passage, and has no timing 
valve to uncover it at a given moment, and ignite the gases. 
The ignition of the charge in this engine is based upon the theory, 
that a small quantity of the gases of combustion always remains 
in this narrow passage. The pressure of the return stroke drives 
these gases and a portion of the fresh compressed mixture up the 
red-hot part of the tube, where they ignite, and spreading back 
into the cylinder, fire the remainder. The method works well, 
owing probably to the purity of the charge obtained by the 
long exhaust stroke, and ignition is perfectly regular. The exact 
moment of firing is determined by raising or lowering the 
chimney, and altering the position of the tube, but the time of 
ignition is not so precisely fixed in this as in most engines. 
Premature explosion during the exhaust stroke is prevented by 



104 



OA8 ENGINES. 



Xxhaiust stroke. 
I*09man a. 




A \j'0^ 



the low pressare of the gases of combustion. But whether 
ignition occurs at the inner dead point, or when the piston has 
moved out a little way, does not greatly affect the action of the 
engine. In the one case the expansion stroke is longer, in the 

other the pressure is 
yr ".^^ higher. 

. \ In these details the 

Atkinson engine differs 
little from others. Its 
distinguishing feature, 
by which practically 
complete expansion is 
said to be obtained, is 
the link and toggle 
motion shown in four 
positions at Fig. 46. 
A is the cylinder and 
P the piston as before. 
c is the connecting-rod 
to the small vibrating 
link H, which, through 
E, is joined to the fixed 
point L. Mis the lever 
connecting through the 
crank M^ to the crank 
shaft K. Position (a) 
shows the end of the 
exhaust stroke, when 
the piston is at the 
inner dead point. The 
piston moves out, 
drawing in the charge, 
and the lever M rises, 
carrying the link H 
with it At (6) the 
crank has performed 
nearly a quarter of a 
revolution, and H and 
M are in their highest 
positions. The energy 
of motion carries AI 
and M] round, forcing 
down H (position c) 
and the piston moves 
in, compressing the 
charge, but not to the 
point from whence it started. The clearance space left at the 
end of the cylinder is slightly larger than before, and the cliarge 



CompreMion 
qfehnrge, 
J*o9iHone. 





Fig. 46. — Atkinson Cycle Engine — Four posi- 
tions of Link and Toggle Motion. 



THE ATKINSON ENQINE. 



106 



is driven into it, at a pressure of about 45 lbs. The proportion 
of compression to admission is as 4 to 5. At the end of this 
stroke, when tbe crank has performed another quarter revo- 
lution, the pressure forces the gases up the red-hot tube, and 
ignition follows. The piston is driven out to the extreme limit 
of the cjlinder, M and H are both in their lowest positions (rf), 
and the crank has completed three-quarters of a revolution. The 
exhaust stroke following is longer than the expansion, since the 
piston moves in to the extreme end of the clearance space. M 
and H are raised, the crank completes its revolution, the pro- 
ducts of combustion are thoroughly discharged, and the cylinder 
cleared for the next admission-stroke. Fig. 46a shows the same 




Fig. 46a.— Atkinson Cycle Engine— 10 Positions of Crank, &c. 

arrangement for ten positions of the piston, connecting-rod, lever, 
and crank during one stroke. In the " Cycle " engine the ratio 
of the cylinder volume utilised for compression is 2-5, and for 
expansion, 4*3. The lengths of the four unequal piston strokes 
are: — First forward stroke (admission), 6-3 inches; first return 
stroke (compression), 5 03 inches ; second forward stroke (expan- 
sion), 11*13 inches; second return stroke (exhaust), 12*43 inches. 
These dimensions are for an engine of 2 H.P. nominal. 

The proportion of expansion to admission and compression 
can be varied to suit any quality of gas. By adjusting the 
centre L and link H, the engine is easily adapted for Dowson 
gas. The prolonged exhaust stroke is a source of economy. 



106 



GAS ENGINES. 



The gases are discharged at a pressure of only 10 lbs., and the 
cylinder being thoroughly cleansed after each explosion, ignition 
is said to be more certain. The usual strength of the charge is 
8 parts of air to 1 of town gas. Sometimes the dilution is 6 to 1, 
but the mixture is richer than in the Otto engine, as the charge 
is free from the products of former combustion. Experiments 
lately made by Mr. Atkinson, to determine the effect on the 

i 




Fig. 47. — Atkinson Cycle Engine — Indicator Diagram. 




Fig. 48. — Atkinson Differential Engine —Indicator Diagram. 



Ibf.lM 


.... 


-NMTP.Kbt. 


1W 






5 14« 






"• 






s 


»■' 


100 


?■ 


\^ 


•0 




% 


^ M 




- % 


40 


'—r^ 


\-N 


• 




..!..! 



00 01 0> 01 04 I 



Fig. 49. — Atkinson Cycle Engine 
— Indicator Diagram. 



IT' W"H"r-Tnr'- V-- F"?| I 

Fig. 50. — Atkinson Cycle Engine 
— Indicator Diagram. 

consumption of gas of wholly driving out, or retaining in the 
cylinder a portion of the burnt products, gave an economy of 
3 cubic feet of gas per B.H.P. per hour when the cylinder was 
thoroughly cleansed, equal to 1 1 '7 per cent, of the total consump- 
tion of gas. 

Trials. — The trials made on the Atkinson engine are given in 
the table at pp. 400, 402, 404. It has been often tested, specially 



THE ATKINSON ENGINE. 



107 




by Professors TJnwin, Schottler, and Thurston. In an important 
experiment made by Professor Unwin in 1887, the diagram of 



108 GAS ENGINES. 

which is given at Fig. 47, the consumption of London gas in the 
Atkinson engine was 22*5 cubic feet per B.H.P. per hour, and 
the ratio of expansion 3|, as compared with 2} in the Otto. 
Professor Schottler did not obtain such favourable results, but 
his engine was of the Differential type. Fig. 48 shows a 
diagram taken during the trial. The Society of Arts' experi- 
ments have been already quoted. In these the consumption of 
gas for the Atkinson engine was 19*22 cubic feet per I.H.P. 
per hour, the lowest figure recorded for any of the competing 
engines. A diagram of this trial is given at Fig. 49. One 
of the most complete tests on the Atkinson engine was made 
in October, 1891, at the TJxbridge Water Works by Mr. 
Tomlinson. In this experiment, not only the efficiency of the 
engine, but the value of the Dowson gas used to drive it, was 
determined. The engine indicated 21*95 H.P., and the anthra- 
cite burnt amounted to 1*06 lb. per I.H.P. per hour. Fig. 50 
shows a diagram taken at this trial. The best steam engines 
require about 2 lbs. of good coal per I.H.P. per hour. 

At Fig. 51 is shown a 100 H.P. nominal "Cycle" engine, 
with the cylinder slightly inclined. The drawing was kindly 
given to the author by Mr. Atkinson. 

The Atkinson engine is made by the British Gas Engine and 
Engineering Co. A type, surnamed the "Utility," has lately 
been introduced, specially for small powers and high speeds. 
The action of the engine is the same as in the " Cycle," with an 
impulse every revolution, but the cylinder is horizontal, instead 
of being inclined. The crank is enclosed, forming a reservoir, 
into which air is compressed by the action of the piston. 



CHAPTER IX. 
THE GRIFFIN, BISSCHOP, AND STOCKPORT ENGINES. 

Contents —Griffin Six-Cycle Types— Horizontal and Vertical — Trials — 
Bisschop— Method of Working — Tests — Stockport — Types. 

The Griffin Qss Engine. — This horizontal engine, constructed 
by Messrs. Dick, Kerr & Co., of Kilmarnock, has had consider- 
able success in England, especially where great steadiness and 
regularity of speed are required for electric lighting, but it is 
little known abroad. There is only one cylinder and piston. 
The engine belongs to the six-cycle type, is in a certain sense 
double-acting, and both sides of the piston are used for expansion 
of the charge, as in a steam engina It is probably the only 
motor of this special type which is still made. 



THB OBIFFINy BI88CH0P, AND STOCKPORT EKOINE8. 109 

At p. 62 will be found a description of the method of opera- 
tions in a six-cycle engine. There are six strokes of equal 
length, compnsing — 1, Admission of charge; 2, compression; 3, 
explosion and expansion ; 4, expelling products of combustion ; 
5, drawing in air or scavenger charge ; 6, expulsion of charge of 
air. The defects of this cycle are — the want of regularity in the 
speed, and the loss of power due to the small number of ignitions, 
there being only one motor stroke in six. These disadvantages 
are to a certain extent avoided in the Griffin, by making it 
double-acting. Instead of one ignition and one working impulse 
every three revolutions, a charge of pure air is admitted, and an 
ignition obtained, alternately on either side of the piston, at 
every one and a-half revolutions of the crank, and for every 
three strokes. Thus the action is much more regular, but the 
heat generated by the explosions taking place on both sides of 
the piston is almost as great as in the Lenoir engine. This is 
partly counteracted by the scavenger charge of air which, by 
cooling the cylinder, has a beneficial effect on the temperature 
of the walls. To diminish further the heat of the explosion, 
there is not only a water jacket to the cylinder barrel, but to 
the cylinder cover next the crank, through which the piston-rod 
workB. This has a cooling effect on the rod, and the indicator 
diagrams, taken during the trials of the Society of Arts, showed 
that the mean pressure in the front end of the cylinder was 
from 6 to 14 lbs. lower than at the back, where there was 
no cover jacket. The piston-rod, thus cooled, carries off part of 
the heat, and reduces the pressure. 

The following table exi)lains the double action of this engine: — 

'~' "'» ^ToFulfo™" ""^ B.ck of PUton-. «TOlu.lo».. 

Forward stroke- 1. AdmusioB^ C^L'^f^a":! ^th^^.x' 

of charge of gas ami air. l i„v i ha™t ^ ^ 

Back .trol«-2, Compresaion of f \ forward 8troke-2. Drawing in 

cnarge oi gas ana air. j y scavenger charge of pure air. 

Forward stroke— 3, Ignition and "^ 

expansion of charge of gas and 

air. 
Back stroke — 4, Discharge of 

burnt products through ex- 
haust. 
Forward stroke— 5, Drawing in\ /Back stroke — 5, Compression of 

scavenger charge of pure air. I I charj^e of gas and air. 

Back stroke — 6, Driving out V 1 rev. < Forward stroke— 6, Ignition and 

scavenger charge of pure air. i I expansion of charge of gas and 

; V air- 

The strokes forward and back, corresponding in number, as 1 - 1, occur 
simultaneously at each side of the piston. 

Some of the power generated is of course expended in 
doing negative work, or work done on the gas by the momentum. 



Back stroke — 3, Driving out 
, J scavenger charge of pure air. 

}- 1 rev. \ Forward stroke — 4, Admission 
of charge of gas and air. 



no 



GAS ENGINES. 



U 



.a 

a 

H 

a 
'E 



i 



v^m 




of the flywheel, <lec., instead of positive work of the gas on the 
engine. Although a six-cycle, by making it double-acting, it 



THE GRIFFIN ENGINR. HI 

becomes virtually what may be called a three-cycle engine. 
There are two small slide valves driven by the counter shaft, 
working the admission on each side of the piston. Through 
them the charge of pure air is also admitted and expelled. 

Fig. 52 gives a side elevation, and Fig. 53 a plan of the Griffin 
engine. Power is transmitted by the connecting-rod to the 
crank shaft K, and there are usually two flywheels. The 
counter shaft R is driven from the crank shaft by worm gearing 
D, in the proportion of 3 to 1. It revolves, therefore, once for 
every three revolutions of the crank shaft. The cylinder itself, 
closed at both ends, stands on a base or foot B, through which the 
air is drawn for the motor and scavenger charges. The slide 
valves S S^ driven by eccentrics from the counter shaft, contain 
the distributing and ignition ports ; the two exhaust valves E E^ 
worked by cams, c c^, and levers, are on the opposite side of the 
cylinder to the slide valves. In Fig. 53 the gas is admitted 
through two valves, d and (/^ controlled by the graduated cock n. 
The air enters at a a,, Fig. 52, from the base B, and the two 
mingle at the admission valves m m^ These valves are opened 
by cams on the counter shaft twice in one revolution, or every one 
and a-half revolution of the crank shaft; the gas valves dd^ open 
only once every revolution, or once for every three revolutions 
of the crank shaft. Consequently every other time the valves 
mm^ open, they admit only pure air to form the scavenger 
charge, and every other time they admit air mixed with gas 
from the valves dd^ to form the explosive charge. The gas 
admission valves are controlled by the governor G, by means of a 
cam with steps of varying width ; the quantity of gas admitted 
IS first diminished, then totally cut off, on one or both sides of 
the piston, according to the excess of speed. 

The charge of gas and air being thus admitted at either end 
of the cylinder, the slide valves S S^ worked by the eccentrics 
r rj are alteimately raised once in every revolution of the counter 
shaft, and the fresh mixture is made to communicate through 
the passages shown in Fig. 52 with the permanent burners b by 
The charge is thus fired, and the mixture explodes, driving the 
piston forward. The exhaust valves at E E^, Fig. 53, are worked 
as in the Otto, by cams, cc^, and levers passing beneath the 
cylinder. These cams on the counter shaft K open the exhaust 
first at one end, then at the other of the cylinder, every half 
revolution of the counter shaft. T Tj are the oil cups lubricating 
both sides of the cylinder. The heat and friction, generated by 
the double action, make it important to lubricate the engine 
carefully, and the oil must be pure. 

Griffin Types. — Three types of the Griffin are made, all six- 
cycle engines, but the horizontal motor here described is the 
only one which is double-acting, with one cylinder. Where it 
is possible thtis to utilise both sides of the piston, an engine may 



112 



OA8 ENGINES. 



be constructed of half the area of cylinder, and giving 
the same power at the same piston speed, as a single- 
acting motor. Professor Kennedy found, when experimenting 
on a Griffin engine, that, during a continuous run of 
six hours, the parts were not unduly heated. He was of 
opinion that space and power might in this way be econo- 
mised, but for various reasons the type has not hitherto been 
generally adopted. 

In the twin-cylinder Griffin engine, used for electric lighting, 
where great regularity of working is required, there are two 
horizontal cylinders side by side, each single-acting, and having 
one motor stroke in six. The cranks of the pistons work in the 
same plane at ISC', and an explosion is obtained every three 
revolutions from each cylinder, or for every one and a half 




0-7 Oiiticft, 



Fig. 54. — Griffin Engine— Indicator Diagram. 

revolutions of the crank shaft. The action is similar to that of 
the double-acting engine, except that the operations, instead of 
taking place in one cylinder, alternately, on either side of the 
piston, are carried out in the two cylinders, on one side only 
of the piston. The whole cycle of operations is gone through 
in each cylinder, and the charge is admitted, compressed, ignited, 
expanded, and driven out, and the scavenger charge of air 
introduced and exhausted. In the one cylinder the cycle is 
three strokes in advance of the other. The forward motor 
stroke of one piston corresponds with the expulsion of the 
scavenger charge of air in the other, and admission in one 
cylinder with exhaust in the other. 

The third type of this engine, for small powers, is made 
vertical. It is single-acting, and hence there is only one ex- 
plosion and one motor stroke for every three revolutions of the- 



THE QBIFFIN AND BI88CH0P ENGINES. 



113 



crank, or one working stroke in six. Considerable speed is 
therefore necessary to give the power, and the engine runs at 
about 200 revolutions per minute. The general construction 
and the cycle of operations are the same as in the other types, 
but the parts are not in duplicate, and there is only one gas 
admission and exhaust valve. This engine is made in sizes up 
to 6 H.P. nominal, but is little used except for very small 
|X>wers. It is handy and compact and runs quietly, but not 
with the same regularity as the double-acting engine. The 
scavenger charge of air tends to cool the walls, and diminishes 
the amount of water required for the jacket, and there is less 
heat to counteract than in four-cycle engines. 

Three important trials have been made upon the Griffin 
engine, the first by Professor Jamieson, the second by Professor 
Kennedy, F.R.S., both at Kilmarnock, the third at the Society 
of Arts' trial competitions in 1888. In Professor Kennedy's 
trial an engine was tested of 14*94 B.H.P. with 23 cubic feet 
of gas consumed per brake H.P. per hour. The indicator dia- 
gram of this trial is shown at Fig. 54. At the trials of the 
Society of Arts (diagram Fig. 55), 
the engine indicated 15*47 H.P., 
and the results were not so 
favourable. The gas used 
amounted to 23 cubic feet per 
I. H.P. and 28 cubic feet per 
B.H.P. per hour. Part of the 
increased expenditure of gas was 
probably due to the rather 
smaller size of the engine. 
Most gas motors, other condi- 
tions being equal, vary in con- 
sumption of gas inversely in 
proportion to the H.P. de- 




%0 Ot oi 0-8 0-4 0-6 0-9 (htOt^If 



Fig. 56.— Griffin Engine— 
Indicator Diagram. 



veloped. It should be remembered that the heating value of 
London, as compared with Scotch gas, is also much lower, and 
this affected the results. The Griffin engine at the Society of 
Arts' trial was especially commended for steadiness of speed and 
regularity. 

BisBOhop. — ^The Bisschop engine presents another example 
of a special type, and cannot be classified under any of the regular 
divisions of gas motors. Brought out for very small powers by 
Alexis de Bisschop in 1870-72, it can scarcely be called a modern 
engine, though it is still made. It appeared about four years 
after the Otto and Langen non-compression atmospheric engine, 
and was intended especially to avoid the noise and recoil of the 
free piston, rack and clutch gear, and the other defects of that 
motor. It belongs to what is called a mixed typa The charge 
of gas and air is admitted at atmospheric pressure, and the force 

8 



114 GAS ENGINES. 

of the explosion drives up the piston, hut it is attached in a special 
way to the crank, and does not run free. The pressure of the 
atmosphere, and the energy stored up in the flywheel, then drive 
down the piston into the vacuum formed below by the cooling 
of the gases. The action of the walls is here partly turned to 
good account, reduces the temperature of the exhaust gases, 
and helps to form the vacuum. In a certain sense the Bisschop, 
like other atmospheric engines, may be called double-acting, the 
force of the explosion being used on one side of the piston, and 
the pressure of the atmosphere on the other. With the excep- 
tion of a few small French motors, it is probably the only non- 
compressing engine still in the market. Although originally 
brought out in France, it has had more success in England, and 
is practically a British engine. It is said that about 2,000 
motors have been sold in this country. 

Like all non-compressing engines, the Bisschop is not very 
economical, and this may be the reason why it is no longer in 
favour on the Continent, where the high price of gas makes 
economy in a gas engine of so much importance. Many cases occur, 
however, where simplicity and ease in starting and in handling 
are more necessary, and here the Bisschop, which is a most con- 
venient little motor, has been found of use for very small powers. 
The English makers are Messrs. Andrew of Stockport. 

The engine has a vertical cylinder closed at both ends, and 
the piston-rod works in an upright hollow column. Above is a 
crosshead from which the connecting-rod, working direct through 
the crank on to the motor shaft, hangs parallel to the piston-rod 
during the up stroke. All these parts are close to the high 
column carrying the piston and rod, and this causes a good deal 
of vibration, but the impulse from the piston to the crank is 
direct. Explosion occurs immediately after the piston has passed 
over the lower dead point. The shock forces up the piston 
rapidly, the crank is carried round through more than half a 
revolution, and the connecting-rod brought parallel with the 
piston-rod inside the column. Thus expansion is exceedingly 
rapid, and proportionally greater than admission. The dis- 
tribution of the gas and air, and the discharge of the exhaust 
gases, are effected by a trunk piston valve, driven from an eccen- 
tric on the crank shaft. Gas and air are first admitted through 
valves covered with thin rubber discs; the air valve is perforated 
with 18, and the gas valve with 3 holes, admitting the charge 
in the proportion of 6 parts of air to 1 of gas. The piston valve 
is then driven down, and brought into line with the distributing 
chamber, and the corresponding admission port of the cylinder. 
Cold air is also sometimes admitted into the ports at the begin- 
.ning of the up stroke, to cool the products of combustion. 

The engine has no water jacket, the cylinder being provided 
externally with ribs, to cool the metal. Strange to say, it not 



THB BI880H0P ENGINE. 



116 



only works without oiling, but the manufacturers expressly 
stipulate that neither the piston nor the other parts shall be 
lubricated. A few drops of oil are applied occasionally to the 
crosshead and the motor crank only. Ignition is obtained by an 
external flame. 

Fig. 56 gives a sectional elevation of the Bisschop engine, and 
Fig. 57 a section of the piston valve. The parts are lettered 
alike in the two drawings ; the piston valve admits, distributes, 
and expels the charge. A is the motor cylinder and F the 




Fig. 56.— Bisschop Engine— 
Sectional Elevation. 



Fig. 67. — Bisschop Engine— Section 
of Piston Valve. 



piston, c is the connecting-rod and C the crank, K the crank 
shaft. G is the crosshead, and r the piston-rod working in it. 
In Fig. 56 the piston is half way through the up-stroke. The 
eccentric e on the crank shaft drives the piston valve p (Fig. 57) 
through lever L The exhaust is seen at £; A; is the small open- 
ing about half way up the cylinder, covered by a flap valve ; an 
external flame burns behind it at n, and at o is a second auxiliary 
flame, to rekindle the other when blown out. Fig. 57 shows the 
air valve with the holes for regulating the supply, and the action 
of the piston valve p ; the gas enters at t (Fig. 56). 

Method of Working. — Beginning with the piston in its* 
lowest position, when the exhaust has just been cut off", the 
pressure in the cylinder being below atmosphere, gas and air enter 



126 OA8 ENGINES. 

stroke. The exhaust is now opened by levers T, the motor 
piston beginning the return stroke, drives out the gases of com- 
bustion, and the compressed charge entering from the pump j 
through the piston valve, assists to expel them. The return ( 
movement of P closes the exhaust. Communication between | 
the two cylinders is kept open by the valve, while the air 
and gas admission are held closed, and both pistons compress , 
the charge into the combustion chamber R. The pump piston 
completes the in stroke first, and the ports of communication 
between the two cylinders are closed by the movement of the 
valve. While the motor still further compresses the charge, 
the pump and valve pistons begin their out stroke, and the 
passage in the valve is brought to face the cylinder port L and 
the ignition tube I. The gases are ignited, and drive out the 
motor piston, doing useful work. A fresh charge has already 
been admitted behind D, through the ports of the valve, and 
the cycle recommences. 

Experiments were carried out at Liverpool on a 6 H.P, nomi- 
nal Fawcett engine by Mr. T. L. Miller, in February, 1890. 
The heating value of Liverpool gas was found to be rather 
high. The number of revolutions was 150*8 per minute, the 
engine indicated 11-49 H.P., and 8*52 B.H.P. The mean con- 
sumption of gas was 18'4 cubic feet per I.H.P. per hour, and 
24*74 cubic feet per B.H.P. per hour, excluding the gas used to 
heat the ignition tube. The mechanical efficiency was rather 
low, viz., 74 per cent. See Table of Trials, p. 402. 

Acme. — The Acm6 engine, patented by Messrs. Alexander, 
Burt <k Co., of Glasgow, who were formerly makers of the Ajax, 
shows a novel attempt to solve the problem, how to increase 
expansion of the explosive gases in proportion to admission and 
compression. In this engine there are two horizontal cylinders, 
two pistons, and two crank shafts connected by spur wheels in 
the proportion of two to one. The cylinders are alongside each 
other, and the one is shorter and smaller than the other. While 
the piston of the larger cylinder makes one stroke, the piston of 
the smaller makes two, one crank and shaft run, therefore, at 
half as many revolutions as the other. The cylinder volumes 
and lengths of stroke also differ, and the cranks being at different 
angles, the pistons do not work together. When the first or 
larger piston has completed the in or the out stroke, the smaller 
second piston is about 45** behind. The expansion obtained by 
using two cylinders and pistons is said to be so complete that 
the gases, when discharged, are comparatively cool, and the 
exhaust noiseless. The cycle of operations is divided between 
the two cylinders. Hot tube ignition without a timing valve, 
and discharge of the gases of combustion, both take place in the 
smaller cylinder, the piston of which uncovers these openings 
near the beginning and end of its out stroke. The firing of the 



OTHER BRITISH OAS ENGINES. 127 

charge and the exhaust are timed to occur when the first piston 
is at positions corresponding to the inner and outer dead points. 
In other respects the engine presents no new features. There 
are two flywheels, one automatic lift valve admits the gas and 
air, and the rod opening it is connected to a pendulum weight 
governor. An Acm6 engine was shown at the Crystal Palace 
Electrical Exhibition (1892), and was somewhat noisy in action. 
Beginning with the exhaust in both cylinders, the following is 
the cycle of operations. The first piston being at its inner dead 
pointy the first cylinder is completely cleared of the products of 
the former charge, which are passing out through the exhaust 
port in the second cylinder. Meanwhile the second piston has 
began its return stroke, and discharged the unburnt gases 
through the exhaust ports uncovered during the out stroke. 
As soon as the first piston is conjpletely in, the second 
piston returning, and the volume in both cylinders proportion- 
ally reduced; admission commences. The first piston draws in a 
fresh charge, which is at the same time compressed by the slower 
in stroke of the second piston, as it passes the dead point. When 
the first piston is fully, and the second partly out, admission is 
complete. The first piston then moves in, compressing the 
charge ; the second piston also compresses till the ignition port 
is reached, and explosion follows. At the moment when the 
charge is fired, the gases are compressed into little more than 
the clearance spaces. The explosion drives out both pistons, the 
first to its farthest limit, the second through part of its stroke, 
till it reaches and uncovers the exhaust ports. Thus the largest 
volume in both cylinders is utilised for the expansion stroke. 
The first piston makes the in stroke, the second completes the 
out stroke and returns in, covering the exhaust port, and the 
cycle is repeated. 

Several sizes of the Acm^ engine were tested, both with full 
load on and running light, by Professor W. T. Rowden, of Ander- 
son's College, Glasgow. In 1888 and 1889 he experimented 
upon engines of 2 H.P. nominal, running at 170 revolutions per 
minute. In the first engine the B.H.P. was 3*16 and the con- 
sumption of gas 24*4 cubic feet per B.H.P. per hour. In the 
later and improved engine, a trial made with full power gave 
3 '14 B.H.P., and a corresponding consumption of 18*1 cubic feet 
of gas per hour. Professor Rowden made experiments in 
December, 1890, on a larger engine of 6 H.P. nominal, where 
the B.H.P. was 8-28, and gas consumption 17-3 cubic feet per 
B.H.P. per hour. In a further trial of the same engine the 
B.H.P. was 7*8, and the gas consumption as low as 16-83 cubic 
feet per B.H.P. per hour. These trials compare favourably with 
the standard gas engine trials of the Society of Arts, and the 
value of the results is enhanced by the fact that the engines 
tested were not especially adapted to the purposes of the trial, 



128 GA8 ENGINES. 

but ran under ordinary working conditions. Allowance must be 
made for the richer quality of Glasgow as compared with London 
gas ; 9 cubic feet of the first is computed to give the same heat- 
ing power as 10 cubic feet of the second. 

Fielding. — The Fielding engine, made by Messrs. Fielding 
and Piatt, of Gloucester, is constructed on the principles of the 
Otto, and has the same cycle ; the slide valve gear is abolished, 
and the parts are simple. There is hot tube ignition, but no 
timing valve. A timiog valve is constructed to open the port 
leading to the hot ignition tube, at the exact moment when an 
explosion is required. Punctual ignition is a necessary feature 
of all gas engine cycles. Some inventors, however, have suc- 
ceeded in dispensing with the timing valve, and .they maintain 
that, by varying the length of the ignition tube, and the 
distance from tlie red-hot metal to the motor cylinder, accurate 
ignition can be obtained. The gases do not reach this heated 
part of the tube until the end of the in stroke, when compression 
is greatest. Ignition at the dead point has been one of the main 
features of the gas engine theory since the time of Beau de 
Rochas, and it may be doubted whether it is really so easily 
obtained as these inventors assert. The practice of dispensing 
with the timing valve is sanctioned by no less an authority 
than Mr. Atkinson. 

In the Fielding and Piatt engine the organs of distribution 
and exhaust, and the oiling apparatus, are driven, as in the Otto, 
from a side shaft worked by worm gear from the main shaft. 
The valves are opened by cams. Another cam actuates the 
governor, which is simply a small dash pot, with a piston 
connected to a lever opening the gas valve. If the speed be too 
great, the dash pot cannot overtake the motion of the engine, 
and is left behind ; it drags back the piston, raises the lever, and 
the gas valve remains closed. Several large sizes of this engine 
were exhibited at the Royal Agricultural Society's show at 
Doncaster in 1891, when it was brought to public notice for the 
first time. The makers claim a gas consumption of 17 to 26 
cubic feet per I.H.P. per hour, according to the size of the 
engine, and quality of gas used. A small vertical 1 H.P. type, 
resembling the Otto domestic motor, has been introduced by 
this firm for household use. 

A well designed horizontal type of motor indicating 100 H.P. 
has also lately been brought out. There is one ''mitre-seated 
valve" for admitting the charge, and expelling the burnt products. 
A piston valve, driven by an eccentric on the crank shaft, opens 
communication between the inlet and exhaust cylinder ports 
and this valve, the rod of which is worked by a cam. Ignition 
is by hot tube, and there is in this engine a timing valve, acted 
on by the same eccentric as the piston valve. All these organs 
are contained in a valve chest at the side of the motor cylinder. 



OTHER BRITISH GAS ENGINES. 129 

This engine is also provided with a special starting gear, 
consisting; of a reservoir, into which air is compressed by the 
action of the piston. To start the engine the cylinder is first 
filled with gas, and the supply cocks being closed, the compressed 
air is then allowed to enter. This method is said to be powerful 
enough to start an engine with partial load on. The engine has 
a ball governor, and runs at 160 revolutions per minute. It is 
illustrated in Engineering, January 27, 1893. 

Forward. — The Forward gas engine, made by Messrs. 
Barker & Co., of Birmingham, in sizes from j H.P. to 50 H.P. is 
really a "simplified Otto." The Beau de Rochas cycle is used, 
but several improvements are added. There is no admission 
slide valve, and ignition is by a hot tube, as in most modem 
English gas engines. The chief novelty is the device used to 
obtain punctual ignition of the charge, without a timing valve. 
The opening of the ignition tube is covered by a rotating disc, 
with "hit and miss" slots; the surface of the disc is divided into 
radiating sections, alternately pierced and solid, which, as the 
disc revolves, are brought successively across the ignition port. 
According to the section of the disc facing it, the ignition port 
communicates with, or is shut off from, the cylinder. This 
arrangement is found in several foreign engines, and is not 
altogether new. In some of the Forward engines a ball governor, 
in others a momentum governor, is used. The governing gear is 
arranged to regulate the speed of the engine in three different 
ways. It controls the admission of the charge of gas and air into 
the combustion chamber, and at the same time the rotatory 
motion of the disc. Unless there is a charge in the chamber, the 
disc cannot open the ignition port, nor can the charge pass into 
the chamber, unless an open slot faces the ignition port. Lastly, 
the governor acts upon the supply of gas, and cuts it off altogether, 
should the speed increase greatly beyond the normal limits. The 
same cylinder port serves for the admission of the charge and the 
exhaust. By this arrangement the port is said to be kept cool, 
and the waste of mixed gases prevented. The rotating disc is 
found far less liable to become heated than a slide valve. 

Careful tests have been made on the Forward engine by 
Professor Robert Smith, of Mason College, Birmingham, and by 
Mr. Holroyd-Sroith. Both these experts have reported favour- 
ably, pronouncing it a good engine, with all the advantages and 
few of the defects of the Otto. During trials of several hours' 
duration, the engine ran very steadily, and was found to work 
well, even under the severe test of counting the number of 
revolutions every ten seconds, instead of every minute, and 
varying the weight on the brake as rapidly as possible. The real 
test of regular working in an engine is absence of fluctuations in 
the speed, when the load is suddenly put on or taken off, as in 
electric installations. In a test made by Professor R. Qmitb 

9 



130 GAS ENGINES. 

with full working load, the speed was 176-86 revolutions per 
minute, and the explosions 59 or 1 for every 3 revolutions. In 
another at half load the number of revolutions was 177, with 
67 '8 explosions per minute, or 3*06 revolutions per explosion. 
The consumption of gas per I.H.P. per hour was slightly less 
than in the Otto engine. In the first trial it was 2079 cubic 
feet of Birmingham gas per I.H.P. per hour, and 23*97 per B.H.P. 
per hour. Nearly all the tests made under ordinary working 
conditions give a little over 20 cubic feet of gas per I.H.P. per 
hour, or about the same as the Otto. The mechanical efficiency 
of the engine was 86 per cent., and it was timed to run up to 
210 revolutions per minute. See Table of Trials, p. 402. 

Of the numerous gas motors lately brought out in England, 
many are made almost exclusively for small powers. These little 
engines do not vary much in type ; their main recommendation 
is not so much economy of gas, but lightness and simplicity, 
and the ease with which they are started and worked. In many 
industrial operations, the use of small gas motors often makes 
the difference between a profit or a loss to the employer, parti- 
cularly with the difficulties of modem labour. 

Midland. — It is a peculiarity of the Midland engine, manu- 
factured by Messrs. John Taylor of Nottingham, that, although 
especially intended for small powers and domestic purposes, it 
has two cylinders, motor and pump. Both are single acting, 
fixed on the same frame, and occupy little more space than 
the single cylinder of the ordinary type, and all the other 
parts are simple. The smaller sizes are vertical, the larger 
engines up to 9 H.P. are horizontal, and adapted for driving 
with Dowson gas. In the vertical engines the two cylinders 
are placed side by side, and the pistons work on the same 
main shaft, by means of two connecting-rods and two cranks. 
In the pump the charge is admitted and compressed, in the 
motor it is exploded, expanded, and discharged, and thus an 
explosion every revolution is obtained. As the crank of the 
motor piston is set at a different angle to that of the pump, 
compression is ended, and the charge begins to enter, and to 
drive out before it the products of combustion in the working 
cylinder, before the motor piston has quite completed the down 
stroke. There are no slide valves, cams, or cog wheels, and 
no counter shaft is necessary, as there is an explosion every 
revolution. The admission valves are driven by a single ec- 
centric and i*od on the crank shafb, and opened once in every 
revolution, and the gas valve is acted upon by a centrifugal 
governor, and lifted or closed according to the speed. Ignition 
is by a hot tube heated by a Bunsen burner, and there is no 
timing valve ; the length of the tube determines the exact 
moment of ignition. The upper portion alone is kept at a red 
heat. The compressed gases are driven into the lower end of 



OTHER BRITISH GAS ENGINES. 131 

the tube by the down stroke of the compressing piston, and 
ignite only when the maximum pressure is reached, and they 
are forced into the upper part. There is no exhaust valve ; the 
gases are discharged silently through a chamber in the base. 
The gas consumption is small, and the engine requires little 
lubrication or attention, because the parts are few and simple. 
Owing to the two cylinders and the explosions obtained every 
revolution, it is said to give more power for the same expen- 
diture of gas than any other of equal size. A later single- 
•cylinder horizontal type has been introduced, in which the 
admission of the charge is effected by a rod and lever, and a 
small crank worked from the main shaft by worm gearing. The 
exhaust is driven by an eccentric on the same shaft. The 
supply of gas is regulated by a patent gas bag, and is controlled 
by an inertia governor. A drawing is given in The Engiiieering 
Seview, August 5, 1891. 

Express. — The Express, made by Messrs. Furnival & Oo., of 
Reddish, near Stockport, is another single cylinder gas engine 
which has appeared since the expiration of the Otto patent. In 
design, construction, and cycle of operations, it closely resembles 
that engine. Admission is by ordinary lift valves, and hot tube 
ignition is used. The side shaft is driven in the usual way by 
worm gear from the main shaft, and a centrifugal governor acts 
-on the gas valve. The engine is made in sizes up to about 9 H.P. 

Dougill. — The Dougill is a single-cylinder horizontal engine, 
using the four-cycle, and made by Messrs. Hindle & Norton, of 
Oldham, in sizes up to 5 H.P. The larger sizes only have a 
water jacket; in the smaller, the outer surface of the cylinder is 
provided with ribs, to carry off the heat. The engine is simple 
and has no slide or ignition timing valve ; admission is through 
mushroom seated valves, worked by cams and levers from the 
•crank shaft. Two novelties are described in the specification. 
The inventor claims so to time the lifting of the gas and air ad- 
mission valves, that air only is admitted at the beginning and 
-end, and gas and air in proper proportions during the middle of 
the admission stroke. According to Mr. Dougili's theory, the 
residuum of unburnt gases already in the cylinder combines 
with the air, and forms a cool, non-combustible '* envelope" round 
the rich charge. He endeavours to add to this effect^ and to 
increase the force of the explosion, by injecting the gas through 
4L small pipe into the centre of the cylinder. He maintains that 
only the inflammable charge in the middle ignites, the sur- 
rounding gases do not burn, but take up the heat of explosion 
in expansion, and help to drive the piston forward, doing useful 
work. Thus the greater part of the heat is said to be utilised, 
instead of being carried off by the water jacket. It is doubtful 
whether the gases are really stratified, and preserve the position 
indicated by the inventor. The ignition tube is at the side of 



132 6A8 ENGINES. 

the cylinder, and the upper portion alone is at a red heat. A 
small side chamber, the size of which is determined by a movable 
plug, regulates the pressure of the gases. This chamber is the 
second novel feature in the engine. The mouth of the hot tube 
is always open, but the final pressure at the end of the return 
stroke is required, to drive the gases into the glowing upper 
portion. Gas from the pipe is admitted to the tube at a lower 
pressure when starting the engine. 

Trent. — In the Trent horizontal engine, made by the Company 
of that name at Nottingham, the cycle of operations differs from 
the Otto in several respects. An impulse is obtained at every 
revolution by means of a differential piston, several varieties of 
which have been already described. The use of this compound 
piston always renders an auxiliary chamber necessary, which in 
this motor serves for explosion as well as compression. There 
is no slide valve, and the valves are of the ordinary lift type. 
Although externally not differing from other gas engines, the 
motor is really compound, and consists of two cylinders tandem, 
both water jacketed. There are two pistons of slightly differ- 
ent diameters ; both work on to the same connecting-rod and 
crank. "When fully in, the pistons fit the cylinders exactly, but 
as they move out an annular space is uncovered in the larger 
cylinder, as the smaller piston passes before it. Into this 
annular space the charge is first drawn. The valve admitting 
the gas and air, worked from an eccentric on the main shaft, ia 
praised as the pistons are driven forward by the force of the 
explosion. The return stroke closes the admission valve, and 
compresses the gas and air through another valve into the 
explosion chamber at the side of the smaller cylinder, in which 
is the hot ignition tube. The compressed charge drives out 
gases left from the previous combustion through the exhaust 
lift valve, which is worked by cams from a side shaft in the 
usual way. The ignition tube is at the mouth of the explo- 
sion chamber, at the crank end of the cylinders, and as soon 
as the exhaust gases have been driven out, and the pressure 
of the charge is at its maximum, a small valve opening into 
the tube is raised. The charge is fired, fills the explosion 
chamber, and enters the motor cylinder at the back of the 
smaller piston. Both pistons are driven out, a fresh charge is 
drawn into the annular space, and again compressed into th& 
explosion chamber. 

In this engine ignition is effected at constant pressure, instead 
of at constant volume. The motor piston moves out gradually 
under the steady pressure of the flame, instead of remaining 
practically stationary while an explosion takes place behind it, 
and drives it out. This is the cycle used in the Simon engine 
and a few others, and is much recommended by many authorities. 
The explosion occurs in a separate chamber, apart from the motor 



OTHER BRITISH OAS ENGINES. 133 

cylinder, and the piston is, therefore, not much affected by the 
heat, and wears better. The discharge of the exhaust gases is 
also carried out in this chamber, and only admission and expansion 
of the charge take place in the compound motor cylinder. All 
the organs of admission, distribution, and ignition are at the 
crank, instead of at the further end of the cylinder. A centri- 
fugal governor acts on the gas admission valve, and is very 
sensitive. In engines having an impulse at every revolution, 
lower pressures and lower speeds can be used than where a 
motor impulse is only given every two strokes, and a corre- 
sponding diminution in wear and in friction is obtained. The 
Trent engine is said to be very easily started. The consumption 
of gas is also low. Tests made of a nominal 4 H.P. engine, 
indicating 10*2 H.P., gave a consumption of less than 18 cubic 
feet per I. H.P. per hour. For a small power engine, these results 
are noteworthy. See drawings in Engineering , June 26, 1891. 

Bobson's Shipley. — Mr. John Robson, of Shipley, makes a 
small single-cylinder type termed the " Nonpareil " or Shipley, 
constructed on the same principles, and using the same cycle as 
the Otto. Ordinary lift valves and hot tube ignition are em- 
ployed, and the engines are made horizontal for larger, vertical 
for smaller powers. The gas, admission, and exhaust valves are 
worked by cams on the side shaft, geared to the main shaft in 
the usual proportion, and there is no timing valve. No special 
feature in this engine requires description. 

Trusty, Premier. — The "Trusty" horizontal engine, by W ey- 
man<!^Oo., of Guildford, and the "Premier," made vertical and 
horizontal by Messrs. Wells, of Sandiacre, near Nottingham, are 
both single cylinder engines, using the four-cycle, like the Shipley, 
and having an explosion every two revolutions. The valves of 
the Trusty are worked by a side shaft gearing into the crank 
shaft ; the Premier is driven in the same manner. Both engines 
have hot ignition tubes without a timing valve, and run at 160 
to 180 revolutions per minute. An inertia governor is employed 
in the Wells engine. It consists of a bar with a weight at one 
end, and a notched jaw at the other, attached to the lever open- 
ing the gas valve. Above the bar is a disc rotating at the same 
speed as the engine. Each time the disc completes a circuit, a 
pin upon it is brought round to the jaw, and entering it, pushes 
down the bar, and opens the gas valve. But if the disc rotate at 
too great a speed, the pin upon it slips past the jaw, and no gas 
is admitted. The Trusty, the Shipley, and the Premier engines 
were exhibited at the Agricultural Show at Doncaster, in June, 
1891. None of them seem to be made in sizes exceeding 
about 12 H.P. 

19'ational. — The "National" horizontal single-cylinder engine, 
made at Ashton-under-Lyne, is again a repetition of the Otto, 
with hot tube ignition, and lift valves worked from a side shaft. 



134 OAS ENGINES. 

It is made in sizes up to 50 I.H.P. In all these engines, the, 
simple construction of the valves is said to effect a considerable 
saving in the consumption of oil. 

Palatine. — The Palatine Engineering Company, Liverpool, 
have introduced a vertical engine designed on a different prin- 
ciple to the ordinary type. The crank shaft and connecting-rod. 
are enclosed in a hollow cast-iron chamber above the cylinder, 
into which the upper part of the piston is used to compress air«. 
As soon as tlie exhaust opens, at the termination of the working 
or up stroke, the piston uncovers two ports in the cylinder wall, 
through which the compressed air enters, driving before it the 
exhaust gases, cooling the cylinder, and cleansing it of the pro- 
ducts of the former charge. More perfect combustion is said to 
be obtained, as the purity of the incoming charge is not diluted 
by the unburnt gases from the previous explosion. The effect is 
apparently similar to that of the compressed air introduced ia^ 
the German Benz and Daimler engines ; a weaker mixture than 
usual can be employed, and the consumption of gas thus econo-. 
mised. The gas enters the cylinder from a small pump, the. 
piston of which is worked by wheels from the main shaft, and 
delivers 9, certain quantity per stroke in proportion to the air 
admitted; the amount is regulated by a centrifugal governor. 
The engine runs at from 200 to 350 revolutions per minute. 
Hot tube ignition is used, the valve to fire the charge being 
worked by a rod from the crank shaft. The principle of the- 
Palatine engine, although not quite novel, is ingenious, and 
expansion is probably greater than in motors of the four-cycle- 
type. To utilise the upper surface of the piston to compress the 
air above it is undoubtedly an advantage, and the crank being 
covered in makes the engine more convenient for use in con- 
fined spaces. It is made in sizes of 5 and 6 H.P. 

Robey. — The Robey horizontal engine is manufactured by 
Messrs. Robey & Co., of Lincoln (Richardson <& Norris patents), 
for driving dynamos for electric lighting, and other purposes.- 
It has heavy flywheels, and the ball governor, as usual with this 
class of motor, is extremely sensitive ; it acts on the gas valve 
by means of a lever and small roller.- The usual four-cycle is 
employed. Ignition is by a tube heated by a Bunsen burner, a 
double-headed valve with two seats is used to fire the charge, 
and great accuracy of ignition is obtained. In the latest 
engines there is no timing valve. The number of revolutions 
can be readily altered, and the engine made to run, if re- 
quired, at low speed during the day, and at a high speed at 
night. A patent " safety combination " is provided to prevent 
starting backwards, and by altering the eccentric lever the 
motion of the engine can be reversed. Coming from so well 
known a firm, this motor will probably be successful. It is well 
designed and constructed, and is already made in various sizes. 



OTHER BRITISH GAS ENGINES. 135 

Two types, chiefly horizontal, are used. The first, in sizes from 
2 to 86 B.H.P., runs at 160 to 230 revolutions per minute; 
the second, intended for electric lighting, is from 9 to 27 B.H.P., 
and the speed varies from 200 to. 230 revolutions per minute. 
According to the makers, the cost of working these engines is Id, 
per H.P. per hour. Drawings are given in The Engineer j 
October 14, 1892. 

Various Engines.-T^Other motors employing the four-cycle, 
and generally resembling the Otto, with hot tube ignition and 
lift valves, are Woodhead's ** Leeds," a vertical gas engine, the 
",Bradford" (horizontal), brought out. by S. Clayton & Co. in 
1882, and claiming to be one of the first engines using hot tube 
ignition without a timing valve ; and the Purnell, a modifica- 
tion of the Turner, made at the Atlas Works, Blackfriars. The 
Capitaine, a vertical motor, having the cylinder with the ignition, 
admission, and governing valves above the crank, has been intro- 
duced from abroad, and a description will be found in the 
German section. In all these small engines, economy in the 
consumption of gas is not so much considered as solidity, com- 
pactness, and simplicity. No trials by independent experts 
have yet been made upon them. 

, Day. — Among modern English engines for small powers, one 
of the most simple and ingenious is constructed by Messrs. 
Day k Co., of Bath. In this little vertical motor several varia- 
tions from the ordinary gas engine cycle have been intro- 
duced, and although most of them have appeared in other 
engines, they are here utilised in a new and original way. 
With one cylinder only, an explosion is obtained at every 
revolution. The cylinder and piston are at the top, and the 
latter works downwards upon the crank through a connecting 
rpd. Instead of a pump, a reservoir is formed by enclosing 
the crank in an air-tight chamber, and through a channel or 
passage at the side the mixture is forced from it into the upper 
part of the cylinder. With the exception of this reservoir 
and charging passage, the mechanism of the engine is very 
simple. There is no counter shaft or eccentric, the action 
of the piston itself causing the admission and discharge of the 
gases. There is only one valve, through which the gas and air 
are automatically admitted, in proper proportions, by the suction 
of the up stroke of the piston. The exhaust gases are discharged 
through an opening in the cylinder, uncovered by the piston 
during the down stroke ; ignition is by a hot tube without a 
timing valve, placed at the top of the cylinder. As there is an 
explosion every revolution, there is no danger of premature 
ignition, the gases being driven into the hot tube at every up 
stroke by the compressing action of the piston. 

Fig. 62 gives a sectional elevation of a Day small -power 
engine, a is the hot ignition tube, and h the automatic valve 



136 



OAS ENGINES. 



T^jiM 



for the admission of gas and air, d is the chamber enclosing the 
crank, into which the charge from h is first drawn. At e is the 
exhaust, which is merely an opening half-way down the cylinder, 
uncovered by the piston ; / is the channel connecting the crank 
chamber with the working part of the cylinder. All the four 
operations of the Beau de Rochas cycle — admission, compression, 
explosion plus expansion, and exhaust, are performed in one 
down and one up stroke of the piston, the clown being the 
motor stroke. The action of the engine is as follows :— The 
crank being at the lower dead point, 
and the trunk piston at the bottom of 
the cylinder, its edges just clear the 
port opening from the channel y in the 
side into the upper end of the cylinder. 
Through this channel, during the latter 
part of the down stroke, the fresh 
charge, forced out by the piston, has 
been passing from the reservoir rf. 
The up stroke now begins, and the 
port above /is immediately closed; the 
upper face of the piston compresses the 
gas and air above it, and drives them 
up the ignition tube, a. Meanwhile, 
the reservoir having been emptied of 
its contents through the side channel, 
a partial vacuum is formed below the 
piston ; the automatic valve h is lifted, 
and a fresh charge enters and fills the 
reservoir, d. The piston having reached 
the end of the up stroke, the charge is 
fired, and the expansion drives it down ; 
the exhaust port is uncovered and the 
gases discharged. When the piston has 
passed through half its stroke, it begins to force the fresh charge 
in the reservoir below it through the side channel into the upper 

part of the cylinder, before 
"I the exhaust port is covered. 

The incoming charge, al- 
ready slightly compressed, 
helps to drive out the pro- 
ducts of combustion. The 
return stroke compresses 
the mixture, and the cycle 
recommences. 

The simplicity of the 
Day engine makes it easy to reverse its direction of rotation 
As there is only one automatic valve, all that is necessary 
is to change the movement of the flywheel by turning it 




Pig. 62.— Day En^e— 
Sectional Elevation. 




Fig. 63. — Day Engine — Indicator 
Diagram. 



OTHER BRITISH GAS ENGINES. 137 

in the opposite direction. The original type is not suited 
to large powers, even when a twin engine is used, with a 
flywheel between the two cylinders. The speed varies from 
150 to 400 revolutions per minute, according to the size. No 
trials have yet been made on this engine, and, therefore the 
economy claimed for it has still to be verified. Fig. 63 gives an 
indicator diagram of a nominal 1 H.P. engine, indicating 3*3 
H.P. The diameter of the cylinder is 4^ inches, stroke 7^ 
inches, and it runs at 180 revolutions per minute. The Day 
engine is made in sizes from ^ H.P. up to 24 H.P. 

The ** Campbell " engine, manufactured by the Campbell 
Company, at Well Field, Halifax, Yorkshire, is another ex- 
ample of a horizontal engine having two cylinders, motor and 
pump, and obtaining an explosion at every revolution. The 
pump is the smaller, and is worked by a crank on the main 
shaft. The latter also carries an eccentric opening the ad- 
mission valve for gas and air. The vibrating pendulum governor 
acts by partial or total suppression of the gas. The hot tube 
ignition is at the back of the motor cylinder, and below is 
an automatic lift valve for admitting the charge from the 
smaller to the larger cylinder, in which it is compressed. 
The pump piston is at an angle of 90** in advance of the 
motor piston. The charge being first admitted through the 
flat valve, worked by an eccentric from the crank shaft, into 
the smaller cylinder during the out stroke of the pump, it 
is driven by the return stroke to the other cylinder. The 
motor piston being timed to move out later than the other, 
has not yet completed the in stroke, but the exhaust has already 
closed. A vacuum is formed, the automatic valve is lifted, the 
charge, already at a certain pressure, enters the motor cylinder, 
and is compressed during the remainder of the return stroke of 
the motor piston. The pressure drives the gases up the ignition 
tube, where they are fired ; the charge explodes and forces out 
the piston. Thus we have admission in the smaller cylinder, 
and in the motor cylinder, expansion, discharge of the exhaust 
gases, and compression of the fresh charge. No trials appear 
yet to have been published upon this engine. It is made in 
sizes up to 50 I.H.P., and runs at from 150 to 180 revolutions 
per minute. 

Boots. — The special feature of this engine, made by the Roots 
Economic Engine Company, is the compression of tlie gas and 
air. The charge is first admitted into a compression chamber, 
the suction stroke of the piston drawing a portion into the 
cylinder before the admission port closes. This portion is first 
fired, the piston, driven out by the explosion, uncovers the 
admission port, the rich charge in the chamber is compressed, 
ignited, and the pressure raised at once, and well maintained 
throughout the stroke. 



138 GAS ENGINES. 



CHAPTER XL 
FRENCH GAS ENGINES-THE SIMPLEX. 

Contents. — Cycle — Electric Ignition — Slide Valve — Governor — Starting^*' 
Trials— Cheap Gas. 

Among the various gas engines which have appeared during the 
last few years, to compete with the Otto, few have been as ex- 
cellent in design, and as economical in working as the Simplex. 
It was brought out by MM. Delamare-Deboutteville and 
Malandin in 1884, constructed by MM. Matter <fe Cie. at Rouen,' 
and owes the name of •** Simplex" to its simplicity. The 
Otto firm contended that their patent had been infringed in 
France, and brought a law suit against the proprietors of the 
Simplex. In December, 1888, it was decided by the judges in 
favour of the latter. Although the Beau de Rochas cycle is used 
in their engine, and the method of operations resembles that of 
the Otto, several essential differences have been introduced^ 
and the ignition, regulation, and self starter are on a new 
principle. One important modification has been made in the 
cycle, which the inventors claim as an improvement. Ignition 
takes place when the piston has moved a little, and not, as in the 
Otto and most other gas engines, at the dead centre, or before 
the piston has moved. The pngine is horizontal, of the single 
cylinder, single-acting type. 

Simplex Cycle. — In other respects the usual sequence is 
adhered to. There are four operations, each occupying one 
stroke, viz., 1st forward stroke, admission ; Ist return stroke, 
compression ; 2nd forward stroke, explosion and expansion ; 
2nd return stroke, discharge of the gases. Hence there is only 
one explosion for every two strokes forward and two strokes 
return, or every two revolutions, and one motor impulse in four. 
The compression space is more restricted, and the gases are more 
highly compressed previous to explosion, than in the Otto engine. 
Formerly, when ignition was effected by a flame carried in a 
movable slide valve, high initial pressures of the gases were 
diflicult to manage, as the flame was frequently extinguished. 
For this and other reasons the electric spark is preferred to 
ignite the charge in this engine, and renders the pressure 
of the gases, as far as the force and certainty of the explosion are 
concerned, a matter of indifference. Whether they are highly 
compressed, as under ordinary conditions, or slightly compressed, 
as when starting the engine, ignition is equally prompt and 



FRENCH GAS ENGINES— THK SIMPLEX. 139 

effectual. This high initial pressure is a source of economy, 
because a poorer mixture can be used, less gas is required, the 
consumption is smaller, while, with the gases at a higher pressure, 
as much work is done on the piston as if they were ignited at 
the dead point. The piston being allowed to move out a little 
way before the explosion takes place, works more easily and 
quietly. There is less shock to the bearings of the crank shaft, 
and not only the pressure of the gases, but the pureness of the 
mixture is increased, and the products of combustion more 
completely expelled, because of the smaller space into which the 
charge is driven. It is true that the gases do not act upon the 
piston during the same length of time, but the pressure being 
higher, the inventors maintain that more power is exerted, than 
when ignition takes place at the dead point, and that the mechan- 
ical efficiency is higher 

Electiio Ignution. — After careful study of all the different 
methods of firing the charge in gas engines, MM. Delamare- 
Deboutteville and Malandin decided in favour of electricity. 
Their system obviates nearly all the drawbacks attaching to this 
method of ignition, except that a battery and coil are required to 
generate the sparks. The working expense of igniting by elec- 
tricity is said to be about one-fourth less than the hot tube. Of 
all the many devices hitherto resorted to for firing the explosive 
mixture, none of them can be called perfect. The plan originally 
adopted by Otto, but since almost wholly discontinued, of carrying 
a lighted fiame to and fro in the slide valve, was open to many 
objections. The great heat to which the slide valve was subjected, 
due not only to the continual explosions, but also to the perma- 
nent gas flame burning outside, soon deteriorated the quality of 
the iron, made the joints shrink, and coated the ports with 
carbon. Ignition by a hot tube has not these disadvantages, but 
it is deficient in many ways. Unless the gases are at a very 
high pressure and temperature, they will not readily ignite. If 
the tube be made thick, to resist this pressure, it will not become 
red-hot ; if thin, its internal surfaces are continually exposed to 
the flame, while the external surface is at ordinary temperature. 
Hence these tubes require to be frequently replaced. 

In France firing by electricity has been generally adopted. 
As employed by Lenoir and his successors, the system was 
defective, and there were frequent miss fires. The positive 
wire from a Ruhmkorff coil was conducted to the two opposite 
ends of the cylinder, the negative to the engine itself, and 
the circuit closed or interrupted by a contact maker. Pre- 
mature ignition often occurred, and when the electric spark was 
generated inside the cylinder itself, the points of the wires be- 
came coated, and sometimes no sparks were produced. The 
inventors of the Simplex have adopted the ingenious method 
of introducing the two ends of the wires into an isolated chamber 



140 GAS ENGINES. 

in the slide cover, and allowing a continuous stream of sparks 
to play between them. A slide valve moves to and fro between 
the slide cover and the cylinder, at half the speed of the crank 
shaft. At a given moment, a zig-zag passage in the slide valve 
is brought opposite the ignition chamber, and opens communica- 
tion between it and the admission port into the cylinder. Part 
of the charge, already highly compressed by the back stroke of 
the piston, rushes through the passage, is fired by electric 
sparks, and ignites the mixture in the cylinder. The moment of 
ignition, therefore, is regulated, not by the generation of the 
electric sparks, but by the movement of the slide and the 
edges of the port. Premature iguition is prevented by isolating 
the wires in porcelain tubes. 

To work well, this method of ignition requires a pure ex- 
plosive mixture, and that no gases of combustion from the 
previous charge should be left in the firing chamber or the 
slide valve. At the moment when the compressed gases, driving 
before them any residuum of burnt products, pass from the 
cylinder into the oblique passage in the slide valve, and yj^ 
part of a second before the edges of the passage are brought 
opposite the firing chamber, a smull hole opens communication 
with the outer air. This little vent-hole is obliquely in line 
with the firing chamber, to which it is connected by a grooved 
channel in the slide valve and face. So great is the pressure of 
the incoming charge, that all the burnt gases are discharged 
through this opening in even less than the time allotted, and 
the fresh purified charge is ready to be exploded. This system 
of ignition has been found economical and convenient. The 
slide valve and firing chamber are kept comparatively cool, and 
require less attention than with flame or hot tube ignition. The 
regulation of the speed is another special feature of the Simplex 
engine. Two ingenious methods are employed, according to 
the size of the engine ; and the governors are novel in applica- 
tion, if not in principle. 

Fig. G4 gives a side elevation. Fig. 65 a back view, and Fig. 
66 a sectional plan of the Simplex engine. In outward appear^ 
ance it somewhat resembles the Otto, having a single horizontal 
cylinder open at one end, working direct through a connecting- 
rod on to the crank, and a counter shaft to act upon the 
organs of admission, distribution, ignition, and exhaust, driven 
by worm gearing from the crank shaft. A is the motor cylinder, 
P the piston, the connecting-rod, and K the crank shaft. E, 
Fig. 66, is the wheel on the crank shaft, and F another wheel 
gearing into it, of double the diameter, driving the side shaft R, 
which makes one revolution for every two of the crank shaft. B 
is the base plate, M the mixing chamber for the gas and air at 
the back of the cylinder. So far the construction is the same as 
in many other engines ; the horizontal slide valve S, Fig. 66, is 



FRENCH OA8 ENGINES — ^THE SIMPLEX. 



141 




also driven to and fro by the side shaft R in the usual way. In 
Fig. 65, V and Vj are the flywheels, and U and XJi the pulleys. 



U2 



QA8 ENGINES. 



The cylinder is cooled by a water jacket, the water enters at <, 
and is discharged at t^, Fig. 66. e is the exhaust opening at the 
bottom of the cylinder communicating with it through tlie valve 
Sj. The air enters at H, the gas at g, through a pipe at right 
angles to it, seen in Fig. 65. Both pass into the distributing 
chamber M, and from thence through slide valve S into the 
small chamber Bj in the rear of the cylinder, where they are 
compressed by the back stroke of the piston. It is the relatively 
small size of this compression space in proportion to that of the 
cylinder which causes the gas and air to be more highly com- 
pressed than in most gas engines. In an engine of 6*7 B.H.P. 




Fig. 65. — Simplex Engine— End View. 

tested with town gas by Professor Witz, the volume of the 
compression space was 32*4 per cent, of the total cylinder volume. 
With gas of poorer quality, such as Dowson gas, the volume of 
the compression chamber is only 25*6 per cent., in the Otto 
engine it occupies about 36 per cent, of the total cylinder 
volume. 

The side shaft terminates in a small crank, k, working the 
slide valve, and moving it once to and fro for every two revolu- 
tions of the crank shaft. The discharge pipe for the exhaust 
gases is seen at Fig. 64. The exhaust pipe e is closed by the 
valve Sp held upon its seat by the spring y. At a given moment 



FRENCH GAS ENGINES — THK SIMPLEX. 



143 




I 
1 



« cam upon the side shaft R presses down one end of the lever 
L, the other end rises, releases the valve S^ from the springs. 



144 OA8 ENGINES. 

and pushes it up, and the exhaust gases pass out through e. As 
the pressure in the cylinder is 1^ atmosphere when the exhaust 
opens, the valve is lifted a little before the end of the stroke, to 
avoid back pressure on the piston. 

Slide Valve. — Fig. 67 shows a sectional plan of the organs 
of admission, distribution, ignition, and the air governor, all 
of which are at the back of the cylinder. S is the slide valve, 
k the small crank on the counter shaft working it, and M the 
distribution chamber. I'his chamber has three openings, the 
first for the admission of air from below at H ; the second, g^ for 
the entrance of the gas, the valve of which is controlled by the 
air governor G to the right ; the third leads through the slide 
valve into the cylinder, the arrows indicate the direction. At I 
is the ignition chamber, into which the ends of two electric wires 
surrounded by porcelain insulators are introduced, and a con- 
tinuous stream of sparks plays between them, without heating 
the metal. The slide valve has only two openings, a rectangular 
passage, e, shown at Fig. 67, in line with the cylinder port and 
distribution chamber, and an oblique opening, f^ which, as the 
slide moves to the right, brings the lighting chamber I into 
communication with the cylinder through the same port. The 
admission passage is first circular in form, then conical, lastly 
rectangular, and it is thus shaped to ensure the thorough mixing 
of the gas and air as they pass to the cylinder. 

Simplex Governor. — Two simple and ingenious methods of 
regulating the speed have been adopted in this engine. For 
small motors, MM. Delamare and Malandin use an extremely 
sensitive air-barrel governor. If the speed be too great, the 
governor wholly cuts off the supply of gas, and this method 
is not only economical, but by admitting air only for one or 
more revolutions, the cylinder is thoroughly cleansed of the 
burnt products, and the next explosion is stronger, because the 
mixture is undiluted. The governor also regulates the supply 
when the engine is running light. The slide valve S, Fig. 67, 
carries a small horizontal cylinder, c, cast with it in one piece, 
and therefore making one movement forward and back for 
every revolution of the crank A, or every two revolutions of 
the crank shaft. The piston and rod of this cylinder are station- 
ary and fixed to the slide cover, and the cylinder, contrary to 
the usual arrangement, slides to and fro over them with the 
movement of the slide valve. Rubber rings allow the piston-rod 
to move in a slightly oblique direction, as the cover is tightened 
against the slide valve. At the opposite end of the cylinder e 
is a small opening, k\ through which air is admitted and driven 
out by the piston at each forward movement of the slide ; the 
quantity of air is regulated by a micrometer screw, and only so 
much enters at each stroke as will fill the cylinder. At right 
angles to, and cast in one piece with, the upper cylinder c and 



FKENCH 0A8 ENGINES — THE SIMPLEX. 



145 




e 






< 

o 

I 



•I 

a 



6 






the slide valve is a second smaller cylinder, n, the piston of 
-which is free, and usually rests against c. The piston-rod ends 

10 



146 GAS ENGINES. 

in a knife edge, o, fitting into the rod opening the ga£ valve. 
If the speed be normal, a cylinder-full of air is taken into and 
expelled from cylinder c at each to and fro movement of the 
slide valve. The piston of cylinder n does not move, and the 
knife edge o being brought each time by the motion of the 
slide against the gas valve-rod, pushes the valve open, and 
admits a certain quantity of gas. But if the speed be too 
great, the slide valve and, consequently, the cylinder c, make 
more than the given number of movements. More air is 
admitted into cylinder c than can be driven out during one 
revolution. It is compressed, the pressure acting upon the 
piston in n drives it down, and the knife o misses the edge 
of the gas valve-rod, as seen in the dotted line. Fig. 67. No 
gas can thus enter until the speed of the engine and, con- 
sequently, the pressure in tlie upper cylinder are reduced. 

MM. Delamare and Malandin have lately introduced a modi- 
fication of this method of governing, by which the speed of the 
engine can be still more delicately adjusted. With their air 
governor, as with most others, there is no alternative between 
admitting the full quantity of gas, and wholly suppressing it. 
Sometimes, however, the speed varies within such small limits 
that it is unnecessary to cut off the gas supply entirely. In 
such cases the speed is regulated by altering, not the amount of 
gas, but the quantity of total mixture admitted, the proportion 
of gas and air remaining the same. Thus the charge will always 
ij^nite, but, with the slightest increase beyond the normal speed, 
a weaker explosion is produced. 

This effect is obtained by means of a rod through the centre 
of the mixing chamber M, Fig. 67, pierced with a hole to allow 
the spring of the gas valve 8 to pass across it, and terminating 
in two discs, one behind the other (not shown in the drawing), 
cut with alternate open and closed sections. The direction of the 
rod is the same as that of the arrows, and it carries a projection. 
The discs are placed across the chamber M, just before it narrows 
to the slide-valve port e. The inner disc is stationary, and fixed 
to the valve cover ; the outer disc moves with the rod. Close to 
the projection, and held against it by a spring, is a small cylinder 
and piston communicating with the air-barrel cylinder c. When 
the engine is running at its normal - speed, the openings in the 
discs correspond, and the mixture freely enters the cylinder from 
the chamber M, the small cylinder and piston remaining at rest. 
If the speed be slightly increased, more than the right amount of 
air enters the cylinder c, but not enough to drive down the piston 
in w, and wholly cut off the gas supply. This surplus air passes 
into the small cylinder against the rod, drives up its piston and 
the projection, and the rod and disc attached to it move round. 
The openings of the two discs no longer correspond exactly, a 
smaller portion of the charge is admitted through them, and the 



FRENCH GAS ENGINES — THE SIMPLEX. 



U7 



strength of the explosion is proportionally reduced. This method 
of varying the power of the engine within very small limits is 
applicable to any gas motor. 

For larger engines a simpler and cheaper governor has been 
introduced. It is constructed on the principle of two pendulum 
weights, a lighter and a heavier, swinging on a fixed pivot at 
either end of a rods The time occupied by the fall of the pen- 
dulum is always the same ; the variation in the speed is obtained 
by a weighted knife blade acting upon the gas valve. Figs. 68 
and 69 show the arrangement of the pendulum governor, also 
Been in Fig. 65. The two weights of the pendulum, Q and O, 
are mounted on a rod ending in a notch, N, and held in position 




Fig. 69. — Simplex Engine — Pendulum 
Governor. 

by the pivot r in the centre. The 
heavier weight O is fixed to the lower 

Fig. eS.— Simplex Engine— ®^4 ^^ *^® ^^^ ' ^^^ "PP®^ *^^ lighter 
Pendulum Governor. weight can be adjusted by a screw to 
any distance from the middle of the rod, 
to give the required length of swing for any speed. The heavier 
weight being below, the tendency of the pendulum is always 
towards an upright position. Bolted to the slide valve of the 
engine, and therefore moving to and fro with it, is a frame 
carrying a knife blade, ft, square and weighted at one end, and 
pointed at the other. The pendulum and the notched opening 
of the gas valve ^, shown to the left, are both in the stationary 
valve cover, the weighted blade on the frame moves with the 
slide valve. As the square part of the blade is the heavier, the 
piece of iron, unless prevented, always remains vertical ; but 
each time the knife blade in its motion encounters the pendulum 
as it swings, the point of the blade is caught by the notch and 



148 



OA8 ENGINES. 



held in position, and the square end of the knife pushes open 
the gas valve. If, however, the speed of the engine be too great^ 
the slide valve carries the knife blade forward too soon, as seen 
in Fig. 68. The blade misses the notch, the weighted end drops 
below the gas valve, and no gas is admitted. This governor is 
almost as. sensitive as the other, because, the fall of the pendulum 
being always the same, the regulation of the speed depends on 
the hit or miss of the notch. 

From this description it will be seen that the Simplex engine 
differs in many important respects from the Otto, especially in 
the ignition, which, M. Delamare asserts, is simpler, cleaner, 
and more certain than the usual firing. The higher pressure 
obtained by reducing the compression space, the greater heat of 
the electric spark, and the more complete discharge of the 
exhaust gases, increase the economy and efficiency of the engine, 
and make it especially fitted for driving with Dowson or 
other poor gas. To set up a complete gas-generating plant, 
however, is only remunerative for large power engines, and 
it is under these circiimstances that the Simplex reaches its 
maximum of economical working. 

Starting. — The construction of the engine renders it easier to 
start than most other gas motors. As the electric spark is 





Fig. 70.— Simplex Engine 
StartiDg Gear. 



Fig. 71. — SimjJex Engine— 
PositioDs at Starting. 



sufficiently powerful to ignite gases at any pressure^ preliminary 
compression, always a difficult matter, is not necessary to any 
large extent. A simple method of starting was introduced and 
patented by MM. Delamare and Malandin in 1888. A three- 
way cock, shown in plan, section, and elevation at Fig. 70, is 
connected to the ignition and main gas supply. The gas is 
admitted from below, and the air at the side into the ignition 
chamber, and pass through the oblique slide valve opening into 
the cylinder in the direction of the arrows. Fig. 71 shows a 
diagram of the movements of the piston. 

The special and original feature of the Simplex self-starter is 
that the explosive mixture, instead of being introduced during 



FRENCH GAS ENGINES — ^THE SIMPLEX. 149 

the admission stroke, enters the cylinder during the third or 
expansion stroke. All attempts to start the engine when 
admitting the charge as usual during the first forward stroke 
failed, because so long a time elapsed, viz., a forward (admission) 
and back (compression) stroke, before it was fired. But as soon 
as the " lucky idea," as the inventor calls it, was hit upon, of 
admitting the charge at the beginning of expansion, the engine 
was easily started, because the gases were immediately tired, and 
driven out during the course of the next exhaust stroke. 

To set the engine in motion, therefore, the piston must be 
stopped at c, Fig. 71, at the end of compression, and the com- 
pressed gases allowed to escape. The gas cock and the three-way 
<x>ck are then opened, and the flywheel turned by hand, until the 
piston has moved to e through three-quarters of its next forward 
stroke. Gas and air, mixed in the proportions allowed by the 
openings of the three-way cock, enter the cylinder to fill the 
vacuum caused by the forward motion of the piston. The cocks 
of both pipes are then turned off, the movement of the flywheel 
reversed, and the piston returning to gj, slightly compresses the 
'charge of gas and air behind it. The electric current is then 
switched on, and although the gases are at a low pressure, the 
spark is sufficiently powerful to ignite them, an explosion follows, 
and the engine is fairly started. For larger engines, where it is 
difficult to turn the flywheel by hand, the engine is started still 
more easily and simply. It must be stopped at/, Fig. 71, in the 
middle of the ignition stroke, and the gas and air allowed to 
enter through the three-way cock. At the top of the cylinder, 
above the compression chamber, there is a small hole closed by 
a pet-cock. This is opened, and the mixture of gas and air 
entering the cylinder at a slight pressure drive out, through it, 
the burnt products remaining from the previous charge. As 
soon as the hole is closed, the three-way cock being still open, 
the gas and air accumulate behind the piston and in the ignition 
•chamber. The ordinary gas cock is then opened, a fresh charge 
enters, the current is switched on, an explosion follows, and the 
engine begins to move. In the later engines the pet-cock is 
replaced by an auxiliary cam on the counter shaft, which keeps 
the exhaust open and diminishes the pressure, until the engine 
is at work. In both these methods of starting the principle is 
the same, namely, to introduce gas into the cylinder by other 
than the regular means, and at an unusual period in the cycle. 

The single cylinder 100 H.P. nominal Simplex engine at- 
tracted much attention at the Paris Exhibition of 1889, and 
was highly commended for economy and efficiency. Worked 
with Dowson gas made in a special generator, the consumption 
•of coal per I. H.P. per hour was about half that in a steam 
engine of the same power. This engine was one of the best 
representative types then made of an economical gas motor. It 



150 



GAS ENGINES. 



had two flywheels, each 51 feet in diameter, the diameter of the 
cylinder was 23 inches, length of stroke 3 feet 2 inches. The 
mean speed was rather less than the avei-age, the engine running 
at 100 revolutions per minute, and the initial pressure of the 
gases 6 atmospheres. The mechanical efficiency was only 69 per 
cent. Few gas engines of the same H.P. are able to dispense 
with a second cylinder. In the opinion of Professor Witz, the 
success of this Simplex engine has established beyond a doubt 
that large power gas engines, when using cheap or Dowson gas^ 
are able not only to compete with steam engines, but to surpass 
them considerably in economy. The saving effected by the use 
of Dowson gas, manufactured on the spot, instead of the 
expensive Paris gas, was very marked. MM. Delamare- 
Deboutteville and Malandin are now making engines, all single 
cylinder, to be. worked with town gas, of the following sizes: — 
From 1 H.P. to about 150 H.P.; for Dowson or other poor gas 
from 30 H.P. to 150 H.P. 

Trials. — Different sizes of the Simplex engine have been 
tested by Professor Witz. Trials of the 100 H.P. engine will be 
found in the table at p. 404. 

These experiments were continued for four successive days, 
and the calorific value of the Dowson gas used was 1487 calories- 




Fig. 72. — Simplex Engine — Indicator Diagram. 

per cubic metre, at ordinary temperature and atmospheric 
pressure. The brake H.P. of the engine was 75-86, and the 
consumption 83*7 cubic feet of Dowson gas per B.H.P. per hour,. 



Lbt. 

no 

100 


i 


\ 


K 




IH 


/ 




\ 


n*^ 




I 






'^"T^^^^^,,,^,,^^^^ 








-— 


--i-j^. 1' {^ 



P«r«*itt«ft •t Strok*. 

Fig. 73. — Simplex Engine — Indicator Diagram of 8 H.P. Engine. 

or 1*3 lbs. of coal per B.H.P per hour. Fig. 72 shows a diagram 
taken during the trial. In a smaller engine tested by Professor 
Witz in 1885, the B.H.P. was 6*8, and the consumption of 
ordinary lighting gas 21 '8 cubic feet per B.H.P. per hour. An 



THE MODERN LENOIR AND OTHER FRENCH ENGINES. 151 

engine of nearly twice the size showed a brake consumption of 
19-4 cubic feet per hour. Fig. 73 is a diagram from an 8 H.P. 
Simplex engine. 

Engines for Poor Ghts. — MM. Delamare and Malandin are still 
studying to perfect their engine, and have taken out 60 patents 
in France, and 10 in England. A list of the latter will be found 
in the Appendix. They have lately designed a new type with 
many modifications in detail, in which the calorific value of the 
gas is said to be much better utilised. The author regrets that 
the plans of this new engine are not yet sufficiently advanced for 
publication. Recently they have adopted the Lencauchez system 
of poor gas for driving their engines, and have erected several 
important installations in France, combining the Lencauchez 
generator and the Simplex engine. All of them are intended 
specially for burning poor and cheap coal. The system is 
described at p. 197. 



CHAPTER XII. 

THE MODERN LENOIR AND OTHER FRENCH 
ENGINES. 

Contents. — Modem Lenoir — Charon — Tenting — Ravel — Forest — Niel — 
Lalbin — Varioua. 

Singe the introduction of his first motor in 1860, Lenoir, the 
pioneer of gas engines, had been incessantly working to perfect 
his invention and to remedy its defects, especially the large con* 
sumption of gas. Sixteen years later, in 1876, a new direction 
was given to the efforts of mechanical engineers by the appear* 
ance of the Otto. The success of this motor conclusively proved 
the truth of Beau de Bochas' theory, that, without compression 
of the gases before ignition, it is impossible to make an engine 
work economically. Abandoning, therefore, the lines on which 
he had formerly worked, Lenoir announced his adherence to the 
principle of compression by introducing, in 1883, an engine in 
which the Beau de Rochas cycle was closely followed. 

Modem Lenoir. — Like the Otto, the modern Lenoir engine 
has one motor impulse in four. The first stroke (forward) draws 
in the mixture of gaa and air, the second stroke (return) com- 
presses the charge ; during the third stroke (forward) it is 
exploded and expanded, doing positive work ; and in the fourth, 
stroke (return) the products of combustion are discharged. The 
cycle of this new engine is generally similar to that of the 
Otto, and like the inventors of the Simplex, Lenoir had to 



152 OAB ENGINES. 

encounter a lawsuit in France, which was decided in his favour 
in August, 1885. There are, however, essential points of differ- 
ence, as well as of resemhlance, in the two motors. Lenoir aims 
at obtaining higher compression of the gases. By separating the 
chamber in which they are compressed from the working cylinder, 
and keeping it hot, while the cylinder is cooled by a water jacket, 
he contrives to heat the gases before ignition, without unduly 
raising the temperature of the piston. As in the former engine, 
the electric spark produced for each explosion is employed to 
ignite the gases, but his particular method of ignition does not 
seem to give a perfectly regular speed. Whatever its merits when 
skilfully handled, it is, in the opinion of Professor Schottler, a 
step in the wrong direction to fire the gases electrically. In 
other respects the mechanical details of this Lenoir engine are 
good, and carefully stiidied. The high pressure at which the 
gases are ignited gives greater expansion after explosion, the 
mixture can be much diluted or a poorer gas used, and greater 
economy is thus obtained. The piston moves out so little dur- 
ing explosion, that ignition practically takes place at constant 
volume. 

The cylinder is in reality divided into two distinct parts, the 
motor cylinder, in which the piston works, and the compression 
chamber at the back, separated from it by an asbestos joint. 
This chamber, called by the inventor a " rebeater,'' is a distin- 
guishing feature of the engine. The cylinder is surrounded by 
a water jacket, but radiating cast-iron ribs, offering a consider- 
able surface to the air, are sufficient to cool the compression 
chamber, because the piston does not enter it. Thus the incom- 
ing gases, as they pass through this chamber, which is much 
hotter than the cylinder, are heated prior to ignition, and the 
heat imparted to them increases their pressure. Before explo- 
sion it rises to 4 atmospheres (about 60 lbs.), and after explo- 
sion to 13 atmospheres, and to 16 atmospheres in engines 
using carburetted air. This high pressure and temperature make 
the gases ignite easily, although a poor and greatly diluted 
mixture is used. Another novelty in this engine is that the 
admission and ignition valves are at the side of the cylinder, in 
a relatively cool position, and therefore need little oiling. The 
electric wires never come in contact with the lubricant, and 
there is no danger of the ends beconnng greasy. Air and gas 
are admitted and mixed in a distributing chamber, as seen in 
the drawing. 

Fig. 74 gives a sectional plan of the modem Lenoir engine, 
showing the different parts. A is the motor cylinder, with 
piston P, B the compression chamber suiTounded by the ex- 
ternal ribs, E is the opening for the exhaust at the further end 
of the compression chamber, D the valve ohest at the side of 
the cylinder, containing chambers for the admission, mixing, and 



THB llODBBN LENOIR AND OTHEB FRENCH ENGINES. 



153 




-3 
§ 

J 
OC 

a 
!^ 

.a 

S 

e 



&4 



ignition of the charge. At a is the asbestos joint separating the 
•cylinder casting from that of the compression chamber, to pre- 



154 OAS ENGINES. 

vent the conduction of heat. A portion of the piston-rod is 
seen at p^ working through the connectincr-rod and a strong 
cylindrical guide g on to the crank shaft K. All the organs 
of admission, distribution, ignition, and exhaust are worked by 
a counter shaft, E., driven from the main shaft by two spur 
wheels, e and /, in the proportion of 2 to 1. The shaft B, 
therefore, revolves at half the speed of the crank shaft. Upon 
it are two cams, t' and f, and a projection, v ; these work the 
exhaust and admission valves, and the ignition. The exhaust 
E is opened by the lever N and the rod O. At a given 
moment the cam T.on the counter shaft pushes out the valve- 
rod O, the lever N is displaced, and the exhaust port un- 
covered. 

The valve chest D is divided into two parts, J the admission, 
and I the mixing and ignition chambers, and communication 
between them is made through a horizontal valve, H. The air 
enters from below at tw, and the gas from above ; the governor 
acts upon the gas admission pipe. To admit the gas into 
chamber J, the second cam t' on the counter shaft R pushes out 
the rod t and lifts a valve placed on the gas supply pipe. Unless 
checked by the governor, the gas enters through several holes, 
and becomes thoroughly mixed with the air, before the valve H 
opens to admit the charge into the inner chamber I. From 
thence it passes through the channel g into the cylinder, and 
is compressed into B. The charge is fired at h on the same 
principle as in the earlier Lenoir motors. Two wires, positive 
and negative, pass from a BuhmkorfT induction coil, the one 
into the engine, the whole of which becomes negative, the other 
from u to h a.t the side of the admission chamber. Contact is 
interrupted or established by the projection v on the counter 
shaft R, which at a given moment in the cycle of the engine 
closes the circuit. The spark is produced, and part of the 
highly compressed charge in B, driven up the narrow passage 
g by the return compressing stroke, is ignited, and spreading 
back into the cylinder fires the remainder. The passage is 
always open to the cylinder, but the charge cannot ignite until 
the maximum pressure is reached, and the spark produced. An 
india-rubber bag is used to regulate the pressure of the gas. 
Little difficulty is apparently found in starting this engine, the 
process being always easier in engines firing electrically than 
in those which use fiame ignition. The counter shaft R carries 
a second smaller cam, as well as the cam opening the exhaust, 
and both can be brought into play when starting the engine. By 
means of the second cam, the exhaust valve is opened twice during 
one revolution of the crank, to diminish the pressure of the gases 
in the cylinder. As soon as the engine is at work, the handle 
moving this cam falls back automatically. The gas valve can 
also be opened independently of the governor. 




THE MODERN LENOIR AND OTHKR FRENCH ENGINES. 155 

M. Tresca, who had been the first to experiment upon the 
original Lenoir motor, undertook two series of trials upon the 
modern engine, driven alternately with gas and with carburetted 
air. Tests were made on a 2 H.P. nominal engine with Paris 
gas in 1885, and the mean of three experiments gave a con- 
sumption of 24 cubic feet of gas per B.H.P. per hour. The 
indicator diagram is shown at Fig. 75. The engine ran at 176 
revolutions per minute, and the mechanical efficiency was 74 
per cent. The dimensions of the 
cylinder are given in the table, 
p. 402. Another experiment was 
made in 1890 by M. Hirsch on a 
16 nominal H.P. Lenoir engine, in 
which the consumption of Paris 
gas per B.H.P per hour waa a 
little over 21 cubic feet. It must pjg 75. -Modern Lenoir Engine 
not be forgotten tliat in all en- —Indicator Diagram, 

gines firing the charge electri- 
cally, the consumption of gas is slightly less than where flame 
ignition is used, because in the latter case a small quantity of gas 
is required to feed the light. M. Tresca died before the results 
of his experiments were published. The constructors of the 
Lenoir engine claim for it an average consumption of 23 cubic 
feet of gas per I. H.P. per hour. 

For sizes above 8 H.P., the Lenoir motor is usually made 
with two cylinders and pistons, working upon the same crank 
shaft. A single counter shaft between them drives the admission 
and ignition valves and the governor. There is only one mixing 
chamber, communicating alternately with each cylinder, and one 
commutator, to pass the spark to either cylinder as required. 
One explosion per revolution of the motor crank is thus obtained. 
Sometimes all the parts are made in duplicate, and the engine 
virtually consists of two single cylinder motors. The Lenoir 
engines are made at Paris by MM. Bouart Frer^s, and by the 
Compagnie Parisienne d*£clairage au Gaz. 

Charon. — The Charon engine, sumamed the " Incomparable,'^ 
was patented in 1888, and shown in the French Section of the 
Paris Exhibition of 1889. It is a horizontal four-cycle single 
cylinder engine, resembling the Otto in outward appearance 
and mechanical details, with lift valves and electric ignition. 
To obtain greater expansion in proportion to admission and 
compression of the charge, a novel feature is introduced in the 
construction of the engine. The student will already be familiar 
with various devices of this kind, but the method employed by 
M. Charon, although original, is complicated, and cannot be con- 
sidered as ofiering a successful solution of the difficulty. 

As in most types of engine using the Beau de Kochas cycle, 
the piston makes two forward and two return strokes for two 



156 GAS ENGINES. 

revolutions of the crank. The first out stroke of the piston 
draws in the charge, the second return stroke compresses it. 
The gas and air are then fired by the electric spark a little 
before the end of this stroke, and the charge is exploded before 
the piston begins its third stroke (out). The whole of this stroke 
is utilised in expansion, and during the fourth stroke (return) 
the products of combustion are discharged. The novelty of the 
engine is that, when the piston has reached the end of the first 
out stroke, the cylinder behind it being full of gas and air, the 
gas valve closes, but the air admission valve remains open during 
tlie first part of the return compression stroke. This valve 
communicates, through a pipe, with a circular spiral passage or 
coil in a chamber below. The other extremity of this coil is 
open to the atmosphere, and the air is drawn in through it. A 
portion of the gases, instead of being compressed in the cylinder, 
pass through the valve, and are stored up in the spiral passage. 
The valve then closes, and during the remainder of the second 
stroke (return), the charge is compressed by the piston in the 
usual manner. At the next admission stroke the air valve again 
opens, as well as the gas valve, to admit a fresh charge. Air is 
drawn in from the coil by the suction of the piston, carrying 
along with it to the cylinder the gases stored from the previous 
charge. The next compression stroke refills the spiral coil, the 
diameter and length of which are so proportioned that the com- 
pressed gases are prevented from reaching the opening, and 
escaping into the atmosphere. 

The operations of admission, ignition, and exhaust are effected 
by lift valves, worked by cams on a side shaft. The cam open- 
ing the gas valve is controlled by the governor. The electric 
wires are carried into a small chamber at the back of the 
cylinder, immediately above the admission valve. Contact is 
interrupted by a lever moved by a cam on the side shaft, and 
the spark is produced just before the crank reaches the inner 
dead point. Extreme care is taken in this engine to determine 
the precise moment of ignition. The exhaust and air admission 
valves are driven from a small shaft at the back of the cylinder. 
At right angles to the side shaft, to which, at each revolution of 
the latter, an oscillating movement is communicated by two 
cams. The speed of the engine is ingeniously regulated on the 
following principle : — The governor acts, not only on the gas 
Admission cam, but upon the cam opening the air valve. The 
greater the speed, the longer this valve is kept open. More of 
the gas and air pass into the spiral coil, less are retained to be 
compressed in the cylinder. Thus the charge will be poorer in 
quality and less in quantity, until the speed is reduced within 
normal limits. The exhaust valve is the same in principle as in 
the Otto engine. 

A 4 H.P. Charon engine was tested in 1889 at Solre-le- 



OTHER FRENCH ENGINES. 157 

Chateau, France, by Professor Witz, and the consumption was 
found to be 19 cubic feet of gas per hour per H.P. Details of 
the experiment are not given, because the results were not 
considered satisfactory. Full drawings of the engine will be 
found in Witz and Chauveau.* 

Tenting. — The Tenting, made by MM. Salomon and Tenting, 
at Paris, is a horizontal single-cylinder engine, simple in con- 
struction, and using the Beau de Rochas cycle. There is no 
slide valve. Admission of the charge is effected from a central 
opening below the cylinder, through which passes the rod of an 
automatic valve, held back by a spring. Gas and air, in proper 
proportions, enter the cylinder through a series of concentric 
holes below this valve. It is lifted by the suction of the motor 
piston during the admission stroke, and closes when the pressure 
in the cylinder, during compression and exhaust, is greater than 
that of the atmosphere. A valve-rod at the side of the cylinder, 
driven by wheels from the main shaft in the proportion of two to 
one, opens the exhaust valve. The centrifugal ball governor acts 
upon this rod through a lever. As long as the speed is normal, 
the lever rests against the cylinder ; but if it be increased, the 
lever is drawn forward, and a projection upon it is interposed 
between the spring closing the exhaust and the valve-rod. As 
the exhaust valve cannot close, the pressure in the cylinder does 
not fall below that of the atmosphere, and the automatic admis- 
sion valve is thus prevented from rising. No fresh explosive 
mixture enters until the speed is reduced, and the lever allowed 
by the governor to right itself. 

This engine has no water jacket for powers below 4 H.P. The 
cylinder is surrounded by a hollow casing divided into compart- 
ments, through which air circulates, entering at the bottom, and 
passing out at the top. The air can be replaced by water if 
desired. Electric ignition was used at first in the Tenting engine. 
The negative wire was joined to any part of the engine, and 
contact was established between it and the positive wire by an 
isolated metallic column and a disc attached to the auxiliary 
shaft. At the moment of ignition, a small porcelain pin or in- 
sulator, carried round on the disc, interrupted the current, which 
passed to a point above the compression chamber of the cylinder ; 
the electric spark was produced, and the mixture fired. Firing 
by electricity has now been abandoned in favour of hot tube 
ignition. 

Bavel. — Two varieties of the Ravel engine have already been 
described, but the inventor has lately re-modelled the design. 
In 1888 M. Ravel introduced a horizontal engine of the Clerk 
type, giving an explosion every revolution. There is one motor 
cylinder and i>iston. The cylinder is closed at both ends, and 

* Gustave Chauveau, ** Traitt tlUorique e( pratique des Moteurs d Oaz,'' 



158 OAS ENGINES. 

air is drawn in at the crank shaft end, and compressed into a 
reservoir in the base of the engine, while expansion is taking place 
on the other side of the piston. The gas is admitted into a 
separate pump, and compressed into a second reservoir before 
entering the cylinder. Each forward stroke is a motor stroke, and 
corresponds to one revolution of the crank. Although both gas 
and air are thus previously compressed, the pressure of the ignited 
gases and their consequent expansion is not so great as might 
have been expected, and is, to a certain extent, sacrificed to 
regularity of working. The exhaust openiligs are placed near the 
crank shaft end of the cylinder, and are uncovered by the piston, 
when it has passed through about two-thirds of the expansion 
stroke. The additional complication of the pump and reservoirs 
for the gas and air, and the deficient expansion, due to the early 
opening of the exhaust, are undoubtedly defects in this engine. 

The construction is rather complicated. The air, after being 
drawn into the front part of the cylinder, and compressed through 
an automatic lift valve into the reservoir formed in the base 
plate, passes into the mixing chamber. The gas is first com- 
pressed in the pump, the piston of which is worked from the 
crosshead of the motor ))iston, then delivered into the small 
reservoir above the air reservoir, the pressure in both being the 
same. It then enters the mixing chamber, and two valves 
worked by a single rod, and opened by a cam on the crank shaft, 
admit the gas and air to the cylinder. Meanwhile the exhaust 
valve and lever, acted on by another cam on the crank shaft, are 
lifted. The immediate lowering of pressure, caused by the 
opening of the exhaust ports, draws in the mixture through an 
oblique passage, which gives it a spiral motion, helping to drive 
out the products of combustion. It is necessary to prevent part 
of the fresh charge from escaping with the exhaust gases, and 
this, according to the inventor, is effected by the circular motion 
imparted to the charge by the shape of the admission passage. 
The return stroke of the piston covers the exhaust ports, and 
the fresh charge is then further compressed. Just before the end 
of the stroke it is driven into a chamber at the back of the 
cylinder, the electric spark is produced, and the charge fired. 
Thus by the time the piston has reached the inner dead point, 
explosion has already taken place, and expansion follows. In 
this way the charge is twice compressed, and the pressure twice 
utilised. After being compressed separately by the auxiliary 
gas pump and the outer face of the motor piston, the gas and 
air enter the cylinder under their reservoir pressure, and clear 
it of the products of the former charge. The mixture is then 
compressed afresh by the motor piston, the charge is exploded, 
and drives the piston forward, doing work. 

Notwithstanding these high pressures M. Ravel has preferred 
not to utilise fully the power generated for the expansion stroke, 



OTHER FRENCH ENGINES. 159 

but to employ moderate pressures, and to obtain a steady rate 
of workiDg. He has also sacrificed economy to regularity in the 
action of the governor. A centrifugal governor is used, placed 
above the pipe admitting the gas to the pump, and the supply 
of gas is regulated according to the speed. A certain quantity 
is always allowed to pass through the cylinder, but if that 
quantity be too small to ignite, it escapes unbumt. The varia- 
tion is in the quality of the charge, and the engine is said to 
work with great regularity, but somewhat extravagantly. In 
economy it is easily su]^)assed. The main objects aimed at by the 
inventor have been to produce an engine running so regularly that 
it can be utilised for electric lighting, and to obtain a .working 
impulse every revolution, instead of every two revolutions, of 
the crank. In a trial made on an 8 H.P. engine, the highest ex- 
plosive pressure was 8*6 atmospheres, and the consumption of 
gas (French) 33 cubic feet per I.H.P. per hour. The indicator 
diagrams show a low explosive pressure, but comparatively great 
expansion. By adjusting a screw on the governor, the balls can 
be raised or lowered, and the speed varied from 40 to 160 
revolutions per minute. Drawings of this engine will be found 
in Witz and Chauveau. 

Forest. — A new variety of the Forest engine, described at 
p. 71, was brought out at the Paris Exhibition of 1889. In 
this motor M. Forest has adopted the usual method of com- 
pression of the charge before ignition, the Beau de Hochas cycle 
is used, and an explosion obtained every other revolution. 
There is a single horizontal cylinder, having two motor pistons 
each attached to a lever, and moving in opposite directions. 
The crank shaft is above, and is driven by two connecting-rods, 
and two cranks 180" apart. The charge is admitted in the 
space between the pistons as they move out, compressed to 
5 atmospheres, and ignited electrically. The explosion takes 
place between the two pistons, forcing them apart, and acts 
through the levers upon the two cranks. Greater compression 
is thus obtained, but otherwise the engine does not seem to have 
much to recommend it It is a compact little motor, but there 
are a good many moving parts. A drawing will be found in 
Witz. M. Forest has devoted his attention more particularly to 
marine and petroleum engines, with reversible motion and 
automatic starting gear. These will be described in the Oil 
engine section. 

Kiel. — The Niel, which first appeared at the Paris Exhibition 
of 1889, is a well-designed horizontal single-cylinder compres- 
sion engine of the Otto type, but with several ingenious modi- 
fications. The admission, distribution, and exhaust valves are 
worked from a side shaft, geared from the main shaft by worm 
wheels as usual. The exhaust only is a vertical lift valve ; the 
admission gear is novel in principle and arrangement. It 



160 



GAS ENGINES. 



consists of a conical revolving valve which, when brought to 
face the cylinder ports, governs the admission and compression 
of the charge. The gas and air enter the cylinder through 
openings in the valve. By this rotatory movement the charge 
is drawn in, usually in the proportion of 1 of gas to 8 of air, 
by the forward stroke of the piston. To reduce the shock, 
and make the engine work more smoothly, admission lasts 
only during two-thirds of the first forward stroke and the 
charge expands slightly during the last third. Thus admis- 
sion is less in proportion to expansion, but this advantage is 
counter-balanced by the correspondingly smaller compression. 
The eifect of this variation from the usual cycle is seen in the 
diagram, where the admission line falls at the end slightly below 
atmospheric pressure. In the return stroke the conical valve 
opens communication between the contents of the cylinder and 
the hot ignition tube. It is during this period of compression 
and explosion, that the difficulty of preventing leakage is ex- 
perienced with all slide and rotating valves. M. Niel obviates 
it in an ingenious way, and even turns it to account. A thin 




Fig. 76.— Niel Engine— Sectional Plan. 

metallic diaphragm in the conical valve is so arranged, that 
it is acted upon by the pressure of the gas in the cylinder. 
Thus the valve is made to fit more closely in its socket when the 
pressure in the cylinder is at its maximum, the pressure on the 
conical part is then greatest, and leakage is minimised. The 
discharge of the gases does not take place through this valve, but 
through an ordinary vertical lift valve, opened by a lever below 
the cylinder, and a cam on the side shaft. Fig. 76 gives an 



AAtmo»j)h 



OTHER FRENCH ENGINES. 161 

elevation of the Niel engine, showing the side shaft and method 
of driving it, tlie conical distributor, ignition, and oiling ap- 
paratus; the exhaust is on the opposite side of the cylinder. 

The oscillating governor consists of three arms, one of them 
weighted, moving round a fixed point. Under normal working 
conditions, one of the arms at each revolution reaches and opens 
the gas admission valve ; but if the speed be too great the arms 
are thrown out of position, the valve is missed, aud no gas 
admitted. The speed is regulated in somewhat the same way as 
in the Simplex pendulum governor. Drawings of all the 
different parts of this engine, and a complete description by 
M. Auguste Moreau, will be found in Comptea Rendus de la 
SocieiS des Ingenieurs CiviUy October, 1891. 

Trials. — A series of careful experiments upon a 4 K.P. nominal 
Niel engine were made by M. Moreau. An indicator diagram taken 
during the trial is given 
at Fig. 77. The temper- 
atures of the gases and 
of the water in the jacket 
were determined, and 
nothing was omitted to 
make the experiment as 
complete as possible. M. 
Moreau found that, when 
running at 160 revolu- 
tions per minute, with ^^K- 77.— Niel Engine— Indicator Diagram. 
a maximum pressure of 

12 to 14 atmospheres, the mean consumption of Paris gas was 
27*2 cubic feet per hour per B.K.P., but the engine was of an 
early type, and the construction has since been improved. The 
mechanical efficiency was 75 to 80 per cent. The Niel engine 
is compact, and works regularly and quietly. More than one 
hundred of these motors, a large number for France, are said to 
be now made in the course of the year, but mostly for small 
powers. 

Lalbin. — The Lalbin exhibits a new and ingenious type 
of gas motor, with three cylinders. M. Lalbin*s object has 
been to construct an engine small in size, combining the maxi- 
mum power with lightness, and his 8 H.P. motor weighs only 
770 lbs.; he has also succeeded in making it reversible, and 
applicable to gas, oil, or carburetted air. It is a four-cycle 
engine with three motor pistons, all working upon the same 
motor crank through connecting-rods, with their three cylinders 
arranged equidistant round a circle. The complete cycle is 
carried out in each cylinder in two forward and two return 
strokes, and is so arranged that three motor impulses are im- 
parted to the crank during two revolutions, and therefore a 
small flywheel is sufficient. The motive power is more uniform 




162 



OAS BirOIKBS. 



than 18 itsiial in gas motors, and only one-sixth of a revolution' 
intervenes between each stroke. Fig. 78 gives a sectional 
elevation of the Lalbin engine, showing the three cylinders and 
pistons, with the crank in the centre. Each cylinder is com- 
plete in itself, and has its separate valves for admission, 
ignition, and exhaust. The admission valves are automatic; 
tube ignition is used when the engine is worked with gas, and 
electricity when driven with carburetted air. These features 
are to be found in other engines, but the exhaust valves are 
original in design. They are opened by a cam on a disc revolv- 
ing with the crank shaft, but as they require to be lifted only once 
every other revolution, an ingenious hit-and-miss contrivance 
has been adopted. During one revolution the valve-rod misses 
the disc, the next time it fits into it, and the exhaust is opened. 
The engine is easily reversed by turning the disc in the opposite 
direction, and making the ignition of the charge take place a 




Fig. 78. — Lalbin Engine — Sectional Elevation. 

little soonei*. The Lalbin is a new engine, and still on its trial. 
Time alone can show whether this three-cylinder arrangement 
has any practical advantage over the single-cylinder type, and 
whether, as M. Witz thinks, the engine has a great future before 
it. Probably the mechanical eflSciency will be low. Full details 
and drawings are given in Witz, p. 311. 

The Diederichs engine, manufactured by the firm of Belmont, 
Chabond & Diederichs, at Bourgoin, Is^re, France, will be 
described among the petroleum motors. It is seldom worked 
with gas. 

Various. — A few of the engines already mentioned in the 
historical chapters are still occasionally made in France. These 
are the Bonier, Etincelle, the Noel, and the Francois. Others 
have only a local reputation, as the Cazal, Delahayes, Poussant> 



GEBMAH GAS ENOINES. 163' 

Boger, Letombe ; le Robuste, made at Evreux, and the Mille at 
Lyons. The relatively small number of gas engines constructed 
in France, with the exception of the Simplex and the Niel, is in 
striking contrast to the much greater number and variety made 
in England, and is probably due to the higher price of fuel and 
gas in France. This accounts for the popularity of the Simplex 
engine, which is especially adapted for working with cheap gas. 
MM. Delamaro and Malandin are said to supply from one-third 
to one-half the gas motors produced yearly in France. English 
and German engines are also imported. 



CHAPTER XIII. 

GERMAN GAS ENGINES-THE KOERTING-LIECKFELDT, 
ADAH, AND BENZ. 

CoNTKNTS.— Koerting-Lieckfeldt Original TVpe— Type of 1888— Ignition- 
Governor— Horizontal Motor — Adam — Four-cylinder type — E^nz. 

Eoerting-Xiieckfeldt. — Next to the Otto, no gas engine is so 
popular or so extensively made in Germany as the Koerting- 
Lieckfeldt. It was first brought out in 1879, and is, therefore, 
one of the oldest surviving gas motors. Since then many im- 
provements have been introduced, and the mechanical details 
are constantly undergoing alterations. It has been shown with 
successive modifications at nearly every exhibition during the 
last ten years. Nevertheless there are two or three important 
and original features which re-appear in the different types with 
scarcely any variation. The chief of these are the vertical dis- 
position of the cylinder, the method of ignition, and the regulation 
of the speed. 

The principal advantages of vertical gas engines consist in the 
smaller floor space occupied as compared with horizontal motors, 
their smaller weight and greater simplicity. For this reason, 
since space is often of importance, various attempts have been 
made to utilise the vertical type, and make it work satisfactorily. 
Of these the most successful is the Koerting-Lieckfeldt, but, 
in common with all other motors of this class, it has some 
defects. Engines with vertical cylinders have not generally been 
found practical for larger powers, while for medium and small 
powers there is a good deal of vibration at high speeds. If a 
motor giving more than about 10 H.P. is required, either a 
second cylinder must be added, or the engine made horizontal. 

The method of ignition in this engine is by propagation of 



164 GAS ENGINES. 

flame in a special conical tube. At the time of its firat intro- 
duction by MM. Koerting and Lieckfeldt it was a novel idea, 
though it has since been extensively copied. It is based on the 
principle described in the following terms by M. Chauveau : — 
'' If a certain volume of gas communicates through a conical tube 
with the atmosphere, its largest diameter being open to the air, 
and if the gas be allowed to escape at a certain speed, the 
pressure in the tube decreases towards the mouth, where it will 
be about equal to the atmosphere. If the gas as it issues from 
the tube be ignited, the flame will spread back to the point where 
its speed of propagation equals the velocity at which the gas 
is escaping. Here it will remain stationary unless, at a given 
moment, the mouth of tlie tube be suddenly closed, when the 
remainder of the gas will ignite, and a jet of flame be projected 
into it.'* The principle has been utilised with excellent results 
to ignite the gases in this engine, though ordinary hot tube 
jgnition is also employed. 

The third novelty introduced is the method of regulating the 
•speed. If the normal number of revolutions be exceeded, the 
governor acts upon a lever, one end of which keeps the exhaust 
valve open, while the other holds a return valve in the mixing 
chamber closed. To govern the speed by thus acting on the 
exhaust, is only applicable where the gas and air are admitted 
through an automatic lift valve. It is the vacuum caused by 
the discharge of the gases which lifts the admission valve, and 
allows a fresh charge of gas and air to enter. If a return valve 
is used, to prevent the ignited gases from striking back into the 
mixing chamber, it acts only during the pressure of explosion, 
and does not lift if the exhaust be held open by the governor. 
To make it close more securely, liowever, the inventors of this 
engine have added a lever to hold it down. The result is, that 
not only pure air, but the discharged products are drawn into 
the cylinder at the next stroke, and this continues till the speed 
is reduced, and the governor releases the exhaust valve. 

There have been two distinct periods in the construction of the 
Koerting-Lieckfeldt engina In the original type of 1881 an. 
auxiliary pump was introduced, the four operations of admis- 
sion, compression, explosion plus expansion, and exhaust were 
divided, as in the Clerk engine, between the two cylinders, 
and an impulse obtained at ^ery revolution. The two vertical 
cylinders (pump and motor) were placed side by side, the 
motor piston working upwards on to the first crank on the 
main shaft, the pump being driven by a second crank on this 
shaft. Between the two cylinders was an automatic lift valve, 
a return valve, and the ignition chamber, all similar in con- 
struction and arrangement to those in the present engine. The 
exhaust valve was on the opposite side of the motor cylinder. 
The down stroke of the pump compressed the gas and air, 



KOERTING OA8 BNGINE. 165 

and the pressure lifted the admission valve. The charge was 
driven through it, and past the return valve, and ignited in the 
lighting chamber, the force of the explosion driving up both 
pistons. The mixture expanded in the motor cylinder, doing 
positive work on the piston, while the pump drew in a fresh 
charge. Professor Schottler is of opinion that this arrangement 
must have had one disadvantage. Owing to the pressure of the 
gases in the pump, there was probably some leakage past the 
return valve, which could seldom be made sufl&ciently tight to 
prevent a portion of the flame from shooting back into it. The 
method of governing the engine was original. If the speed was 
too great, the ball governor opened communication between the 
pump and a reservoir, into which ])art of the compressed charge 
was driven, and where it remained stored up. The pump 
clearance space was thus enlarged, and its compression space 
reduced, and at the next stroke the pump drew in a smaller 
charge. This increase of the clearance space by the addition of 
the reservoir continued till the speed of the engine had fallen 
to its normal limits. The construction of this engine, drawings 
of which will be found in Schottler, has now been given up for 
that of the new type, brought out in 1888. The style of the firm 
has also changed, and it is now known as Koerting Bros., of 
Hanover ; the present engine is called the Koerting. 

Type of 1888. — In this motor the four-cycle of Beau de 
Bochas has been adopted, giving only one working stroke in 
four. There is a single motor cylinder, and in other respecta 
the engine is very similar to the familiar Otto type, except in 
the ignition and governing, and in the vertical form of the 
cylinder. Fig. 79 gives a sectional elevation, and Fig. 80 a 
sketch of the method of ignition. In Fig. 79 the organs of 
admission, distribution, ignition, and exhaust are shown, ranged 
side by side towards the bottom of the cylinder. A is the motor 
cylinder, P the piston, d the connecting-rod, working direct on 
to the crank shaft K. A.11 the valves, with the exception of the 
admission valve, which is automatic, are worked from a rocking 
shaft, u, running horizontally across the engine, and containing 
two levers. The crank shaft carries at the end a wheel e, gearing 
into another below it, /, of twice the diameter. With the latter 
revolves a second auxiliary shaft c, carrying two cams, S and Sj. 
These cams work, S^ through the iever T^^on the valve-rod R|, 
and the ignition tuwB I, S through lever v on the valve-rod R, 
lifting the exhaust once during a revolution of the shaft c, or two 
revolutions of the crank shaft. Both the valves are, therefore, 
opened once in every cycle by the cams, and closed again by 
springs. 

One valve chest encloses the valves for admission, distribution, 
and ignition. I is the ignition chamber, £ the exhaust valve. 
The air enters at H from the base of the engine, in the direction 



166 



OA8 XHOIHE8. 





s 











Fig. 79. — Koerting Engine — Sectional Elevation. 

indicated by the arrows, the eas above it, and both mix at o. 
The automatic valve N is liJt ^d by the pressure, and the gas and 
air are thoroughly combined before passing on to the cylinder. 



&OBRTING OA8 XNOIME. 



167 



It is a special feature of the Koerting engine that the oharge is 
thus said to be perfectly mixed, inst^ul of entering the cylinder 
in stratified layers, as in the Otto. As the governor acts upon 
the exhaust, instead of the gas valve, the quantity of gas and air 
entering the cylinder is always in precisely the same relative 
proportions. The charge then passes into the cylinder at a, the 
automatic admission valve N being closed, and the return valve 
M held down on its seat. As soon as the down stroke of the 
piston compresses the gases into the ignition chamber, the valve M 
rises to prevent the flames from shooting back into the mixing 
chamber. Fig. 80 gives a sketch of the method of ignition. A 
small chamber communicating with the motor cylinder is in two 
hollow divisions, the lower h fitting into the upper d. The 
larger d has an opening at the bottom, h, and a transverse groove 
above, o, opposite to which is the external flame B. The lower 
piece b usually rests upon the su[)port d' and between it and d is 
a small longitudinal space or aperture, m, forming a continuation 
of h. Enclosed within d and 6 is a cone-shaped tube in two 
parts; the upper r is solid, the lower 8 is hollow, and tapers 
towards the bottom, where it communicates 
during the compression and explosion of 
the gases with the motor cylinder through a. 
At other times the connection between the 
ignition chamber and the motor cylinder is 
shut ofl*. 8 and if are the stationary, and 
r and h the moving parts. Before the end 
of the down compression stroke, the pres- 
sure of the gases drives up 6, closing the 
passage m, while the solid cone r is lifted 
by the valve-rod R^ (Fig. 79). The lower 
piece having left its support c/p the com- 
pressed gases rush up the narrow end of 
the cone 8, and ignite at the flame B througb 
the groove o; r is now driven down by the 
cam on the auxiliary shaft and the valve- 
rod Rj, and the part h descends, leaving the 
passage m free. The mouth of the cone 
being suddenly closed, while the compressed 
gases are still entering from below, the flame 
shoots downwards until the pressures are equalised. The ignited 
gases rush out through m and A, and tire the remainder of the 
charge. The pressure of the explosion firmly closes the return 
valve M. 

Governor. — The exhaust valve E is worked by the valve- 
rod R, in the same way as the ignition valve by R^, except when 
acted upon by the governor, as shown in Fig. 81. Upon the 
auxiliary shaft c is a weight, n, revolving at the same speed 
4Ui the counter shaft round a fixed point, and held in ]>oiitiaii 




Fig. 80. 

Koerting Ignition 

Valve. 



168 



GAS ENGINES. 




by a spring, s. If the speed is normal, the weight does not 
interfere with the working of the valve, which is regularly 
opened once in every revolution of c by the cam S. But if the 
proper speed be exceeded, the weight rotates too rapidly, pro- 
jects outside the plane of the wheel, and pushes forward a bell 

crank, l, carrying a notch 
at q. This notch catches 
in a projection on the 
lever v at the moment 
when it is pushed down 
by the cam S ; the lever 
V and the valve-rod K are 
raised, and the exhaust 
valve lifted. Until the 
speed is reduced, and the 
weight sets the catch free, 
the lever cannot release 
the valve, and return to 
its original position. At 
the same time, the open- 
ing of the exhaust valve 
raises the left arm of a 
rocking lever, shown at G, 
Fig. 79, and the other arm 
holds the return valve M 
closed. No fresh charge can, therefore, enter the cylinder until 
the exhaust valve-rod being released, the lever G regains its 
position. During this time ouly the products of combustion 
will be drawn by the suction of the up stroke into the cylinder. 

In some cases the cooling jacket water is a difficulty. To 
meet this case, the inventors have introduced an apparatus for 
economising the supply, which occupies little space, and can be 
fixed against a wall near the engine. It consists of a series 
of cast-iron pipes with external ribs, into which water drawn 
from a reservoir is sent, and passed on into the cylinder jacket. 
As soon as the cylinder becomes hot this water rises into the 
upper part of the pipes, and is replaced by cooler water. Be- 
tween the pipes and ribs a circulation of air is induced, thus 
cooling the water, which can be used continuously for hours. 
The hot air is either discharged into the atmosphere, or used to 
warm the building. The oiling of the engine is effected auto- 
matically in the usual manner. 

Horizontal Type. — MM. Koerting have lately brought out 
a new horizontal motor of the usual four-cycle type. In this 
engine hot tube ignition is used with a Bunsen burner. An 
outer porcelain encloses a very small inner platinum tube, kept 
at a red heat. During the compression stroke the tube com- 
municates through a valve with the outer air, discharging the 



Fig. 81.— Koerting Governor- 
Elevation. 



KORRTINQ OAS ENGINE. 



169 




products of combustion. The velocity of the gas entering the 
ignition chamber is said to be so great, that the flame does not 



170 



GA8 SNGUTIS. 



spread back into the cylinder until the outer valve is closed, 
when it shoots forward, igniting the remainder of the charge. 
The valves resemble those of the vertical engine, except that 
they are worked by eccentrics on the crank shaft. There are 
three valves ; the first is automatic, and through it the gas and 
air enter the mixing chamber, the second admits them to the 
cylinder, the third is the exhaust. A lever acted upon by the 
pendulum governor works, as already described, between the 
exhaust and the admission valves, and as the one is lifted it 
holds the other closed. Tiie weight is carried on the eccentric 
opening the exhaust valve. If the speed becomes too great, it 
acts through levers upon a notch catching in the exhaust valve- 
rod, and prevents its closing. As the eccentrics revolve on the 
crank shaft, they would, if not prevented, open the valves at 




Fig. 82a. — Koerting Engine — End view, Valves, &c. 

every revolution, instead of every other revolution. An arrange- 
ment has, therefore, been adopted with the exhaust valve eccen- 
tric, somewhat similar to that in the Lalbin engine. A toothed 
wheel revolves on the eccentric-rod, which is made hollow, and 
contains a smaller rod within it. By means of a rotating disc 
the inner rod is made to fit successively into the liollows, or rest 
against the teeth of the wheel, and the action is communicated 
to the eccentric at every other stroke. The other eccentric acts 



ADAM GAB ENGINE. 171 

as usual, but the charge is only ignited once in every two Tevo- 
lutions. Fig. 82 gives an elevation, and Fig. 62a an end view 
of this horizontal motor. 

The Koerting-Iieckfeldt engines have been tested several 
times. Experiments were made in (Germany by Professor 
Schottler on one of the original type, with motor cylinder and 
pamp. The engine was a 3 H.P. nominal, 2*18 B.H.P., and 
showed a consumption of 45 cubic feet of gas per B.H.P. per 
hour. The new type has yielded results as favourable as those 
obtained with any other compression engine. The most im- 
portant tests were made in 188 J and 1890 by Professor Fischer. 
A 10 H.P. nominal engine gave a consumption of 23 cubic feet 
of gas per B.H.P. per hour, and the same figures were obtained 
with a 20 H.P. engine. Few gas engines up to the present time 
have worked more economically. A 1 H.P. engine tested at the 
Goiiitz Exhibition in 1888 by Professor Levicki, of Dresden, 
consumed 34 cubic feet of gas per H.P. per hour. Details of 
these and of other experiments will be found in the table, p. 402. 
MM. Koerting have not been behind others in utilising Dowson 
gas, and three of their engines, with a total of G6 H.P.' nominal, 
are driven by it at their works near Hanover. 

Adam. — The Adam gas engine, constructed by the Maschinen- 
Bau Gesellschaft, at Munich, from the patents of Mr. G. Adam, 
resembles tlie last engine in many respects. Ignition is efifected 
by propagation of flame ; the governor acts on the exhaust valve, 
and the products of combustion are re-introduced into the 
cylinder instead of a fresh charge, if the speed is too great. The 
makers of the Adam, however, claim these details as the result 
of independent invention. Like the Koerting the engine is 
vertical. The smaller sizes are single cylinder ; in the larger 
types two cylinders are used, as shown in Fig. 86. 

The Adam is of the usual four-cycle single-acting type, and there 
is one working stroke for every two revolutions. Fig. 83 gives a 
sectional elevation of a single cylinder motor. The valves are 
worked in the same way as in the Koerting by a small auxiliary 
shaft K^ driven from the crank shaft K by spur wheels two to 
one. The organs of admission, distribution, ignition, and exhaust 
are arranged side by side, and shown to the left in Fig. 83. 
Gas and air are admitted into the mixing chamber, the gas 
from above, the air from below. Tlie admission valve is conical, 
and the stream of gas is directed into a chamber, where 
it is thoroughly mixed with the air. Another automatic 
valve then lifts to admit the mixture through the wide pas- 
sage 6 at a certain pressure into the cylinder A with piston P. 
The constructors lay much stress on the width of the passage 
b, and the delivery of the gas and air at a pressure of several 
atmospheres into the cylinder. This pressure completes the 
thorough mixing of the charge, and the makers declare that. 



172 



OAS ENGINE& 



without it, the high explosion pressures and consequent increase 
in work done on the piston cannot be obtained. If the charge 
is perfectly mixed, an ignition pressure of 10 to 18 atmospheres 
is possible. The gases, already compressed, being drawn into 
the cylinder by the up stroke of the piston, the next down stroke 
drives them into the ignition chamber H, where they are ignited 
and force up the piston ; the second down stroke discharges the 



€hvT 




Fig. 83. — Adam Engine— SectioDal Elevation. 

products through the exhaust at E. The ignition-rod S and 
exhaust valve-rod Sj are driven from the auxiliary shaft Kj, and 
are kept in position by springs t and t'. 

Although the principle of ignition by propagation of the flame 
has been applied to the Adam engine, the details are worked out 
in an original manner. The ignition chamber consists of a hollow 



ADAM OAS ENGINE. 173 

tube or cylindrical valve, V, enclosed within another in which 
works a small vertical piston, p. The bottom of the outer tube 
is pierced with holes passing through into the passage b and the 
compression space of the cylinder; the top is open, and com- 
municates with an external flame B. At the moment of ignition, 
the compressed gases from the motor cylinder enter the tube 
through the passage b and the holes, while the small piston p is 
in its highest position. The down stroke of the motor piston 
drives them up the tube till they meet the flame at the opening 
d, and are ignited. The valve piston now descends, closes the 
opening d, thus shutting ofif communication between the flame B 
and the ignited gas in the tube, and drives down the cylindrical 
valve. A small orifice at the bottom, opening into the com- 
pression channel 6, is thus uncovered, and the flame, cut ofl* from 
upward progress, shoots through it into the remainder of the 
compressed gases, and rapidly ignites the whole (compare Fig. 80). 

The speed is regulated by the ball governor, which keeps the 
exhaust valve open a shorter or longer time. The governor G, 
shown in Fig. 83, at the top of the engine, actuates the valve- 
rod 8y The counter shaft K| carries two cams of different sizes 
for working the exhaust, and a hollow for the ignition valve. 
The two valve-rods end in a roller, «, just below the counter 
shaft. When the hollow in the cam is brought round to the 
rod S, working the small valve piston p, the rod is allowed 
to rise, and with it the piston, and the gases ignite. During 
the remainder of the revolution the rod and piston leave the 
hollow, and are driven down, and no ignition of the gases at 
the external flame B can take place. The exhaust valve-rod is 
usually opened once in every revolution of the counter shaft by 
the smaller cam. But if the speed be too great, the balls of the 
governor rise, and shift the roller e from the smaller to the 
larger cam. Thus the exhaust remains open during half a revo- 
lution of the shaft K^, or while the piston makes one down 
stroke (exhaust), and the next up stroke (admission of the 
charge). Meanwhile the automatic admission valve cannot rise, 
being held in position by a strong spring. The suction of the 
piston failing to draw in a fresh mixture, the gases of combus- 
tion are re-admitted, and continue to enter till the speed is 
diminished, and the roller released and transferred to the smaller 
cam. 

The constructors of the Adam have also introduced a 
twin -cylinder vertical engine for larger powers. A 25 H.P. 
motor of this kind was shown at the Munich Exhibition in 1888; 
and another of 30 nominal H.P., with four cylinders, at the 
Frankfort Electrical Exhibition in 1891. The latter was of the 
same type as the twin-cylinder engine, with double the number 
of cylinders. Fig. 84 gives a view showing a sectional eleva- 
tion, Fig. 85 a plan, oind Fig. 86 a section through one pair 



174 



6A8 ENGINES. 



of cylinders. The cylinders are placed diagonally to each other, 
and the makers consider this disposition advantageous ; the 
centre of the axis of each is in line with the centre- of the crank 
axis. The four pistons work opposite each other in pairs on to 
two cranks 180* apart, and one crank shaft ; the up stroke of 
one of the pair of pistons is always more rapid tiian the corre- 
sponding down stroke of the other. Thus the engine, instead of 
being a four-cycle, is virtually a two-cycle motor, and there is 
an explosion beneath one piston of each pair, every time it passes 
the dead point. The valves for admission, ignition, and exhaust 
are the same as in the single-cylinder engine, and are ranged at 




It j- 

-Adam Twin-Cylinder Engine — Side Elevation. 

either end, at right angles to the cylinders. Figs. 84 and 85 
show the arrangement of the parts ; the flywheel is in the centre, 
with two cylinders on each side. The admission valve is auto- 
matic, the air enters from the base of the engine, through holes, 
into the seat of the valve, the gas from the side. The dis- 
tribution valve, Fig. 84, is lifted from its seat at each stroke 



BE5V aA» BNGnrs. 



175 



of tiie piston, to admit the thorongbly mixed charge into the 
cylinder. On the left of the same drawing is shown the ignition 
valve and rod, and the method of firing the charge, which is 
similar to that in the single-cylinder engine. The ignition and 
exhaust valves are worked by rods from the small counter shaft; 
the latter runs at right angles to the crank shaft, from which 
it is driven by wheels geared in the usual way. The counter 
shaft carries cams, acting upon rollers, at the top of the exhaust 
and ignition valve-rods. There is a ball governor to each pair 
of cylinders, the action of which is the same as in the single- 
cylinder engine. 




t^^^'-^^gj^tl!;^ 







^EEIB 



ZJ 




^g. 85. — Adam Twin-Cylinder Engine. 



Fig. 86. 



The most important trial made upon an Adam gas engine was 
carried out by Professor Schroter, of Munich, in 1889. The 
twin-cylinder engine tested was of 11 brake H.P., making 174 
revolutions per minute, and showed a gas consumption of 31 cubic 
feet per B.H.P. per hour. Other and later experiments made 
upon dififerent sizes of engine up to 12 H.P. gave better results. 
Details are given in the Table of Trials. The lowest consump- 
tion of gas was obtained at Nuremberg in 1888, where, with an 
engine of 11*72 B.H.P., the consumption was 27 cubic feet of 
ga£ per B.H.P. per hour, inclusive of the external flame. 

Benz. — One of the most important and best designed of 
German engines is the Benz, patented in 1884, and constructed 
by the Rheinische Gas-Motoren Fabrik at Mannheim. In it 
the problem is again treated, how to obtain a motor impulse for 



176 



GAS ENGINES. 



every revolution, without the additional complication of a second 
pump cylinder. The loss of j)ower and want of regularity of four- 
cycle engines, giving an explosion only every two revolutions, 
is thus avoided. In the opinion of Professor Witz, the difficulty 
is more completely and satisfactorily solved in this than in any 
other engine. The chief novelty is the introduction of a charge 
of compressed air, to aid the piston, during its return stroke, in 
driving out the products of combustion. This arrangement is 



^xMtmt 




Fig. 87.— Benz Engine— Elevation. 



^niiitm 



JSoehausi 




Fig. 88.— Benz Engine— Plan. 



found to work well, but it entails a small pump to compress the 
gas, and a separate receiver, from which the compressed air is 
admitted into the cylinder. 

Fig* ^7 gives an elevation and Fig. 88 a plan of the Benz 
engine. A is the horizontal motor cylinder closed at both ends, 
in which the piston P works, A^ the small gas pump with 
plunger piston P^. The air receiver in the base of the engine B 
is shown at Fig. 87, and D is the pipe through which the 



BENZ ENOINB. 177 

compressed air passes to the cylinder. S is a slide valve, 
worked by eccentric g on the crank shaft, through which and 
the port m, the air is drawn, in the first instance, into the 
front part of the cylinder. During the next forward stroke, . 
the side of the piston next the crank compresses it into the 
receiver below, from whence a charge of compressed air enters 
the back of the cylinder through D and the lift valve a. E is the 
exhaust valve, c the electric ignition wires. The two valves a 
and E are worked from the crank shaft by an oblique rod 
indicated by dotted lines in Fig. 87, a lever, C, and a small 
oscillating cam, d^ which at a given moment pushes up the valves 
from their seat. The piston P^ of the gas pump is fixed by a 
transverse bar, ^, to the crosshead, and moves with it. The gas 
is admitted into the pump A^ through a valve connected to the 
governor, which raises it for a longer or shorter time, according 
to the speed. The return stroke of the pump compresses the 
gas into the motor cylinder, through a passage and the lift 
valve/ This valve is held down on its seat by a spring, except 
at the end of the pump stroke, when it is pushed up by the 
projection ^, acted upon by the lever n and eccentric A on the 
main shaft. For the compression of the air into the receiver the 
front part of the motor piston is utilised. Air is drawn in during 
the return stroke at the end of the cylinder nearest the crank, 
and compressed by the next forward stroke into the receiver, an 
arrangement which has been described in several other engines. 
This air is intended to act as a cushion in front of the piston, to 
keep the cylinder cool, and deaden the shock of explosion. The 
electric ignition is obtained from a small dynamo, and a Ruhm- 
korff coil. The mass of the engine is connected to the negative 
pole, the wires are insulated in a porcelain rod which projects 
into the cylinder at c, and contact between the points is 
established by levers working from the crank driving the 
exhaust and air injection valves. 

Benz Working Method. — The action of the engine is as 
follows : — The piston being at its inner dead point, and the 
compressed charge behind it, ignition follows, and the piston 
is impelled forward. The gases expand doing work, and at 
the same time the air in front of the piston is compressed 
into the receiver, and the gas pump in its forward stroke draws 
in a charge of gas. Near the end of the forward stroke the 
exhaust valve is opened at E, and the pressure instantly 
foils. Shortly after, when the energy of the flywheel has 
carried the piston over the outer dead point, the air valve at 
a is lifted, and a charge of compressed air is admitted. The 
gases of combustion are driven out before it through E, and 
the cylinder so thoroughly cleansed, that, by the time the 
piston has passed through half its stroke, nothing but air is 
lefb^ and the valves at a and E close. The piston now com- 

13 



178 GAS ENGIKES. 

presses the air in front of it, and just before the end of the 
stroke the gas admission valve at / is raised, the gas and air, 
already compressed, mingle, and at the dead point the electric 
spark fires the charge. It should be noted that this cycle 
utilises the two sides of the piston, a constant pressure is 
maintained in the air chamber, and the indraught of fresh air 
certainly helps to keep the cylinder cool. The %vhole of the 
forward stroke being spent in expansion, and the discharge, 
admission, and compression of the gases being carried out 
during the return stroke, great expansion is obtained in 
proportion to compression. The action of the engine is 
ingenious, and it is said to work well, with great regularity of 
ignitioD, owing to the purity of the charge. As, however, the 
exhaust opens shortly before the completion of the expansion 
stroke, and the pressure in the cylinder is rapidly reduced, 
expansion must to a certain extent be checked, and the gases 
discharged at a comparatively high pressure and temperature. 
It is probably due to this, and to the number of the parts, that 
the engine, notwithstanding its excellent cycle, does not work 
with great economy. 

Trials. — A series of experiments were made upon a 4 H.P. 
Benz engine at the Karlsruhe Exhibition in 1886. The mean 
number of revolutions when running full load on was 152, brake 
H.P. 5*61, and total consumption of gas per B.H.P. per hour 
25 cubic feet. The proportional consumption was considerably 
higher when running empty. A gas consumption of 23 cubic 
feet per I. H.P. per hour has been claimed for it. 



CHAPTER XIV. 
OTHER GERMAN ENGINES. 

Contents. — Daimler — Durkopp — Dresdener Gas-Motor — Kappel — Nurem- 
berg Liltzky — Berliner Ma^chinen-Bau Motor— Sombart—Capitaine. 

Daimler. — This engine is constructed by the Daimler Motoren 
Gesellschaft at Cannstadt, near Stuttgardt ; the French makers 
are MM. Panhard and Levassor at Paris. One of these curious 
engines was shown at the Paris Exhibition of 1889. It has 
several novel and interesting features, the chief of which are 
its great speed, the absence of a water jacket, and the purity 
of the charge, due to the complete expulsion of the products 
of combustion. By employing high speeds, and thoroughly 



OTHER GERMAN ENGINES. 179 

cleansing the cylinder of the burnt gases, the inventor aimed 
at producing a light, but powerful engine. The original motor 
had one cylinder ; the later type, as now made, is vertical with 
two cylinders. It was introduced in 1889, and is better designed 
and more economical than the first. 

This Daimler motor differs from most others because all the 
organs, even the flywheel, are enclosed in an air-tight metal 
casing. This casing is intended to protect the parts from dust, 
to keep in the oil, and to serve as a reservoir, into which air is 
introduced and compressed by the action of the piston. The 
horizontal shaft is below, at right angles to the axis of the 
cylinders, and passes through the centre of the casing. There are 
two cylinders and two pistons, placed diagonally at a slight 
angle above the crank shaft, and working down through two 
connecting rods upon two cranks. The explosion in one 
cylinder is sufficient to drive both cranks through one revol- 
ution. The engine is of the four-cycle type, but the operations 
of admission, compression, explosion plus expansion, and exhaust 
are performed alternately in each cylinder. The gases are 
admitted during the down stroke of the one piston, and simul- 
taneously expanded by the down stroke of the other, which is 
the working stroke. The next up stroke compresses the charge 
in one cylinder, and expels the burnt products in the other. 
Thus there is an explosion and a motor impulse in one or 
the other cylinder for each revolution, and a complete cycle 
is carried out in each cylinder during two revolutions. The 
charge is very rich, the products of combustion being completely 
expelled at each stroke. The flame spreads rapidly through the 
pure mixture, and the speed of propagation is even greater than 
the piston speed. These efiects are obtained by means of two 
special air admission valves. One of these is in the centre of 
each piston, and is lifted by forks during the up stroke, closing 
when the pressure above is greater than that below. The other 
air valve is at the side of each cylinder, and opens automatically 
to admit air from without, as soon as the air in the reservoir 
has been exhausted through the piston valves. As this reser- 
voir tills, the pistons descend, making their down stroke, and 
comi)ressing the air below them. Having reached their lower 
dead point, they begin to return, the products of combus- 
tion being behind the one, and the fresh charge behind the 
other. At this moment the piston valves are lifted. In one 
cylinder the air from below mingles with the fresh charge, and 
is further compressed ; in the other it drives out before it the 
products. 

Figs. 89 and 90 show the arrangements of the parts. A and 
Aj are the cylinders, P and P^ the motor pistons, and Cj the 
two cranks, K is the crank shaft, and B the cylindrical casing in 
which the cranks are enclosed, resting on brackets ; c and Cj are 



180 



GAS ENGINES. 



the connecting-rods. At O, Fig. 89, is the automatic valve, 
opening to admit external air into the reservoir below the 
pistons. The two piston valves V and Vj are lifted at each up 
stroke by two forks, I and Ij, to admit air from the base or 
reservoir into the upper part of the cylinder. The admission, igni- 
tion, and exhaust valves are enclosed in a valve chest, S, at the 
top of each cylinder. Admission is effected through an automatic 
valve, L, which rises as soon as the exhaust has closed and a 
vacuum is formed, and the gases pass to the cylinder through a 




Fig. 89.— Daimler Engine- 
Section. 



Fig. 90.— Daimler Engine- 
Elevation. 



wide passage, m. In tlie next up compression stroke the mixture 
is driven into the hot ignition tube J and fired, and during the 
exhaust stroke the gases are discharged through the same pa.ssnge, 
and through the exhaust valve E. In the admission and firing 
of the charge the engine does not differ much from others of the 
four-cycle type, but it has neither counter shaft nor eccentric. 
Admission and ignition are both automatically obtained by the 



OTHER GEBMikN ENGINES. 181 

suction and compression of the piston, and the exhaust is opened 
by a vertical valve-rod, R, parallel to the cylinder. 

As in most engines having an automatic admission valve, the 
speed in the Daimler is regulated by the governor acting on 
the exhaust valve, keeping it closed a longer or shorter time. 
As long as it is not opened, the pressure in the cylinder, increased 
by the compressed air from the reservoir, is sufficient to prevent 
the admission valve from rising, and admitting a fresh charge. 
The exhaust rod carries a lever with two arms, r' and r", oscil- 
lating round the fixed point r. A small projection, t, on the 
rod K fits into a groove, 5, on the disc of one of the cranks, and 
as the crank rises it lifts the valve. This groove is so contrived 
that it only meets the projection on the valve-rod, and opens the 
exhaust, . once in every two revolutions of the crank. Each 
time this, occurs, the longer of the two arms reaches and opens 
the exhaust valve. If the speed exceeds the normal limits, the 
governor G on the crank shaft pushes up a second lever, n, 
terminating in a projection, n^. Fig. 89. The projection catches 
in the arm r^ of the lever, as seen in Fig. 90, and holds it 
down. The exhaust valve not being opened, the products of 
combustion remain in the cylinder, and no fresh charge is 
admitted until the speed is again reduced, and the arm of the 
lever released. 

The speed of this engine is from 450 to 700 revolutions per 
minute, and for the power obtained it occupies a relatively small 
space. The 1 H.P. engine shown at the Paris Exhibition of 
1889 made 700 revolutions per minute, and was 2 feet 5 inches 
in height. The cylinders have no water jackets. The charge of 
cool air introduced at every down stroke into each cylinder 
probably helps to prevent over heating. The Daimler has not 
hitherto been made for larger powers. For small motors, which 
generally consume more gas than larger, it is said by the makers 
to require about 35 cubic feet of gas per hour per I. H.P. It is 
a convenient little motor, light, and easily handled, and power- 
ful for its size, on account of the great speed at which it runs. 
The casing in which it is enclosed, of course, conceals the 
parts. As they are not easily accessible, and the flywheel 
cannot be turned by hand to start the engine, a handle is fixed 
to the outside, to set it in motion. No trials on this engine 
appear to be on record. 

Diirkopp. — The Diirkopp gas engine, made by the Bielefelder 
Nahmaschinen Fabrik. is another four-cycle vertical engine for 
small powers. The cylinder, and the admission, ignition, and 
exhaust valves are in the lower part of the engine, and the con- 
necting-rod works upward on to the crank. The crank shaft is 
above, and carries on one side the flywheel and driving pulley. 
On the other is a vertical side shaft worked by wheels two to one. 
The valve chest is at the bottom, and all the valves are driven 



182 GAS ENGINES. 

hj cams. Air and gas are admitted at the side, and pass into 
the mixing chamber through a valve lifted by a cam upon the sido 
shaft. The same cam forces up a lever opening the exhaust. 
The gases of combustion are discharged through an exhaust 
valve made in two parts, larger and smaller. To obtain a more 
quiet discharge, part of the gases are allowed to escape through 
the smaller valve, before the main exhaust valve opens. Ignition 
is by a hot tube, the opening of which is uncovered by a cam 
lifting a small valve-rod. The governor is also placed on the 
counter shaft. The levers connected to the gas admission valve 
are opened by a cam once in every revolution of this shaft, but 
if the normal speed be exceeded, the balls of the governor rise, 
and shift the cam out of position. The gas valve remains closed, 
wholly or partially, until the speed is reduced, and the balls fall. 
No oil is said to be required for this engine, except for the crank 
shaft and piston-rod. 

The engine is also made with two cylinders, side by side, 
working at the same angle on to the same crank shaft, and with 
two flywheels. For larger powers, up to 200 H.P., the makers 
have introduced a horizontal type, with one or two flywheels. 
The consumption of gas is said to be from 23 to 35 cubic feet 
per I.H.P. per hour, and the engine runs from 250 to 140 revo- 
lutions per minute, according to the size. In estimating the 
economical working of foreign engines by their consumption of 
gas, it must not be forgotten that the gas produced on the Con- 
tinent has generally a lower calorific value than English gas. 

Dresdener Gas- Motor. — The gas engine lately brought out 
by the Dresdener Gas-Motoren Fabrik (Hille's patent), is a com- 
pact and handy little vertical motor, single-acting, and using 
the Beau de Rochas cycle. Like many of the smaller engines 
which have appeared since the expiration of the Otto patent, 
it adheres very closely in working details to that type. It 
has the usual sequence of operations, admission, compression, 
explosion plus expansion, and exhaust, each occupying one for- 
ward or return stroke, and there is one explosion for every two 
revolutions. The piston-rod and connecting-rod work direct on 
to the crank shaft. A slide valve at the side of the engine, 
acted on by a valve-rod from a counter shaft, effects the admis- 
sion of the gas and air and the hot tube ignition. The counter 
shaft is driven from the crank shaft in the usual way, by 
wheels, 2 to 1. The exhaust valve below the cylinder is 
opened by levers and closed by a spring, as in the Otto engine; 
it is worked from the counter shaft by a separate valve-rod. 
For small powers, from i to 6 H.P., these engines are made 
vertical, with a pendulum governor, and run at from 180 to 230 
revolutions per minute. For powers from J to 30 H.P., a hori- 
zontal single-cylinder type, making 120 to 180 revolutions per 
minute, is used, with a centrifugal governor. Where great 



OTHER GERMAN ENGINES. 183 

regularity is required, as for electric lighting, the engines have 
two cylinders, are made in sizes from 3 to 60 Brake H.P., and 
run at a speed of 150 to 200 revolutions per minute. 

KappeL — The Maschinen Fabrik Kappel at Chemnitz, Saxony, 
have introduced a gas engine similar in many respects to the 
Otto. It is a single-cylinder horizontal engine, single acting, 
and is made for powers from 2 to 6 Brake H.P. The hot tube 
ignition is worked by a small slide valve ; the admission of gas 
and air, and discharge of the exhaust gases are effected by 
ordinary lift valves. All these organs are driven from a counter 
shaft parallel to the crank shaft, and worked from it by 
wheels in the usual proportion. The speed is regulated by a 
spring governor. The engine runs at 170 revolutions per 
minute. By merely adjusting a screw, the number of revolu- 
tions can be greatly increased or diminished while the engine is 
running, which is sometimes desirable. The engine stands upon 
a strong cast-iron base, and is said to be noiseless in action. 
Another single cylinder type is made in sizes from 1 to 12 H.P. 
nominal, and runs at 140 to 180 revolutions per minute. The 
consumption of gas in both the Kappel and the Dresden-Hille 
engines, as given by the makers, is from 23 to 35 cubic feet per 
hour per H.P., according to the size of the engine. They do 
not appear to have been hitherto tested by experts. 

Iiiitzky. — The Nuremberg gas engine, designed on the LUtzky 
system, is an interesting little motor, differing in several respects 
from the usual type. It is vertical, with the cylinder at the top, 
the piston working down through a connecting-rod upon the 
crank shaft, placed in a hollow conical base plate below. There 
are two flywheels, and the inventor asserts that the engine 
combines the stability of a horizontal, with the compactne.ss of a 
vertical motor. The valve gear is reduced to a minimum, and 
there is neither counter shaft nor eccentric. Admission is by 
two automatic lift valves at the top of the cylinder. Through 
the first the gas passes into the mixing cliamber, the second rises 
to admit the charge of gas and air into the cylinder, but the two 
are so connected by levers that the admission valve can fall, but 
cannot rise without raising the gas valve. The exhaust valve 
at the side of the cylinder is worked by levers and a cam 
on a small counter shaft, driven from the crank shaft by spur 
wheels, 2 to 1. The pressure of the gases prevents the gas 
admission valve from rising while the exhaust is open. The 
speed is regulated by a pendulum governor on the crank shaft, 
as in the Simplex engine. If the speed be normal, the lower 
heavier weight at the bottom of the pendulum is pushed 
outwards at every stroke by an eccentric on the shaft, and 
returning, releases the levers opening the exhaust from a notch* 
on a disc, and the valve closes. But if the speed be too great, 
the pendulum weight does not strike against the eccentric in 



184 OAS ENGINES. 

time, the levers remain fixed in the notch, the exhaust is held 
open, and the gas admission valve cannot rise. 

A 6 H.P. LUtzky engine was tested by Professor Schottler in 
Germany. When running without the governor at a mean speed 
of 200 revolutions per minute, the consumption of gas was 
24 cubic feet per hour per H.P. When the governor was put 
on, the engine made 180 revolutions per minute, and the con- 
sumption at half power was 28 cubic feet per hour per H.P. 
The gas used was exceptionally rich. Good drawings of this 
engine will be found in the Zeitschrifi des Vereines Deutscher 
Ingenieure, August 22, 1891. It is made in sizes from 1 to 10 
Brake H.P., and runs at 180 revolutions per minute. 

Berliner Maschinen-Bau Motor. — The gas engine made by 
the Berliner Maschinen-Bau Gesellschaft, in sizes from 1 to 30 
B.H.P., is of the usual four-cycle horizontal Otto type, and 
stands on a strong foundation. Hot tube ignition is used, 
there are no slide valves, and the valves for admission and 
exhaust are worked by a counter shaft, at right angles to and 
driven from the crank shaft. A sensitive centrifugal governor 
regulates the quantity of gas automatically, according to the 
power required. The consumption is said to vary with the size 
of the engine from 23 to 35 cubic feet of gas per hour per I.H.P., 
and the average speed is from 200 to 160 revolutions per minute. 

Sombart. — The Sombart engine, made by the firm of Buss, 
Sombart <k Cie., of Magdeburg, and first exhibited in 1886, is 
one of the older motors, still retaining the original vertical type, 
and in which the charge is admitted and fired through a slide 
valve. In some respects it resembles the Adam and the 
Koerting, and the ordinary four-cycle is used. The admission 
and exhaust valves were formerly driven by spur wheels, 2 to 1, 
on the crank shaft; they are now worked by an eccentric on 
the same shaft. The gas aod air are admitted through a slide 
valve acted on by a rod from this eccentric, the exhaust is 
opened from it by means of a roller and levers. Ignition is 
obtained in the same way as in the Wittig & Hees engine 
(see p. 64), by the propagation of an external flame through a 
passage in the slide valve. The pressure is equalised and the 
flame protected in a special manner, fully explained in the 
description of that engine. Fig. 91 gives a vertical section, and 
Fig. 92 a plan of the Sombart engine ignition, showing the 
covering over the internal flame, shaped like an extinguisher, 
and the small channel through which it is fed with compressed 
gas from the cylinder. The air enters through a trumpet-shaped 
opening, the mouth of which is closed and admission effected 
through holes round the circumference; by this arrangement 
the air is said to be drawn in noiselessly. The engine is 
controlled by an inertia governor, acting by the partial or total 
suppression of gas. In a tiial by the makers, the consumption 



OTHER GERMAN ENGINES. 



185 



of a 3-6 H.P. engine was 30 cubic feet of gas per H.P. per 
hour ; the gas used was of poor quality. 

MM. Buss and Sombart lay much stress upon two points, in 
the construction and working of their engine. In common with 
others who have given attention to the subject, they maintain 
that it is more advantageous to run a gas engine at a compara- 
tively low speed, and that the gain in power, obtained by increas- 
ing the number of revolutions, is counterbalanced by the wear 
and tear, and the greater consumption of gas and oil. Few of 
their engines are intended to be driven at more than 150 revolu- 
tions per minute. They consider also that vertical engines give 
less piston friction, and are better in most respects than horizon- 
tal, and in this opinion most German makers of gas motors appear 
to concur. The Sombart engines are said to run with great 





Fig. 91.— Sombart Engine 
Ignition Valve — Vertical Section. 



Fig. 92. — Sombart Enffine 
Ignition Valve — Horizontal Section, 



regularity, owing to the large size of the piston, and length of 
the connecting-rod in proportion to the stroke. They are made 
in sizes from 1 to 12 B.H.P., and run at 150 to 180 revolutions 
per minute. Drawings of the earlier type will bo found in 
Schottler, and of the modern type in Witz ; in the latter hot 
tube ignition is used. 

Capitaine. (Theory.)— Among engines recently introduced, 
an interesting and original little motor is the small vertical Capi- 
taine. The inventor, Herr Emil Capitaine, is opposed in opinion 
to MM. Buss and Sombart, as regards the relative values of high 
and low speeds. In a paper communicated to the Verein deut- 
scher Ingenieure (vol. xxxiv. of the Zeitachrift) he maintains that 
the greater the number of revolutions, the better results will be 



186 GAB ENGINES. 

obtained. At tlie same time he advance!) the novel point, that 
the piston speed may be quite different from, and independent 
of, the speed of expansion of the gases. Though usually classed 
together, the two are not synonymous, and their effect is by no 
means the same. If an engine be constructed, running at a 
certain speed, with a small diameter of cylinder and a long 
stroke, the speed of the piston will be considerable, and the 
speed of expansion relatively small. On the other hand, if 
another engine, going at the same speed, have a short stroke 
and a large diameter of cylinder, the piston speed will be rela- 
tively small, and the speed of expansion greater. Combustion, 
however, can never be instantaneous, and, therefore, the speed 
of the piston should be limited to the rate of combustion of the 
charge. The Otto engine owes its success partly to the carefully 
designed ratio between combustion and the speed at which the 
gases expand. To every speed of revolution in a gas engine, a 
certain rate of combustion corresponds. Hitherto attempts to 
increase the efficiency have been made by — 1, More or less rapid 
combustion ; 2, Raising the temperature of the cylinder walls ; 
3, More ])erfect expansion of the gases ; 4, More complete ex- 
pulsion of the products of combustion; 5, Greater compression. 
All these improvements, combined with a suitable rate of 
/ combustion, have yielded good experimental results. Herr 
Capitaine is himself of opinion that, to obtain greater economy 
in a gas engine, expansion ought to be more rapid, and explosion 
practically instantaneous ; the diameter of the cylinder should 
be increased, and the stroke shortened. 

The disadvantages of running at high speed are — 1, More 
rapid wear and tear ; 2, Uncertain ignition ; 3, Incomplete 
combustion; and 4, Vibration. Against these drawbacks Herr 
Capitaine sets the gain of reduction in size and cost. If an 
engine can be made, without overheating, to run at twice as many 
revolutions per minute as another, its dimensions may be smaller, 
it will be lighter, less expensive, and the cost of transport smaller. 
Hitherto when engines have been tested at high speeds, no great 
gain in economy has been observed. Being constructed to run 
at a given number of revolutions per minute, and their ports pro- 
portioned to this speed, and to a given rate of combustion, they 
cannot be expected to work as efficiently, when they are driven 
at a much higher speed. The whole of the charge cannot reach 
the igniting chamber of the cylinder at the moment of explosion; 
part of it is ignited afterwards, and expands too late to act use- 
fully on the piston. Herr Capitaine found, when testing an 
engine constructed to run at a high speed that, when making 
320 revolutions per minute, an excellent indicator diagram was 
obtained. When the speed was increased to 800 revolutions, 
the efficiency was much lower, and diminished in proportion to 
the increase of speed. The number of revolutions should not 



OTHER OBBMAir BHOINES. 187 

be in excess either of the speed of propagation of the flame, or 
the development of pressure in the gas.* 

Capitaine Engine. — In the Capitaine the piston speed is the 
same as in other motors, but the number of revolutions, or speed 
of expansion of the gases, is doubled. Another distinctive 
feature claimed for this engine is that, by an ingenious arrange- 
ment of the admission port, the incoming charge is kept apart 
from the products of combustion, and not allowed to mingle 
with them. The engine is of the single-acting vertical type ; 
a sectional elevation is shown at Fig. 93. The disposition of 
the valves and working parts is similar to that of the Liitzky 
engine. The cylinder A is at the top, and the piston P works 
down upon the crank shaft K, which, with the flywheel, is 
below. Gas and air are admitted from above through a double- 
seated automatic lift valve. The air enters at D and passes 
down into the wide port through the bottom of the valve at c, 
the gas through the upper seat of the valve at /. The top and 
bottom of the valve are connected by a spring, 8, and work 
independently. Before passing through c into the cylinder, the 
gas and air mingle in the annular chamber formed by the valve, 
which imparts to them a circular motion of considerable velocity. 
They next impinge against a projection, g, and the wide diameter 
of the port checks their velocity, and forces them to enter the 
cylinder in a steady stream. This is the method also employed 
to prevent the fresh charge from mixing with the gases of com- 
bustion, which are discharged through the exhaust port at the 
side E. 

The piston having drawn in the charge, the up compre.ssion 
stroke drives it into the hot ignition tube B. This tube is made 
of porcelain, which is said to afford more resistance than any 
other substance to the heat and the high pressure, and is more 
easily kept at an equal temperature. In its passage through the 
admission port, a portion of the incoming charge is directed at 
once into the ignition chamber. As there is no timing valve the 
gases enter freely, and the mixture is supposed to ignite more 
readily because part of it is already in contact with the hot 
ignition tube. The exhaust valve E is driven by a rod from an 
eccentric, H, on the crank shaft. Above the termination of this 
rod is a hollow lever, into which the projecting end of the exhaust • 
spindle tits at every revolution. But it is only at every other 
revolution that a second lever is interposed between them, and 
the eccentric, pushing up both levers, reaches and opens the 
exhaust valve. 

The ordinary four-cycle is used in this engine. The centri- 
fugal governor G is on the crank shaft, and acts through a 

• See on the Rubject of speed in Gas Engines the summary of Dr. Slaby's 
ez])eriments, in Appendix, p. 389. 



188 



J3 




Fig. 93. — Capitaine Engine — Sectional Elevation. 



OA8 PRODUCTION FOR MOTIVE POWER. 189 

rod, r, and a catch on the lever opening the exhaust. If the 
speed be too great the balls rise and draw the rod outwards. 
The knife edge of the lever misses the catch, the exhaust valve 
remains open, and no fresh charge can enter the cylinder, 
till the speed is again reduced within normal limits. All the 
wearing parts in this motor are carefully designed, wide and 
large. It is one of the newest engines, and has not yet been 
tested by experts. The inventor claims a considerable economy 
in the consumption of gus. In a trial on a 3*36 B.H.P. engine, 
with a cylinder diameter of 6*6 inches, and 6 '4 inches stroke, 
and making 300 revolutions per minute, 27*4 cubic feet of gas 
were used per B.H.P. per hour. The usual speed of the engine 
is 360 revolutions per minute. 

The makers have introduced a special water tank, for use 
where there is a difficulty in obtaining a sufficient supply for 
the jacket. The water circulates continually from the tank to 
the jacket of the cylinder and back again, and it is kept cool 
by a small fan. The engine was exhibited at the Crystal 
Palace Electric Exhibition, 1892, by the English Capitaine 
Manu&cturing Company. A motor of the same type has been 
introduced for working with petroleum, and is described in 
Part II. 



CHAPTER XV. 
GAS PRODUCTION FOR MOTIVE POWER. 

Contents. — Gaseous Fuel— Natural Gaa— Coal (J as— Distillation — ^Combus- 
tion — Bischof's System for Generating Gas — Thomas and Laurent — 
Kirkham — Siemens — Pascal — Tessi^ d u Motay — Strong — Lowe — 
Wilson — Lencauchez — ]5ow8on. 

The first attempts to produce gas from coal were made as an 
experiment to obtain light, without any intention of utilising it 
as a motive force. The process of extraction was too costly for 
the gas to be employed to drive the motors invented at the 
beginning of the century, and many were the devices described 
by the patentees, to obtain a suitable explosive gas. In one of 
the earliest gas engines, brought out by SStreet in 1794, he pro- 
posed to generate a gas to act on a piston by sprinkling a few 
drops of petroleum or turpentine on the bottom of a cylinder 
kept at a red heat. The liquid was evaporated, exploded, and 
drove up the piston. Barber obtained gas for driving his engine 
by heating coal, wood, <kc., in a retort, according to the method 
now practised in gas works. The ])rocess of making gas was 
in its infancy, carried out only in large towns and cities, and 



190 OAS EKOIKE8. 

there was much prejudice against it. It whs also very dear. 
Practically in those days there was no gas to be had, and it was 
impossible to produce it cheaply, for driving small motors. 

Gktseoiis Fuel. — As a fuel, however, coal gas was used long 
before its advantages as a motive force were perceived. During 
the first half of the century, as soon as the great value of steam 
was recognised, the economical use of coal became an important 
question. Without fuel, steam could not be generated, but 
althou,£[h this is still usually done by burning coal under a boiler, 
it has long V>een known that it is rather wasteful. It is difficult 
by <lirect combustion to obtain temperatures as high as when 
gases previously extracted from the fuel are burnt. For chemical 
purposes, where great heat is required, gaseous fuel has been in 
use for many years. Cheap gas, made in producers or generators, 
is now extensively employed in the manufacture of iron and steel, 
and other metallurgical processes, as being better and cheaper 
than burning the coal itself. A fresh stimulus was given to its 
production as soon as gas engines began to attract public notice 
and favour. It was seen that the maximum economy in driving 
them could never be attained, as long as they were worked with 
town gas, and inventors have for twenty years laboured to pro- 
duce a cheaper and equally efficient gas. 

Tliere are many ways of extracting gas from fuel. The com- 
position of diffonrnt gases will be found in Cha])ter XVII., and 
it is only necessary here to mention, without going into details, 
the ditferent methods by which it is obtained. These consist in 
bringing together, with or without combustion, the chemical 
constituents of tl^e coal and air, carbon, oxygen, hydrogen and 
their compounds. If the hot fuel is moistened with water or 
steam, the quantity of hydrogen is increased ; if air be intro- 
duced, a much greater amount of oxygen is added. In either 
case the carbon in the fuel unites with the oxygen of the air 
or of the water, and more carbonic oxide and carbonic acid 
are produced, than when the gas is formed from the chemical 
elements contained in the coal only. If the fuel is burnt in a 
closed vessel, and steam added and evaporated, the gas produced . 
is richer in hydi-ogen than if air is admitted. v\ hen air is 
introduced, the same process takes place, but instead of hydro- 
gen being liberated, there is a large residuum of inert and 
useless nitrogen. 

Gaseous luel may be divided into four classes, namely : I. 
Natural gas. II. Oil gas, obtained from petroleum, vegetable 
oil and refuse, shale, fat, resin, &c. III. Carburetted air, or air 
saturated with volatile spirit. IV. Gas extracted from coal, 
wood, peat, and other varieties of fuel, either by distillation, or 
with the addition of air or water. In the latter case it is called 
poor or water gas, or producer gas. We will now proceed to 
consider generally these four methods of gas making. 



GAS PRODUCnON FOR MOTIVE POWER. 191 

T. Hstniral Obb. — The process of generating gas from coal, or 
from the vegetable substance which forms the basis of coal, is 
crtrried on by Nature as well as by man, though on an infinitely 
larger and slower scale. The gas is produced by the heat of the 
earth and the slow combustion of chemical decomposition. Gases 
exhaled from swamps and commonly known as "will o' the wisp" 
or marsh gas, are only a variety of lighting gas, which when 
artificially produced contains about 40 |)er cent, of marsh gas. 
As the decaying vegetation of swamps, bogs, and forests under- 
goes further decomposition or slow combustion, a fresh layer of 
soil is formed over it, and it passes very gradually during ages. 
of time through the stages of peat, lignite, brown coal, and 
eventually to coal. Time, the earth's heat, decomposition and 
oxidation, and pressure, frequently cause the escape into the 
atmosphere of the gases thus generated. Of this the disastrous 
explosions in mines iifford an example. Marsh gas or carbonic 
oxide (usually termed "fire damp" or "choke damp") distilled, so 
to speak, from coal, and at a high pressure, are liberated by 
excavation, and rush into the mine workings, often with fatal 
consequences. Where the gases find a natural outlet at the 
surface through fissures in the ground, as in many places in 
North America, and in Russia along the shores of the Caspian 
Sea, they are given off from the earth harmlessly. This natural 
gas, consisting almost entirely of marsh gas, is of excellent 
quality for lighting and heating purposes, and contains more 
caloric than artificially made gas. Formerly it was allowed to 
escape to waste, but it is now partially utilised, and furnishes 
the greater part of the lighting gas used in several towns of 
the United States. 

II. and III. The methods of producing gas from oil, and of 
charging air with petroleum spirit (carburetted air), will be 
described in the second part of this work. 

IV. Coal GkuB. — The gas used for lighting and heating is 
extracted from coal in two ways, either by — 

1. Distillation, or the application of external heat to the coal. 

2. Combustion, or actual ignition of the coal. 

Distillation produces a much richer gas, and is the process, 
universally used in gas works. The cheaper and inferior kinds 
of gas, such as water or j)roducer gas, are obtained i'rom com- 
bustion. These are employed as fuel instead of coal, and to 
drive gas engines. Professor Witz draws a further distinction 
between hot and cold distillation ; the latter is chiefly employed 
for carburetted air, 

1. Distillation of Coal. — The earliest method of obtaining 
gas from coal, first practised by Murdoch, was to heat the coal in 
closed i-etorts and distil the gas from it. By this process the 
gases are given oflT, leaving a residuum of coke, &c. As the air 
is carefully excluded, the distilled products contain no gases 



192 OAS ENGINES. 

except those already in the coal. Roughly speaking, two-thirds 
of the constituents are hydrogen, carbon, and their combina- 
tions. It is only of late years, since gas motors have been 
made for larger powers, that the need of a cheap substitute for 
this distilled or town gas has been felt. As long as it was 
required only for illumination, the quantity used by each con- 
sumer was too small, to make economy of production an impor- 
tant question. As far as the heating value of town gas is con- 
cerned, it is well suited for driving a motor, but it is unneces- 
sarily pure for tliis purpose, and the price per 1,000 cubic feet 
is relatively great To produce town gas separately for driving 
small motors is, of course, impracticable, on account of the cost 
of production, &c. For some time, therefore, much attention 
has been paid to the production of a cheaper gas, less pure, but 
not liable to deposit carbon in the passages and ports of a 
motor. 

2. Combustion of Coal. — The second method of manufac- 
turing gas is by burning the coal, and three processes are em- 
ployed, each producing a different kind of gas. In all of them, 
ordinary atmospheric air is required to assist combustion. 

In the first process a forced air blast is used. The gases are 
rapidly generated by driving a current of air through the glow- 
ing coal, and combustion is thus stimulated. This furnishes 
what is called producer gas, and sometimes Siemens' gas, because 
it was first introduced by Sir Williaiu Siemens, as a fuel and 
substitute for solid coal. This gas is often used for heating 
purposes, but is not rich enough to drive a gas motor. 

The next kind is known as water gas. Here the method 
followed is also to burn the coal, and when it is in a state of 
incandescence, a jet of steam is injected into it. The steam 
is decomposed into oxygen and hydrogen, which recombine with 
the gases from the coal. The carbon present unites with the 
oxygen, and forms carbonic oxide and carbonic acid. A very 
rich gas is thus produced, which contains a larger percentage of 
the heat in the coal than gas made on any other system. 
Water gas is much used in America as fuel, instead of ordinary 
coal, because anthracite, from which it is made, is cheap 
and abundant. One disadvantage of this method is that the 
gas cannot be continuously produced. The blast of steam lowers 
the temperature of the coal, and, after an interval of about ten 
minutes, there is not enough heat to cause decomposition and 
recombination of the chemical elements forming the gas. The 
process of injection is then stopped for a time, and air instead of 
steam introduced to revive combustion. As a rule, water gas 
and producer gas are made alternately in the same apparatus. 

The third system is a combination of the two preceding 
methods. Instead of alternately injecting steam and air into 
the mass of incandescent fuel, both are admitted together. The 



GAS PRODUCTION FOR MOTIVE POWER. 193 

jet of steam carries with it, into the fuel, a current of air duly 
proportioned, and the gas, though poorer in quality, can be made 
continuously. Hitherto there have only been two applications 
of this system known to the author. About sixteen years ago 
it was first brought out and patented in England by Mr. J. 
Emerson Dowson, and the value of Dowson gas for driving 
motors is now fully recognised. About the year 1887 another 
method was introduced in France by M, Lencauchez. These 
three last kinds of gas are chiefly made from anthracite or coke. 
If ordinary coal is used, the tar, ammonia, and other residual 
products impoverish the gas, and are rather difficult to get rid 
of. Another characteristic of these cheap gases is that they 
contain a much larger quantity of carbonic oxide than town 
gas. Carbonic oxide is highly poisonous, but has no smell, and 
care is needed in using it, to prevent any escape. 

Bischof. — The earliest attempts to obtain gas for heating 
purposes from the combustion of coal, instead of from distil- 
lation, were made by Bischof in 1839. Peat fuel was burnt 
in a brick chamber, air at atmospheric pressure was admitted 
from below, through holes in the covering of the ashpit, and the 
gases generated during combustion were drawn off through a 
chimney and damper from the top of the furnace chamber. In 
1840 Ebelmen made a furnace for generating gases, worked by a 
blast of air, and a much larger quantity of gas was produced by 
this means than in Bischof s apparatus. 

Thomas and Laurent. — But the merit of being the first to de- 
sign a practical gas producer belongs to MM. Thomas and Laurent, 
who, between 1838 and 1841, constructed a gas generating 
furnace, in which many modern improvements were anticipated. 
Air compressed by a blower was admitted at the bottom of a 
fiimace, and the decomposition of the air was assisted by the 
injection of superheated steam, in the proportion by weight of 35 
of air to 1 of steam. The height of the generator was sufficient 
to cause all the oxygen of the air to be transformed into carbonic 
oxide. The fuel used was charcoal, wood, peat, coke, and 
anthracite. 

Kirkham. — Another remarkable apparatus was brought out 
in 1852 by Messrs. Kirkham, who, working independently but 
on the same lines as Thomas and Laurent, produced their gas by 
the direct combustion of the fuel in a furnace, instead of by apply- 
ing external heat to the coal, and distilling the gas from it. They 
were the first to use what is called the "intermittent" system 
of gas making — that is, the alternate admission of steam and air 
to the coal. The fuel being kindled in the generator, a blast of 
air was turned into it, until combustion was thoroughly estab- 
lished ; the air was then shut off, and steam was injected and 
quickly decomposed by the heat. After a short time the admis- 
sion of steam was stopped, and air again introduced to revive 

13 



194 GAS ENGINES. 

combustion. Other gas producers were brought out by Ekmana 
in Sweden about 1845, Beaufum^ in France in 1856, and Benson 
in 1869. In most of these early efforts, the object was not so 
much to generate lighting or heating gas from coal, as to utilise 
the waste gases from furnaces. 

aiemens. — Several important gas producers were introduced 
with successive improvements by Sir W. Siemens, who gave his 
attention to the subject as early as 1861. His main object was 
to produce a gas which could be used as a substitute for ordinary 
fuel in furnaces, and he was the first to bring the question of 
gaseous fuel prominently forward. Jn his producer a very slow 
draught of air and slow rate of combustion are employed, and 
the gases are cooled as they leave the generator. His designs 
have since been perfected, and the Siemens' improved gas 
generator is now largely used for all sorts of metallurgical and 
manufacturing purposes. The two forms of gas producers in- 
troduced into France by Minary in 1868, and his later recent 
apparatus were invented with the same object, of replacing solid 
fuel in furnaces. A useful little generator was brought out by 
Dr. Kidd in 1875, intended to provide a cheap gas for domestic 
use and cooking. With the exception of the Siemens' apparatus 
these were all on a small scale, and none of them were originally 
intended to generate gas for working motors. 

Pascal. — Pascal in 1861 was the first to develop the ideas of 
Thomas and Laurent, and those of Kirkham, and to test prac- 
tically a system for manufacturing cheap gas, by the addition of 
steam and air to the incandescent fuel. Except in its application, 
his method differed little from theirs. A cylindncal gas gener- 
ator filled with coal was surrounded by a boiler with which it 
communicated. The coal was fired, and steam from the boiler 
admitted alternately with air from a blower, worked by the 
motor. Pascal's system of making gas has long been discon- 
tinued. 

Tessie du Motay. — Another method bi-ought out by M. Tessie 
du Motay in 1871 is still used in America, in the Municipal Gas 
Works, New York. A brick furnace, enclosed in a wrought-iron 
cylindrical shell, is charged with fuel from above, and the 
gas drawn off through an annular space at the top. Air is 
introduced through a blast pipe running across the centre of the 
furnace, and the ashes and clinker are discharged below. This 
is said to be one of the best of the intermittent gas producers, 
and is simple and efficient. 

These different generators exhibit the successive steps in the 
production of gas from coal. The first improvement on the 
])rocess of distillation was the substitution of internal for external 
combustion. Instead of the outward application of heat, the fiiel 
was burnt in the furnace, and the gas led off from it in pipes. A 
blast of air was next introduced, to accelerate the production of 



GAS PRODUCTION FOR MOTIVE POWER. 



195 



{^as ; the last and perhaps the most important innovation was 
the addition of a jet of steam. This water gas has been applied 
with good results to drive a 6 H.P. Otto engine. In a trial 
extending over several days it was found that the working cost 
was four-tenths of a ])enny per H.P. per hour, and in other 
respects the engine worked satisfactorily. More gas was used 
than when coal gas was employed, but the price of generating it 
was much lower. The comparative economy of the two gases^ 
taking the mean cost of production in both cases, was 0*84 of a 
penny per H.P. per hour when driving the engine with coal gas^ 
and 0-25 of a penny with water gas. 

Cheap Gas. — The great cost of working the Lenoir engine- 
gave a fresh stimulus to the production of cheap gas. About 
1862 two systems were proposed on the Continent for making 
water and generator gas. In the first, designed by M. Tr^bouillet,, 
retorts filled with charcoal were brought to a red heat, and super- 
heated steam forced through them. Charcoal was also used in 
the other method, invented by M. Arbos of Barcelona. The 
generator was in two divisions. The upper part contained 
water, and formed a kind of boiler and superheater. The steam 
mixed with air was admitted at the bottom of the furnace. 
Neither system was applicable to the Lenoir engine, which 
required about 100 cubic feet of gas with a calorific value or 
21,978 B.T.U. (British Thermal units) per H.P. per hour. 

Strong. — Two systems, the Strong and the Lowe, for making* 
cheap gas by admitting steam and air intermittently into burning 



Side Elevation, 





Fig. 94. — Strong Gas Producer. 



fuel, were introduced about 1874. Both are of American origin^ 
and are now often used, especially in America and Germany. 
Fig. 94 gives a view of the Strong apparatus, and shows the- 



196 GAS ENGINES. 

method of generating and purifying the gas, and superheating 
the steam before it enters the furnace. A is the generator lilled 
with anthracite or coke, charged through the hopper H above, 
or through the doors /?, p. I and J are the heating chambers, 
loosely stacked with fire bricks. A forced blast of air entera 
at B below the furnace, and another current is admitted at C. 
As soon as the coal is kindled in A the air blast from B 
causes active combustion, and the gases generated are driven 
into the first chamber I. Meeting here the draught of air from 
C they are forced down through the fire bricks, and up in the 
direction of the arrows through the second chamber J till they 
reach the reservoir R, As soon as the fuel in the furnace A, 
and the bricks in the chambers I and J are at a red heat, the air 
is shut off from the blast pipe B, and the opening C, and steam 
introduced at G passes through the chambers and the furnace in 
the reverse direction to the air. In its passage through the red- 
hot fire brick it becomes superheated. At the top of the furnace 
finely-powdered fuel is sprinkled into the steam. Brought in 
contact with this coal dust continuously fed from the hopper by 
means of a slow moving Archimedean screw, the steam instantly 
separates into its elements, and these combine with the carbon 
to form rich water gas, which is drawn off at D. After a few 
minutes combustion slackens, and the process is reversed. The 
steam is shut off, the forced blast of air again admitted, and pro- 
ducer gas given off. The Strong gas is specially adapted for 
heating. It is perhaps the best of the producers working on 
the intermittent system, and generating gas alternately from 
air and from steam. 

Lowe. — The Lowe process resembles the Strong in several 
respects, and contains a generator and a single superheating 
chamber ; in the latter the gases given off during combustion 
are heated, instead of the steam. The producer is worked 
intermittently. By the side of the iron cased brick generator 
furnace is a superheating chamber filled with loose bricks, a 
reservoir of water, and a scrubber for purifying the gases. The 
generator being charged with anthracite, combustion is started 
by a blast of air. The hot gases given off rise to the top of the 
generator, and are conveyed through a pipe to the lower part of 
the superheater, where a fresh current of air is admitted, 
kindling the gases, and causing the flames to rise through the 
loosely stacked bricks. As soon as the bricks and the coals in 
the generator are at a red heat, the air is shut off and super- 
heated steam blown into the furnace. A small stream of 
petroleum drops from above on to the glowing fuel, and as 
the gases produced by the decomposition of the steam pass 
upwards through the generator, the volatilised oil mixes with 
them and forms hydrocarbons. The gases next pass through 
the superheating chamber, which being always maintained at a 



GAS PRODUCTION FOR MOTIVE POWER. 197 

constant heat, the composition of the gases is always uniform. 
They are then purified by jwissing through the water tank and 
the scrubbing chamber filled with wet coke. The gas produced 
by the Lowe system differs is some respects from others, and the 
inventor asserts that the quality does not vary. 

Wilson. — The Wilson gas producer, like those already 
described, was not originally intended to generate gas for 
driving a motor, but if the furnace be £red with anthracite or 
coke, and the gases well washed, they can be used for that 
purpose. The method of introducing the steam is novel. It 
enters under pressure through a narrow tapering nozzle, and 
carries with it a strong current of air in the proportion of 
20 parts of air by weight to 1 of steam. In order that the 
whole of the air and steam may perfectly combine with the fuel, 
they are delivered into the centre of the glowing coal. Before 
they are carried off, the hot gases from the furnace are led into a 
chamber round the upper part of the producer, where the coal is 
fed in from a hopper. The fresh fuel is heated before combustion 
by these gases, and the chamber acts almost in the same way as 
a retort. The producer has also an automatic arrangement for 
carrying off the ashes and clinker. 

Many other systems for making gas have been patented, and 
some are now at work. Among these are generators by Grobe 
and Liirmann for steel furnaces, Sutherland for welding metals. 
Young and Beilby for extracting ammonia from gas. All, how- 
ever, are outside the present subject, as they have not hitherto 
been used to furnish gas for driving engines. Up to the present 
time only two apparatus have been designed and worked with 
the special object of generating gas continuously for motive power, 
the Dowson in England, and the Lencauchez in France. 

Lencauchez. — The Lencauchez system for making gas is of 
recent date, and the English patent (No. 4798) was taken out 
March 17, 1891. It was invented by M. Lencauchez, and the 
apparatus first made at the Chantiers de la Buire, Lyons, and 
called the Buire-Lencauchez system. In outward appearance 
the generator differs little from the Lowe, but the gas is continu- 
ously produced. It has now been adopted by MM. Delamare- 
Deboutteville and Malandin, the makers of the Simplex engine, 
and they have added a Buire-Lencauchez gas producer to many 
of their latest motors, from IG to 100 H.P. 

Fig. 95 shows a sectional elevation of the apparatus, attached 
to a Simplex gas engine. A is the furnace or generator with fire- 
brick lining K, between which and the outer iron casing is a 
layer of sand L. C is the grate, B the scrubber filled with coke, 
from whence the purified gases pass through Y to the gas holder. 
The fuel is automatically charged through a hopper, M N, above 
the furnace ; the ashes are withdrawn once in twenty-four hours 
through the door F. A current of air, previously heated by the 



198 



GAS ENGINES. 




'~lS)i K^t^nzi'ytr:. — : ' ■ ruii 



IPI 






V --a — -^ 



^ 



furnace, enters the generator at H from a fan or blower worked 
by the engine, and is driven into the closed pan G. By a 



GAS PRODUCTION FOB MOTIVE POWER. 199 

cock at W a small stream of water, preferably drawn from the 
jacket of the gas engine, is admitted into a hollow trough E, 
and falling through the bars DD on to the grate is there 
evaporated, and mixes with the blast of compressed air. The 
two pass together into the furnace, and the surplus water is 
carried off at J. The gases are then led off from the top of the 
furnace by the pipe S into the scrubber or jmrifier B filled 
with coke, upon which water from the siphon Z is continually 
playing through a perforated cone or distributor. W are 
the grate bars, X the door for withdrawing and changing the 
coke. On their way to the scrubber the gases pass the hydraulic 
joint T, which is intended to prevent the return of any gas 
to the furnace. The water dripping through the coke is carried 
off at U. The gases are next delivered sometimes to a distri- 
buting chamber, sometimes direct to the gas holder. If not 
required for driving the engine, they are allowed to escape into 
the atmosphere by a chimney. By an ingenious arrangement the 
furnace can be shut off for a few minutes, the injection of air 
and steam suspended, and the engine driven by gas from the 
holder while the grate is cleaned, an operation only necessary 
once in twenty-four hours. The holder contains sufficient gas 
for starting the engine. The production of gas is regulated by a 
valve I (through which the compressed air passes to the furnace), 
and which is attached by a chain to the top of the gas holder. 
As soon as the holder is filled, the valve T is automatically raised, 
and the air is not allowed to enter the furnace until the contents 
of the holder have been reduced. 

Advantages — Conanmption.— The Special advantages of the 
Buire-Lencauchez gas producer are its economy of heat and its 
simplicity, no boiler being required. Both the air and water are 
usually heated before they enter the furnace, and heat is thus 
utilised. This producer can also be used to generate gas from 
cheap and poor coal, whereas most others require anthracite or 
coke. M M. Delamare and Malandin no longer find it necessary 
to burn English anthracite in their Lencauchez generators, but 
inferior non-bituminous French coal, which is much cheaper. 
Hence the system is specially adapted for use where best coal 
is difficult to procure. French anthracite has neither the same 
calorific value, nor is it as pure as English. Gas made on the 
Lencauchez system with English anthracite has a heating value 
of 174 B.T.U. per cubic foot at ordinary temperature and pres- 
sure ; when cheap French anthracite coal is used, its heating 
value is 152 B.T.TJ. per cubic foot. With large motors driven 
by Lencauchez gas the consumption of fuel is about 1*3 lb. of 
good anthracite ])er H.P. per hour. A 60 H.P. Simplex engine 
has been working continuously with this gas since 1888 at 
M. Barataud's Mills at Marseilles. It is said to require a con- 
sumption of only 1 '2 lb. English anthracite per B.H.P. per hour. 



200 GAS ENGINES. 

In a paper published in the " Proc^ Verbaux de la Soci^t^ 
des Ing^nieurs Civils," October, 1891, details are given by 
M. Lencauchez of the economy which can be realised by using 
large gas engines driven by cheap gas, made in special generators. 
A good gas plant, burning the commonest fuel, transforms more 
than 80 per cent, of the solid combustible into gas, while the 
best steam boilers, according to M. Lencauchez, seldom utilise 
more than 70 to 75 per cent, of the heat contained in the coal. 
The thermal efficiency of the gas engine being usually reckoned 
at double that of the steam engine, a total economy of about 
50 per cent, of fuel may, the writer considers, be obtained by 
using poor gas instead of steam. 

DowBon. — It is to Mr. J. Emerson Dowson that the merit 
belongs of having fairly inaugurated the process by which steam 
and air are admitted to a furnace together. The gas obtained is 
much poorer than water gas, but richer than producer gas ; it 
can be rapidly and continuously generated, and with the proper 
admixture of air is very well adapted for driving gas engines ; 
it is not intended to be used for any other purpose. It 
possesses the further advantage of being much cheaper than 
lighting gas. Before its introduction, it was considered im- 
possible to work gas engines as economically as steam engines of 
about the same power. With few exceptions only small motors 
were made, and owing to the expense of town gas, it was 
supposed that large power gas engines could never compete 
successfully with steam. The adoption of Dowson gas has shown 
that it is possible to work a 100 H.P. engine with much greater 
economy than a good 100 H.P. steam engine, and a still more 
economical consumption of fuel has been obtained with an engine 
indicating 170 H.P. From this point of view, the services 
rendered by Mr. Dowson, in making it possible to produce power 
more cheaply by the use of his gas, are very great. It is now 
employed in a large number of motors, and although the cost of 
driving them has already been much reduced, the inventor is of 
opinion that " still better results can and will be obtained when 
an engine is really designed to give the best eifect with this 
gas." 

Fig. 96 shows an external view of a complete Dowson gas 
plant. To start production, nothing is required except anthracite 
or coke to fill the generator, and a little water to evaporate into 
steam for injection into the fuel. The steam pressure varies 
from 30 to 50 lbs. per square inch, according to the size of the 
gas plant to be served. The wrought-iron generator is seen in 
the front to the left of the drawing, and the small vertical boiler 
for producing the steam stands beside it to the right. The 
boiler has a closed grate, and a small serpentine coil of steam 
pipe above the fire. In this hot coil the steam is superheated, 
before it passes through the pipe above the boiler to the lower 



GAS PRODUCTION FOR MOTIVE POWER. 



201 



part of the generator. Midway between the two is an injector, 
through which a current of air is forced into the generator by 
the velocity of the steam. The cylindrical generator is lined 
with tire brick, and the fuel is fed in through the hop])er above. 
The gases generated by the combustion of the anthracite or coke 
combine with the oxygen derived from the decomposition of the 
steam and air, and are conveyed through a return valve and pipe 




Fig. 96.— Dowson Gas Plant. 

into the hydraulic box, shown at the extreme left of the drawing, 
under the floor. This box is divided into two parts and half 
filled with water. The gases passing through the water are 
washed, and another pipe conveys them to the scrubbers, usually 
placed inside the gas holder, to economise space. One is the wet 
scrubber, the coke in which is continually moistened by water 
sprays ; in the other dry coke is loosely stacked. From here the 



202 OAS ENGINES. 

partially purified gases enter the holder, and are thence conveyed 
to the engine, passing on their way through receivers containing 
sawdust, to cleanse them further. 

To regulate automatically the production of gas, the following 
method is adopted : — The top of the holder is connected to a 
chain attached to the air injector, and seen in the drawing. If 
too much gas is' generated, the holder rises, lifts this chain, and 
raises a valve from which the air and steam are allowed to 
escape, instead of entering the generator. As soon as production 
is reduced, the holder sinks, and the valve is released. At 
Fig. 97 is shown a Dowson gas plant at the flour mills of Messrs. 
Mead <fe Sons, Chelsea. The arrangement differs slightly from 
that already described, because the plant is larger, and the 
scrubbers are outside the gas holder, but the system is the same ; 
the different parts are indicated by letters. The trial made with 
this producer is mentioned at the end of the chapter, p. '205. 

A large number of ex])eriments have been undertaken with 
Dowson gas, and have proved its economy, and the relatively 
small cost of using it to drive engines. To make a proper com- 
parison between a steam-engine plant and a Dowson gas plant 
and motor, the cost of the fuel should in both cases be given, and 
the generator considered as forming part of the gas engine, in the 
same way as a boiler forms part of a steam plant. In England 
the gas can be produced at a cost of about 2d. to 3d. per 1,000 
cubic feet, according to the quantity required, but in the case of 
large works, where a steam boiler already exists, the consump- 
tion of fuel can be reduced, by utilising this steam for the 
generator. It should, however, be remembered that the gas 
contains about 55 per cent, of nitrogen and carbonic acid, as 
aojainst about 8 per cent, of nitrogen in gas manufactured by the 
Strong process, but besides being continuously generated, Dowson 
gas has a higher calorific value than producer gas. It is about 
four times less rich in heating value than town gas, and requires 
a corresponding diminution in the quantity of air used to dilute 
it in the cylinder of an engine. The actual charge admitted into 
a gas engine is no larger than with town gas, because this ratio 
of air is much smaller. Instead of from 5 to 14 parts of air to 
1 of gas, Dowson gas needs only from 1 to li, and 4 volumes of 
this gas are equal in heat to 1 of coal gas. The exact propor- 
tions of heating value of average coal gas as com[)ared with 
Dowson are 3 8 to 1. 

Difficulties were at first found on using it with the Otto engine, 
because the products of combustion were retained in the cylinder; 
but these have now been overcome. With the Simplex engine 
it gives excellent results, because the initial compression is 
greater, and the cylinder more completely cleansed before each 
explosion. Dowson gas can only be made with coke or anthracite, 
but both are easily obtained in England. It is yearly becoming 



GAS PRODUCTiaN FOR MOTIVE POWER. 



203 




mere widely known, and generally used. It is easily produced, 
the plant is compact and simple, takes up little space, and 



204 GAS ENGINES. 

requires little attention ; it does not bum with a smoky flame, 
and deposits no impurities in the ports and valves of an engine. 
It can be made continuously » rapidly, and at a mucli lower cost 
than town gas. 

Experiments. — Trials with Dowson gas will be found in the 
table at p. 404. Three types of engine have hitherto been tested 
with it, the Simplex, the Otto, and the Atkinson. The Simplex, 
engine was twice carefully experimented on by Professor Witz with 
Dowson gas. On the first occasion the engine indicated 8 - 1 H. P. , 
and the consumption of gas per B.H.P. per hour was 86*8 cubic 
feet. In 1890 M. Witz tested the 100 H.P. Simplex engine, 
shown at the Paris Exhibition, and found the consumption 1*34 
lb. English anthracite per Brake H.P. per hour. Experiments 
made by MM. Teichmann and Booking in 1887 on a 30 H.P. 
nominal Otto engine gave a consumption of 103 cubic feet of 
gas per I.H.P., equivalent to 1-67 lb. of fuel per B.H.P., per hour. 
With an engine indicating 18 H.P. at Messrs. Crossley's works, 
the normal consumption of Dowson gas during a working day is 
81*7 cubic feet per I.H.P. per hour, or about four times as much 
as lighting gas. Dowson gas is now used to drive all the engines 
at Messrs. Crossley's works, and it furnishes a total of from 
250 to 300 H.P. A good test of economy is found in the 
average working expenses throughout the year of large engines 
driven with this gas. At Messrs. Spicer & Co.'s Paper Mills 
at Godalining the total I.H.P. is 400. In all the engines 
Dowson gas is used, and the average consumption during 20 
weeks, including waste, was 1 lb. fuel per I.H.P. per hour. 
The same results per I.H.P. have been obtained at the Cro.ssley 
works during 35 weeks, with all their engines. In MM. 
Koerting's extensive engineering works near Hanover there 
are three engines, two of 25 H.P., and one of 16 H.P. driven by 
Dowson gas. At the Severn Tweed Co.'s Mills at Newtown 
two trials, each extending; over six days, were made upon four 
Crossley engines, driven with Dowson gas, and indicating a total 
of about !i80 H.P. In the first trial anthracite was used, and 
the total consumption was 1*23 lb. per B.H.P. j)er hour. During 
the second the generator was fired with coke, and 1*73 lb. per 
B.H.P. per hour was used. The average cost of fuel in each case 
was about the same per H.P. 

Two careful and important tests have recently been made, 
to test the economy obtained with Dowson gas. The first by 
Mr. J. Tomlinson was on a 15 nominal H.P. Atkinson Cycle 
engine, used to pump water from a well at the Uxbridge Water- 
works. The well was 100 feet deep, and the water had to be 
pumped into a reservoir a mile and a half away. The engine 
was coupled direct to double-acting pumps 80 feet below the 
surface, and was driven at 86 revolutions per minute. The total 
quantity of fuel used was 1*06 lb. per I.H.P. per hour, or 1*48 lb. 



THE THEORY OF THE GAS ENGINE. 205 

per water horse-power per hour, and about 164 per cent, of the 
\inits of heat in the fuel were .converted into total work, or 
12 per cent, into water power. The other trial was made in 
February, 1892, on a 16 H.P. nominal Crossley-Otto engine, 
using Dowson gas. The trial was conducted by Mr. Dowson 
himself, and gave results considerably more economical than any 
obtained with smaller engines. It is of special interest, because 
it was made on the largest engine yet driven with Dowson gas. 
The maximum I.H.P. was 173-6— B.H.P. 1476, but the engine 
did not run at full power, and the mean T.H.P. developed was 
118*7. The fuel consumed during the trial was 0*76 lb. per H.P. 
per hour, including the anthracite in the generator, and the coke 
in the boiler, but allowance was made for getting up steam. This 
trial was at Messrs. Mead & Co.'s Flour Mills, Chelsea. 

A large Dowson gas producing plant, capable of making gas 
for 200 indicated horse-power, has lately been erected at Messrs. 
Tangye's Works, Birmingham. The generator is fired with an- 
thracite or coke, and the gas is produced at a cost of 3d. per 
1000 cubic feet, equal to coal gas at, say, one shilling per 1000 
cubic feet. 

The following table (taken from A. Naumann's Paper on **The 
Transformation of Heat into Permanent Chemical Energy"*) 
gives the heat produced by the combustion of various gases :— 
Tabls op the Hbat of Combustion op Gases. 



Heating Gm. 


Heat of Combustion of 1 litre 

Gas, the Water produced 

beiug assumed to be gaseous 

latl5-C. 


Producer Gas, 

Carbonic Acid Producer Gas, . 
Water Producer Gas, from Uqnid water at 15^ 
Water Producer Gas, from gaseous water at 15°, 
Water Gas, 


1044 calories. 
1739 „ 
1652 „ 
1790 „ 
2812 „ 



[1 litre = 61*025 cubic inches = 0*0353 cubic foot] 



CHAPTER XVI. 
THE THEORY OF THE GAS ENGINE. 

Contents. — Laws of Gases — Boyle's Law — Gay-Lussac's Law — Joule's Law 
of the Mechanical Equivalent of Heat — Thermal Units ^Specific Heat 
— Camot's Law — Perfect Cycle — Isothermal and Adiabatic Curves — 
Ideal Efficiency — Other Cycles — Indicator Diagrams — Movements of 
Heat in a Cylinder. 

IjawB of Gkusies. — No complete study of the gas engine is pos- 
sible, unless it includes a knowledge, however slight, of the gas 
* BeriehU der deutschen chemi$chen OeselUcha/t, 25, 1892, pp. 556-62. 



206 GAS ENGINES. 

itself, or working fluid, the physical and chemical laws governing 
it, and the chief phenomena taking place in the cylinder of an 
engine. None of these phenomena are the result of chance. 
The laws controlling the action of gases have been accurately 
determined. The force of the explosion of gas in a cylinder 
seems, at first sight, impossible to regulate. But it can now be 
defined with precision, and is always exactly proportioned to 
the pressure and temperature of the gas when admitted, and the 
amount of its dilution with air. Thus, if a certain weight of 
gas, composed of known chemical elements in a definite com- 
bination, and diluted with a given proportion of air, be admitted 
into a cylinder of known dimensions, its action can be accurately 
foretold, and the work estimated which it is able to do. 

The term " working fluid " is applied to the medium of heat 
in thermal motors. It is equally correct to call it the " working 
agent," and the latter expression will here be used. No abso- 
lutely i)erfect gas is at present known, that is, a gas which obeys 
perfectly the theoretical laws, and cannot be condensed into a 
liquid by any change of temperature. But in the case of coal 
gas, air, or oil, the chief agents for the transmission of heat in 
internal combustion engines, the variation from a perfect gas is 
so slight that, for j)ractical pui-poses, it may be neglected. 

Of the different laws regulating the action of gases, two only 
are essential, in order to understand the phenomena in a heat 
engine. The first is known as Boyle's Law in England, and 
Mariotte's Law on the Continent. It was first propounded by 
Robert Boyle in 1662, and is as follows : — 

Boyle*B Law. — I. If the temperature of a gas be kept con- 
stant, its pressure or elastic force will vary inversely as the 
volume it occupies. 

This proposition defines the relation between the three attri- 
butes invariably found in all gases, whatever their composition 
— ^temperature, volume, and pressure. The word temperature 
denotes the condition of a body as regards sensible heat; volume 
is expressed in cubic feet, and the specific volume of a gas is 
the number of cubic feet it occupies per lb.; pressure is the 
elastic force the gas exerts upon the walls surrounding it, 
reckoned in lbs. per square inch. All the phenomena taking 
place in a heat engine are produced by varying one or other, or 
all three of these attributes, — that is, by increasing or diminish- 
ing the temperature, the volume, or the pressure of a gas. 
Boyle's law may be illustrated by imagining a cylinder containing 
a piston, both perfectly tight. The piston is set half-way through 
the length of the cylinder, and gas admitted on one side of it ; 
and the temperature of the gas being kept constant, the supply 
is next cut off. If the piston be then moved to its farthest 
limit, it will uncover the other half of the cylinder, and the 
available volume will be doubled. The gaa will instantly ex- 



THE THEORY OF THE GAS ENGINE. 207 

pand, following the piston, and as no more is admitted, the same 
quantity will occupy twice as much space as before. But this 
increase in volume of gas will also be accompanied by a corre- 
sponding diminution in pressure. The force exerted by the gas 
on the piston will, at the end of the stroke, be half as much as 
before. If the space originally occu{>ied by the gas be called 
one volume, and its pressure be taken as equal to that of the 
atmosphere, or in round numbers, a pressure of 15 lbs. on every 
square inch of the piston surface, the gas, when the piston has 
moved to the end of the cylinder, will occupy two volumes, but 
will exert a pressure of only 7^ lbs. per square inch upon the 
piston. The temperature being always the same, the products 
of the pressure and the volume will remain constant. To express 
Boyle*s law differently — 

Volume X pressure = constant. 

Now let us suppose that the temperature be at the same time 
varied; quite different conditions are immediately introduced, 
and the law no longer applies. If heat be furnished to the 
cylinder described, and the temperature of the gas raised, with- 
out allowing the piston to move out, the gas will continue to 
occupy the same space as before, but the increase of temperature 
will cause the pressure to increase. The heat will force the 
particles of gas further apart, and the pressure or tension will 
rise until, if the temperature be continually increased without 
an increase in the volume, the gas will burst the cylinder. 
This expansion of gas through the application of heat, and its 
corresponding contraction when heat is withdrawn, has been 
carefully verified, and the degree of variation in volume or 
pressure, determined by experiment, has been found to be in 
exact proportion to the quantity of heat added to, or abstracted 
from, the gas. It forms the basis of the following second law of 
gases, called Charles' law in England, and the law of Gay-Lussac 
on the Continent. 

G(ay-Lu88ac'8 XjEW. — II. The pressure or the volume of a 
gas being maintained constant, all gases expand ^4^ part of their 
volume, or increase in pressure Tj-fy part for every rise of 1° C. 
in their temperature. The law may be stated differently thus : — 

Suppose a gas is at constant volume in a closed vessel, and 
exerting a pressure of 273 lbs. per square inch. For each degree 
Centigrade added to its temperature, the pressure of the gas will 
increase 1 lb. per square inch. If, therefore, its temperature be 
raised 10* the pressure will be 283 lbs. per square inch. The 
converse of the law also holds good. All gases contract in volume, 
or lose YT^ part of their elastic force, for each degree Centigrade 
by which Uieir temperature is lowered. Therefore, if a gas at 
0* C. be reduced K, it will contract by ^}^ part of its volume, 
and if it were possible to continue the process, and to abstract 



208 OAS ENGINES. 

gradually 273° C. of heat from the gas, a point in temperature 
•would be reached, called the " absolute zero," at which the gas 
would possess neither volume nor pressure. This limit of the 
" absolute zero " is not a theoretical point, but definitely fixed 
by natural laws, and it is impossible to pass beyond it. Ac- 
cording to the law of Gay-Lussac, more heat could not be 
abstracted, even if the lowest limit of temperature were not 
reached, because the gas would have no further power of con- 
traction, and therefore of diminution in pressure. 

No one has yet been able to reduce a body to this extreme of 
cold, although in recent experiments it has been approached. 
The "absolute zero"— viz., 273' below 0" C. and 460° below 0" R— 
is, however, the basis of all calculations of temperature in scientific 
work. The zeros fixed by Fahrenheit, Reaumur, and Celsius are 
all arbitrary determinations, below which temperatures con- 
tinually fall, but they cannot be used as the original starting 
point for measuring heat.* In calculating the heat in an engine, 
the temperatures are usually measured from the absolute zei-o, 
or ordinary temperature Centigrade + 273°. Now in the 
first law of gases there are only two characteristics of a gas 
and their variations to be considered. In the second law, a 
third is added, and the relation between the three is expressed 
thus : — 

— ^— = Ratio or R. 

Put into words this formula runs : — The volume v multiplied 
by the pressure p of any gas, and divided by the absolute 
temperature T, are equal to a certain fixed ratio, R. The 
same law may, of course, be expressed thus : — 

V X p = R X T. 

The value of R for air is 29*64 units 0. 

This expansion of a gas y|^ of its volume for every degree 
Centigrade added to its temperature, is equal to the fraction 
-0036 7, called the coeflBicient of expansion. The term "coefficient" 
signifies a fixed quantity or mean value, accurately determined 
by experiment, and applying equally to all bodies possessing 
the same properties, and under the same conditions. If the 
amount of heat added to any gas be known, the degree to which 
it will expand can be exactly calculated by this coefficient. 
As it increases in pressure or expands in regular proportion 
to the heat added, it is evident that there must exist some 
fixed relation between the expansion of the gas, and the tem- 

* The centigrade scale fixed by Celsius has been practically adopted in 
Europe and America for scientific work. It is used in this book, in order 
ZLot to confuse the student passing on to other and more elaborate 
theoretical works, in which he will find no other temperature given. 



THE THEORY OF THE GAS ENGiyE. 209 

perature producing it. This relation forms a link between the 
laws of gases we have just been considering, and those governing 
the action of heat, and furnishes a good example of the first and 
most important Law of Thermodynamics, the Mechanical Equiv- 
alent of Heat. It may be briefly stated thus : — 

Joule's Law — Mechanical Equivalent. — I. Whenever heat 
is imparted to, or withdrawn from a body, energy is generated 
in proportion, or an equivalent amount of mechanical work is 
done by the body, or upon it by external agency. The propor- 
tion between the heat absorbed, or given out, and the work 
performed is always the same. 

This law, which has given a new direction to scientific thought 
during the last half century, was fore-shadowed by Count 
Kumford and Sir Humphrey Davy, and discovered almost 
simultaneously in England by Joule, in Germany by Mayer, 
and in France by Hirn. The priority is usually ascribed to 
Joule, who published the results of his accurate experiments 
in 1843, and the law is known in England as the Law of the 
Mechanical Equivalent of heat, or briefly as Joule's Equivalent. 
It is twofold in its operation and eflects, and may be expressed 
as : — Heat is a form of energy, or Mechanical energy (work) 
may be converted into heat according to a definite law. 

To explain it we will again use our illustration of a cylinder 
with an air-tight piston, containing a given volume of gas. 
As long as the temperature of the gas does not vary, its 
volume and pressure have been proved to stand to each other 
in exactly inverse ratios. As the one increases, the other 
decreases. If heat be added, the gas expands, the pressure 
rising in exact proportion to the increase in heat. It is the 
law of the mechanical equivalent which explains the reason of 
this increase in expansive power. Heat has been put into 
the gas, and disappears as heat, to reappear in some other 
form. Nor can it be otherwise. The Law of the mechanical 
equivalent is a necessary deduction from the principle that 
nothing in nature can be lost or wasted. All the heat imparted 
to the gas must be found again, either as heat, or transformed 
into some other form of energy. In the case of our cylinder 
and piston, all the heat will be changed into work, and will 
be absorbed in producing the expansive force of the gases 
driving out the piston. Were there no piston, and the cylinder 
open at one end, work, since it must be done by the expansion 
of the gases, would be done on the atmosphere. In no case can 
the heat imparted to the gas be lost. Either it is represented 
by the expansion of the gas, or carried off by radiation to the 
conducting substances surrounding the cylinder. 

The earliest and simplest example of heat transformed into 
mechanical energy is shown by a cannon, which is really a 
primitive form of heat engine. The bore of the cannon repre- 



210 . QA3 SKQIKES. 

gents a cjllnder, the bullet is acted upon in the same way 
as a piston. A solid combustible is used to produce inflam- 
mable gas, but the effect is the same as in a gas motor. Heat 
applied to this combustible or powder causes it to explode, and 
the force of the explosion, or expansion of the gases generated, 
drives out the bullet with great velocity. Not only can heat be 
thus transformed into actual work, but the converse proposition 
that energy may be translated into heat, has been demonstrated 
by many careful experiments. Both are mutually convertible 
forces, and this may be verified by suddenly arresting the pro- 
gress of the bullet. The energy of motion imparted to it by the 
heat of combustion and not yet expended, is immediately re- 
ti*ansformed into heat, and the bullet is found to be much hotter, 
than if it had been allowed to continue its course till its velo- 
city was spent. Sir Humphrey Davy demonstrated the truth of 
this proposition in another way, by his celebrated experiment 
of rubbing two pieces of ice together in a vacuum, without 
change of temperature. Water was produced, showing that 
the ice was partially melted, and the heat required to effect this 
change of state could only have been obtained by friction, — that 
is, by mechanical energy or work, as no heat had been added 
externally to the ice. 

The theory of the Mechanical Equivalent is equally applicable, 
whether a gas be heated or cooled. If heat be imparted to it, 
and the gas allowed to expand, the particles are driven further 
apart, if heat be abstracted they shrink. Work will be done 
on the gas by contraction, instead of by the gas through 
expansion. But if a gas be compressed at constant temperature, 
and no heat abstracted, work being done on it, and the gas 
caused to diminish in volume, heat will be stored up, and the 
temperature of the gas raised. The energy of motion or 
mechanical work of compression of the particles is transformed 
into heat. If, however, the heat is carried off in proportion as 
it is evolved by contraction, the gas will, as has been shown, 
gradually decrease in volume, in temperature, and in pressure, 
until the point of absolute zero is reached. In this way the law 
of the Mechanical Equivalent confirms the existence of an absolute 
zero. If it were possible for the gas to exceed this limit in any 
one of its three characteristics, the fundamental law of thermo- 
dynamics would be violated. If it could decrease still further 
in volume, work would be done in contraction without any 
correspondiDg diminution in temperature, and we should have 
energy without heat. The two aspects of the law in its 
application to gases are, expansion by the addition of heat, and 
contraction bv the withdrawal of heat. In a heat motor the first 
is called positive, and the second negative work. It is with the 
effect produced by external work, that the theory and practice of 
heat engines is chiefly concerned. 



THE THEORY OF THE GAS ENGINE. 211 

Thermal Units. — The proportion between the heat added 
and work done being a fixed quantity, it is possible to determine 
accurately the work theoretically performed for a given amount 
of heat supplied. The two are linked together in practice, and 
the relation in which they stand to each other is expressed in the 
following way : — In England it is usual to reckon that one unit 
of Heat or British Thermal Unit (B.T.U.) raises 1 lb. water 
1° Fahr., and if this unit of heat be applied to a body, it is 
equivalent to the work of lifting 772 lbs. 1 foot in height, or a 
weight of 1 lb. a distance of 772 feet. On the Continent the 
unit of lieat is called a ^* calorie,** One ccdoi-ie raises the tem- 
perature of 1 kilogramme of water V C, and if this quantity 
of heat be converted into work, it will lift 425 kilos, through 
1 metre, or 1 kilo, through 4'25 metres. The unit of measure- 
ment of work is called loot-pound in England (ft. x lb.), and a 
kilogram metre abroad (kilo, x metre). The difference lies only 
in the respective units of weight, and temperature employed 
here and on the Continent. 

The measurement of the exact proportions between heat and 
work was determined by James Prescott Joule, after long and 
careful experiments. The apparatus he principally made use of 
to verify the law of tlie mechanical equivalent consisted of a 
closed copper vessel fill«»d with water. Within it were revolving 
paddles attached to a vertical spindle. The spindle and paddles 
were made to rotate by means of a cord passing over a pulley 
connected to a weight. When the weight fell, the spindle 
rotated, causing the paddles to revolve and to agitate the water, 
and heat was produced by friction between them. The rise in 
degrees of temperature of the water was found to be exactly in 
proportion to the distance in feet passed through by the weight, 
multiplied by the number of lbs. it weighed. From these and 
many similar experiments with water and gases. Joule deduced 
his great law. 

Specific Heat. — All bodies have not the same capacity for 
absorbing heat. Those which are heated without changing their 
physical state require less heat to raise their temperature than 
bodies which are converted, during the rise, say from liquid to 
gaseous. A large quantity of heat must, for instance, be imparted 
to water, because, after it has absorbed a certain amount of heat 
it ceases to be a liquid, and becomes a gas, steam. Specific heat 
is the quantity of heat necessary to vary the temperature of any 
body through one degree, the quantity of heat required to raise 
or lower the temperature of an equal weight of water through 
one degree being taken as the unit. Water is universally 
adopted as the standard of comparison, and its specific heat 
being greater than that of most other bodies, their specific heats 
are expressed in fractions. For example, a heat unit represents 
the amount of heat required to raise 1 lb. of water 1° F., there*- 



212 GAS ENGINES. 

fore, 100 heat units will raise its temperature 100° F. The specific 
heat of mercury is •03332. To raise 1 lb. of mercury through 
100° F. will require -03332 x 100" x 1 lb. = 3-332 heat units. 
The specific heat of mercury is, therefore, about ^j^^ that of 
the same weight of water, which requires thirty times more heat 
units to bring it to the same temperature. Specific heat has been 
ably illustrated by Mr. H. Graham Harris under the similitude 
of "appetite."* 

Further, the specific heat of the same body will vary according 
to circumstances. If the body remains under stationary condi- 
tions, its specific heat will be less than if its condition changes. 
To return again to the cylinder containing a given volume of 
gas. As long as the gas remains inert or passive, and its volume 
does not vary, it possesses a definite specific heat, which being 
known, the quantity of heat to be added, to raise it to a certain 
temperature, can be calculated. But if the piston is driven 
out, by reason of tlie expansion of the pjas which, accord- 
ing to Gay-Lussac*s law, increases in volume by ^^^ for every 
degree rise in temperature, work will be done, and heat will in 
consequence be expended. More heat will, therefore, be required 
to heat the gas — ^that is, its "heat appetite" will be greater when 
it has forced out the piston than before. Under the first condi- 
tion, the heat absorbed by the gas is defined as its " specific heat 
at constant volume," because, the piston being stationary, neither 
the volume of the cylinder nor that of the gas has varied. As 
the piston moves towards the end of the stroke, the volume is 
increased, and expansion takes place. The heat of the gas is 
then called its " specific heat at constant pressure," because, 
while the volume of the cylinder has varied, the pressure over 
the piston area has been constant. Therefore the specific heat 
of the gas at constant pressure will be higher than at constant 
volume, and the proportion between the two represents the 
work done by the gas. That is to say, the increase of specific 
heat in the gas denotes the amount of heat required to maintain 
the requisite pressure on the piston, and, therefore, the work it 
has performed. 

. Tlie ratio between these two specific heats is of great import- 
ance, and has frequently to be employed in calculations of effici- 
ency or mechanical energy in a heat engine. It varies slightly 
as given by difierent authorities, but is usually reckoned at 1*39 
by foreign, and 1-408 by English writers. The following table, 
taken from Regnault, Grashof, Ayrton and Perry, and others, 
gives the specific heats of various gases at constant pressure and 
constant volume, and their ratio : — 

* See Mr. Harris's Cantor Lectures on *' Heat Engines other than 
Steam," delivered before the Society of Arts, May, 1889, to which the 
stiif^ent IB referred for an exceedingly clear elementary treatment of the 
subject. 



THE THEORY OF THE GAB ENGINE. 213 

Table of Specific Heats of Gases (from varioas Authorities). 



1 

1 S|H»ciflo Heat 


Spedflo Hd&t 








ut ConstADt 


at Constant 


Batlo. 






Volonio. 


Pre»Bare. 






Air at ordinary temperature, . 


0168 


0-237 


1-41 




Dry air (Rankine's constant), 




0-169 


0-238 


1-40 




Steam, 




• 0-369 


0-480 


1-30 




Hydrogen, 






2-406 


3-409 


1-41 




Nitrogen, . 






173 


0-243 


1-41 




Oxygen, . 






0155 


0-217 


1-40 




Carbonic oxide, 






0-173 


0-245 


1-41 




Carbonic acid, . 






0171 


0-216 


126 




Methane, . 






0-470 


0-o93 


126 










ijaa 





sources of waste must be guarded against. The temperature of 
the gas should, at the outset, be raised to its highest limit, as 
much heat as possible utilised in expansion, and as little as 
possible wasted. It is necessary to have at our disposal a source 
of heat and a source of cold, tlie one to impart, the other to with- 
draw the heat. These conditions bring us to the second law of 
thermodynamics, known as Carnot's, because it was first laid 
down by him in 1824. It is as follows : — 

Camot's Law. — II. If heat is exchanged at constant tem- 
perature between a source of heat and a source of cold, the 
proportion between the quantity of heat furnished and that 
abstracted depends only on the absolute temperatures (Centi- 



214 GAS BEranfES. 

grade + 273*), and not on the nature of the body to which the 
heat is imparted. The expression " constant temperature " 
means, not that the amount of heat present does not vary, but 
that it varies only in proportion to the work done, so that tho 
temperature is not affected. This law, when applied to the 
phenomena in a heat engine, results in what is called a *^ per- 
fect cycle." It supposes the whole difference of temperature 
between the "heat" source and the "cold" source to be utilised 
in doing work, and no heat to be carried off and wasted, a con- 
dition of things, of coiu*se, impossible in practice. 

But where, it will be asked, is the necessity for a source of 
cold ? Since the more heat is added to a gas, and absorbed in 
expansion, the more work will be done, why should not the 
whole of the imparted heat be thus utilised, and none remain to 
be withdrawn ? The reason is that, as there is an absolute zero 
to which no gas can ever be cooled, therefore the whole heat 
can never be converted into work. In a motor driven by water 
falling from a given height, to turn to practical account all the 
energy stored up in the water, it should fall to the centre of the 
earth ! As it can only descend a given distance, from whatever 
height it may come, only a certain proportion of its energy can 
be utilised. The same law applies to the fall in temperature of 
a heat engine. It is only within certain limits that this range 
of temperature can be varied, but the wider the limits, the 
greater the force or energy obtained. To enlarge these limits as 
much as possible, heat must be added, and the temperature of 
the working agent raised at the beginning. 

This fall in temperature of a gas, and the corresponding loss 
in pressure upon the piston, takes place inside the cylinder of a 
heat engine. To calculate the work done, it is very desirable to 
have a record of the actual pressures during the forward stroke. 
This is obtained by an instrument called an indicator, which is 
placed in direct communication with the cylinder, and gives a 
diagram marking on paper the varying pressures. The curve 
traced first rises abruptly, marking the sudden rise in pressure due 
to explosion at constant volume, and then falls gradually with 
increase of cylinder volume, showing how the pressures slowly 
decrease as the piston is driven out. To exhibit clearly the pro- 
portions between the loss of heat and pressure and the work done 
during the changes in the gas, two theoretical curves are used. 

I. The first is known as the Isothermal, and signifies from 
its name the curve of equal temperatures. Here the *piston of 
A cylinder moves out, by the expansion of the gas produced by 
the addition of heat, and the effect of the expansion is repre- 
sented by a curve in which the temperature is constant, and 
the pressure alone falls. It has been proved that, where work 
is done on the piston by a gas, the temperature must fall ; the 
isothermal curve, therefore, is based on the assumption that 



THE THEORY OF THE OAfl ENGINE. iSU 

iieat is added to the gas, to compensate for that lost in expaa- 
siozL This curve is never obtained in practice, but it is occa- 
sionally approached when the process of expansion in a heat 
engine is reversed, and heat is refunded to the gas by compres- 
sion. In either case, the volume of the gas varies in inverse 
ratio to the pressure. 

2. The Adiabatic is another theoretical curve, representing 
the fall in temperature when heat is neither added to nor ab^ 
stracted from the working agent, but expended only in doing 
work by expansion on the piston. The term is derived from a 
Greek word signifying " impenetrable,'' and was first applied by 
Rankine. The nearer the diagrams of pressure approximate to 
this cnrve, the more perfectly will the engine utilise the heat 
imparted to the gas. If the difierence in the specific heat of a 
gas at constant volume and at constant pressure be taken as 
representing the heat turned into work, the ratio between the 
two is graphically shown by the adiabatic curve. Since no 
beat is added or withdrawn, the temperatures of the adiabatic 
curve may be neglected, and the curve itself expressed only as 
▼olumes and pressures, thus p x v^^ or: — The pressures of the gas, 
multiplied by the volumes, raised to the power of the ratio of 
the two specific heats. 

Camot's Cycle. — Fig. 98 gives a graphic representation of 
Gamot's law which, plotted out in the shape of the curves just 
described, forms a perfect or closed 
cycle. Here the working agent, after 
passing through the phases of the 
addition of heat, expansion, abstrac- 
tion of heat and compression, is 
brought back theoretically to its 
original condition. The processes 
of heating and cooling can be con- 
tinuously repeated, or the sequence 

of operations reversed. The neces- t.. «« ^^ v r» "* 
.. K /. 1 J • -^ i. Fig. 98.— Graphic Represen- 

sity for a source of cold is manifest. ^^^^^^ ^f Camof s Law. 

If the working agent is a gas, it 

must be cooled to its initial temperature, and this cannot be 
accomplished by the work of expansion alone. It has hitherto 
been found impossible in any engine to aUowthe gases to expand 
to atmosphere, and thus use in work all the heat generated. The 
cycle (Fig. 98) is formed of two isothermal and two adiabatic 
curves,, and shows their theoretical forms on a small scale. The 
gas first receives heat from the source of heat, and expands along 
the line A B with increase of volume. As the temperature is 
not allowed to fall, the curve represents an isothermal. From 
B to there is another increase of volume. The gas expands 
without the addition of heat, the temperature fiiUs in conse- 
quence only of work done, and this line shows the carve of i *' 




216 OAS ENGINES. 

batic expansion. At C communication is opened with the source 
of cold, and heat is supposed to be withdrawn along the line 
D to the same extent as it was added from A to B. The 
volume is here diminished, and the line C D is again isothermal. 
From D to A the gas is compressed without heat being abstracted, 
and consequently increases in temperature, in proportion to the 
work done upon it. Compression is adiabatic, and at the end 
of the cycle the gas has returned to its original volume. 

Actual indicator diagrams of gas engines do not usually consist 
of four curves. There is first the line of addition of heat, nearly 
vertical, then the expansion line, conforming more or less to the 
adiabatic, and lastly the exhaust, or discharge of the remaining 
heat to the cold source, which is generally nearly horizontal. 
(See the diagrams of the various engines.) 

It is the peculiar merit of the Carnot cycle that heat is added 
when the gas is at its highest temperature, before any work has 
been done, and abstracted at its lowest, after expansion. Since 
the mechanical energy obtained is in strict proportion to the 
heat imparted to the working agent, this ideal or typical cycle 
furnishes and utilises the largest amount of heat. Hirn, the 
great French savanty says : — " It must be evident that this closed 
cycle has been designed to afford a maximum of work. The 
heat given up by the source of heat has been employed solely to 
produce work, and a maximum has therefore been obtained. The 
heat sent on to the refrigerator has been evolved as economically 
as possible, since the work has produced no variation of temper- 
ature. The object of the other two operations (along the curves 
C D and D A) has been solely to cause a fall and a corresponding 
rise in the temperatures and pressures." Thus the cycle obtained 
is perfect, since the heat supplied from the source of heat and 
by compression, is equal to the heat expended during expansion 
and conveyed to the refrigerator. Therefore the working agent 
or gas is at the close of the cycle in the same condition, that is, at 
the same temperature and pressure, as at the beginning. Clearly 
the source of heat and the refrigerator act by alternately expand- 
ing and contracting the working agent or gas. 

Carnot's Formula. — This cycle may be expressed by the 
following formula, in which Q represents the quantities of heat 
supplied by the source of heat, and q the quantities passed on 
to the source of cold, or in other words, rejected because they 
cannot be utilised. Tj is the absolute highest, and T^ the absolute 
lowest temperature, and E what is called the theoretical eflSci- 
ency of the engine : — 

V - Q - g _ T, - To _ , To 

^ - -Q- - "Tr - ^ - tt 

On this theoretical basis the heat efficiency is calculated between 
the highest and lowest temperatures. 



THE THEORY OF THE GAS ENGINE. 217 

Numerical Example. — In the Atkinson 9 H.P. engine, tested 
by the Committee of the Society of Arts in 1888, the temperature 
of the gases (Fahr.) on entering the cylinder was 676° absolute 
(Tg), and their temperature at the moment of highest explosion 
2990* absolute (Tj). The theoretical formula of efficiency is — 

_ T^-Tq _ 2990"^ - 576' _ 
^ - -T7~ - — 2990«~ - ^^ 

The student will here be inclined to ask what, in this simple 
formula, becomes of the ratios of specific heats at constant volume 
and pressure, the coefficient of expansion, and the other complex 
phenomena of expanding gases already descnbed. They are here 
expressed in their simplest forms, and nothing is taken into 
account except the quantities of heat, and the temperatures. 
Now the temperatures in a heat engine must, except the initial 
temperature of the gases, be deduced from the pressures and 
volumes. It is in making these calculations that the specific 
heat of the gases under different conditions, the ratio of expansion 
to increase of temperature, and other modifying circumstances 
have to be considered. To calculate the work of an actual engine 
four or five tempenvtures, with their corresponding variations of 
volumes and pressures, must be determined and calculated from 
experiment. The above formula gives the method of calculation, 
not the process by which it has been arrived at. 

Ideal EfGLolency. — Both the highest and lowest temperatures, 
Tj and Tq, in a heat engine, and the maximum amount of work 
which may be obtained from it, are restricted within certain 
limits. Even in this perfect cycle, it has been proved to be 
impossible for the lowest temperature, T^, to fall below a given 
point. The highest, Tj, is almost as rigidly defined by the 
phenomena of dissociation, the power of the cast-iron cylinder 
and the lubricant to resist great heat, and other circumstances. 
A perfect engine, therefore, is not one giving unlimited expansion, 
and 100 per cent, of work, but one which turns all the heat 
supplied to it between the limits 1\ and Tq into work. This is 
its maximum utilisation of heat, or what is called the '4deal 
efficiency " of the engine, which we will now compare with the 
practical efficiency, or the amount of heat a working engine can 
actually convert into motive power. 

To obtain the highest efficiency, an ideal engine must be sup- 
posed to work with — 1. A perfect gas, the volumes and pressures 
of which conform to the laws of Boyle and Gay-Lussac. A study 
of the chemical constituents of gases, and their action during 
combustion, shows that this conformity is never obtained in the 
cylinder of a gas engine. 2. No friction of the working parts. 
Friction generates heat, and heat we know is the equivalent 
of energy. Part, therefore, of the mechanical energy of the 
motor, which in an ideal engine cannot be taken into account, 



218 



GAS SNGIHSS. 



is absorbed to produce this heat. 3. No radiation or condaction 
of the heat through the walls of the cylinder containing the gas. 
Of course it is impossible to have a vessel theoretically of this 
nature, that is an absolute non-conductor of heat. As soon as 
the gas is at a higher temperature than the surrounding atmo- 
sphere, a cei*tain portion of the heat must be transmitted by 
radiation to the colder external air. 4. Lastly, expansion must 
be prolonged till the temperature and pressure of the gases is 
the same as at admission. This is also impossible. The tem- 
perature of the gases is always much higher than Tq, and there- 
fore much heat is discharged at exhaust. 

Other Cycles. — In the diagram shown at Fig. 98 the 
curves A B C D enclose an area representing not only the 
heat supplied, but the amount of work done by a heat engine. 
The curves, and therefore the shape of the area^ may, however, 
vary according to the way in which the heat is supplied to, and 
withdrawn from the engine, or according to the expansion and 
compression of the charge. Figs. 99 and 100 represent two other 





Fig. 99. — Constant Volume. 



Fig. 100.— Constant Pressure. 



theoretical cycles known, the first as Stirling's, the second as 
Ericsson's. Though the curves are here of different lengths they 
are, like those forming Camot's cycle, theoretically perfect, and 
form the boundaries of an equal area. Heat is added in both 
cycles from D to A, and abstracted from B to C, and these lines 
are designated by Professor Witz " isodiabatic," or lines of equal 
transmission of heat. The curves A B and C D are no longer 
adiabatic, but isothermal. The first represents the whole of 
the useful conversion of heat into work at constant temper- 
ature ; in the second the heat is refunded, and the same amount 
restored to the gas by compression as was expended in work. 
The lines B C and D A are straight, parallel in the one case to 
the vertical line, called an ordinate, at the left hand of Fig. 99, 
and in the other to the horizontal line (abscissa) at the bottom of 
Fig. 100. The areas enclosed within these curves form the bases 
of calculation of all diagrams i*epresenting work done in any 
heat engine. The ordinates in a diagram are in proportion to 



THE THEORY OF THE GAS ENGINE. 219 

the pressures in the cylinder, the abscissa to the length of 
stroke. 

The horizontal lines in these fignres represent the volumes of 
the cylinder. Along this line the piston may be said to travel, 
driven forward by the expanding force of the gas, and the farther 
it moves to the right the larger the cubic contents of the cylinder. 
If the piston is moved half way along the horizontal line, half the 
volume of the cylinder, reckoning from the dead point, will be 
uncovered by it. The horizontal line in an indicator diagram, 
therefore, represents volumes of the cylinder or lengths of 
stroke, and distances along it are calculated in feet or metres. 
The vertical line in the tigures, and in indicator diagrams of 
heat engines, represents the pressures of the gas obtained by the 
addition of heat, and is usually divided into sections reckoned 
as so many lbs. pressure per square inch of piston surface. So 
that we get horizontally feet^ and vertically ^6«., or ft. x lbs. = 
power proportioned to area of diagram. 

Indicator Diagrams. — It will make the study of the heat 
engine easier to the student if we describe here how an actual 
indicator diagram is taken, and the kind of instrument used to 
trace it The same type of apparatus is employed in gas as in 
steam engines. It consists of a small piston and cylinder in 
direct communication with the inside of the motor cylinder ; the 
piston is forced up or down with the varying internal pressures 
produced by the expansion of the gas. To the upper part of this 
piston is attached a small pencil. A drum covered with paper 
is made to travel to and fro at the same relative speed as the 
motor piston. The apparatus is so arranged that as the drum 
moves horizontally, tiie pencil of the indicator piston moves 
vertically. The pencil goes up and down in proportion to the 
cylinder pressures (lbs.) and the paper travels to and fro in pro- 
portion to the strokes (ft.) These two movements are brought 
in contact, and the pencil traces a diagram on the paper (see 
Fig. 102, p. 237). The vertical lines of this diagram represent 
lbs. pressure per square inch on the piston surface, and the hori- 
zontal lines feet travelled through by the piston. 

The pressures and the volumes of a gas being known from the 
indicator diagram, the temperatures are usually calculated from 
them. To determine these temperatures in a gas engine is, 
however, a difficult process, because many scientific men are of 
opinion that, at the moment of explosion, the gases in the 
cylinder are not at a uniform temperature throughout. • In the 
two closed cycles given in Figs. 99 and 100 the lines of addition 
and abstraction of heat, D A and B C, are in the first fij^ure 
parallel to the pressures, in the other to the volumes. This 
means that in Fig. 99 the heat is supposed to be added from 
the source of heat and withdrawn, while the volume remains 
constant, and the piston stationary at either end of the cylinder. 



220 GA8 ENGINES. 

In Fig. 100 the heat is added and abstracted while the pressure 
of the gas remains constant, the ]>iston being forced out, and the 
volume of the cylinder increased. More heat must be added 
for a given rise of temperature than in the other case, because 
a certain amount is expended in driving the piston. The two 
figures exhibit, under another form, the ratios of speciBc heat at 
constant volume and at constant pressure. 

It is from the indicator diagram, therefore, or diagram of pres- 
sures, that it is possible to know theoretically how much heat 
enters an engine (Q) and how much leaves it (q), and to determine 

Efficiency = E = ^-^ 

But this formula will not express the actual work done, or at 
least the determinations of Q and q will, under these conditions, 
be a matter of great diflSculty. Some of the various deficiencies 
in the cycle of a working engine have already been mentioned. 
There has hitherto always been a wide discrepancy between the 
theoretical possibilities of a heat motor, and the actual results 
obtained in practice. To discover the reason of this difference, 
complete investigations and experiments are very necessary. Not 
only do we need to know the total amount of heat supplied 
to an engine, and what becomes of it, but how and when the 
heat is added. Science has already done much to elucidate the 
first point ; our knowledge of the second is still' elementary. 

MoYements of Heat. — In Professor Scliottler's opinion it is 
requisite to study, not only the disposal, but the movement of 
heat in an engine. The initial temperature and the total amount 
of heat added having been ascertained, he proposes to represent 
graphically the different phenomena taking place in the cylinder, 
by substituting for the diagram of pressures what he calls a 
diagram of heat. The method originated with Professor Zeuner, 
who named it a graphic representation, or measurement of heat. 
In a diagram of tliis kind the volumes do not appear. The 
horizontal lines indicate the pressures, the vertical lines the 
temperatures in the cylinder of a heat engine. The area formed 
by them shows the work obtained, resulting from the tempera- 
tures and pressures in the cylinder, at different points of the 
stroke. The pressures being determined from the indicator 
diagram, the temperatures can be calculated from them, and the 
variations during the stroke obtained. The results arrived at, 
though somewhat complex, are more reliable than those given by 
other methods. 



THB CHKMICAI. COUFOSITION OF OAS IK GAS ENOINE8. 221 



CHAPTER XVII. 

THE CHEMICAL COMPOSITION OF GAS IN 
GAS ENGINES. 

Contents.— Atoms and Molecules — Chemical Symbols — Atomic Weights — 
Molecular Weights — Specific Heat— ChemiuiBj Equations — Heat of Com- 
bustion of Gas — Composition of Coal Gas — Calorific Value of Coal Gas, 
and of other Gases. 

In the preceding chapter we have seen that a gas engine is 
simply one form of heat engine, and that its object is to trans- 
fonn heat into work through the medium of gas — the working 
agent. We now want to know, further, how this process is 
carried on with maximum efficiency, so that the largest possible 
jiroportion of the whole heat we add to the agent may be con- 
verted into useful work. 

We must, therefore, examine more closely into the nature, 
composition, and specific properties of the gas employed 

The object of this chapter is to determine — 

1. What coal gas is ; 

2. How much air is required to burn it ; 

3. How much heat is given out during combustion, and 
carried away by the residual gases. 

As the nomenclature adopted by chemists renders the treat- 
ment of the problem of combustion of gases very simple, it will 
be convenient to begin with a brief explanation of its main 
principles. 

Atoms and Molecules. — All apparently homogeneous sub- 
stances are composed of extremely small particles, called mole- 
cules, which, for any given substance, have the same weight. 

These molecules, which are the smallest particles of the sub- 
stance which can exist in the free state, are, in general, composed 
of still smaller particles, called atoms. If all the atoms in the 
molecules are identical, the substance is known as an element, 
inasmuch as in this case, it is not possible to break it up into 
two or more distinct bodies. If, on the other hand, two or more 
different kinds of atoms exist in the molecule, it is known as a 
compound. 

The fundamental law upon whioh chemistry at the present 
day is based, first enunciated by Avogadro, is — " Equal volumes 
of gases (under the same conditions of temperature and pressure) 
contain equal num'bers of molecules." 



222 GAS EKUINEflL 

There is another way of stating this, which is sometimes use- 
ful. Take a cubic foot of any gas, say oxygen, at a fixed tem- 
perature and under a fixed pressure. It contains n molecules, 
where n is a very large number, only roughly known, and the 
exact value of which is not required here. The average space 

occupied by a molecule of oxygen then, is - cubic feet. This is 

called the " molecular volume " of oxygen. Now, since the same 
volume of any other gas, say hydrogen, by the law first enun- 
ciated, also contains ?/ molecules, its molecular volume is also - 

n 

cubic feet. Hence, another way of stating Avogadro's law is — 
" All gases have the same molecular volume." 
To resume then — 

1. All atoms of the same element have the same weight. 

2. All molecules of the same compound have the same weight 
and the same volume. 

Chemical Symbols. — As an abbreviation for one atom of an 
element, the first letter or first two letters of the word is used ; 
thus, C stands for an atom of carlx>n, H for an atom of hydrogen, 
O for an atom of oxygen, N for nitrogen, S for sulphur, and soon. 
Two letters placed together represent a molecule of a compound; 
thus, CO denotes one molecule of the compound carbonic oxide, 
formed by the combination of one atom of carbon C, and one 
atom of oxygen O. Similarly CO.^ denotes a molecule of the 
compound carbonic acid, containing three atoms, one of carbon 
and two of oxygen. -COo denotes two molecules of carbonic 
acid. 

Atomic Weights. — Now the actual weights of the atoms are 
excessively minute, and are only known very roughly indeed. 
But the reliitive magnitude of the weights of the atoms of the 
various elements can be, and has been determined with very 
considerable accuracy. It is customary to take the weight of 
the lightest known atom, hydrogen, as unity ; and the values 
for *• atomic weight" found in works on chemistry, represent 
the weights of the atoms of the various elements as multiples 
of this. 

All the gaseous elements dealt with here contain two atoms 
in each molecule. Thus Hg, Nj, Og are the molecular formula 
for tlie elementary gases — hydrogen, nitrogen, oxygen respec- 
tively. From this, and with Avogadro's law, it is easy to find 
the atomic weights of nitrogen and oxygen. It is found that 1 
cubic foot of hydrogen weighs '005591 lb. under standard con- 
ditions of pressure and temperature, 1 cubic foot of oxygen 
weighs -089456 lb., and of nitrogen, under the same conditions, 
■078:^8 lb. These numbers are in the ratio of 1 : 16 : 14. 
Hence, if wHg = 1 unit of weight, by Avogadro's law the same 



THB CHEMICAL OOHPOSITION OF GAS IN GAS ENGINES. 223 

number nOj^ 16 units of weight, and nNj = 14 units of weight — 
i.e., the atomic weights of hydrogen, oxygen, and nitrogen are 
as 1 : 16 : 14. The ouly atomic weights required in this 
chapter for gas engines are : — 



Table of Atomic Weights. 



Element 


Hydrogen. 


Oxygen. 


16 


Nitrogen. 

N 
14 


Carbon. 


Sulphur. 


Symbol, 

Weight of atom 
(in round numbers) 


H 

1 


c 

12 


S 
32 



Molecular Weights. — The "molecular weight" — i,e., the total 
weight of each molecule, when the hydrogen atom is the unit of 
weight, is obtained by simply adding together the weights of its 
constituent atoms. Thus the molecular weight of hydrogen, Hg, 
is 2 ; of oxygen, Oo, is 32 ; of carbonic oxide, CO, 12 + IG = 28 ; 
of marsh gas, CH^, 12 + (1 x 4) = 16. Hence the weight of 
1 cubic foot of hydrogen being -00559 lb., that of a cubic foot 

of carbonic oxide is ( — ^ — ~\ = 14 x -00559; of marsh gas, 

4 + 12 

5 = 8 X -005 5 9 ; and so on for any other gas. 

Specific Heat. — If a quantity of heat is added to a gas it 
may result in an increa.se of pressure, temperature, or volume, 
or in an increase of all three. Thus, there may be several 
" specific heats.*' The only two generally used are : — 

(1) The specific heat at constant volume, which is defined as 
the number of units of heat required to raise the temperature 
of the unit weight of gas through V, the volume of the gas 
remaining constant ; and 

(2) The specific heat at constant pressure, where the gas is 
allowed to do work by expanding. 

Of these the former, which is obviously the smaller number, 
is sometimes termed the " true specific heat," all the heat going 
in this case to increase the internal energy of the gas. 

For the elementary gases, hydrogen, oxygen, and nitrogen, 
and also for carbonic oxide, it is found that the amount of heat 
required to raise equal volumes through 1° is very nearly the 
fiame; or, in other words, that the specific heat x molecular 
weight ^ constant. It is also found that the specific heats are 
nearly independent of the temperature, tending only to increase 
very slightly with it. For the more complicated molecules, 
such as marsh gas, CH'^, ethylene, CgH^, &c., which occur in 



224 OAS ENGINES. 

coal gas, neither of these relations hold, the amount of heat 
required to raise, say 1 cubic foot of ethylene through I'F., is 
sensibly different from that required to raise the same volume 
of air throujjjh TF., and, further, the specific heat increases very 
rapidly with the temperature. 

The table of speciBc heats will be found on p. 213. 

Chemical Equations. — Chemical equations are symbolic re- 
presentations of chemical changes. It ivill be convenient to take 
one equation as a type and explain it in detail. The following 
is a useful example : — 



CH4 + 


20, 


CO, + 2H80 


(12 + 4) + 


2 (32) 


= (12 + 32) + 2 (2 + 16) 


Methane. 


Ox3-geD. 


Carbonic AolJ. Steam. 



This is interpreted as follows : — Since 1 molecule of methane 
combines with 2 molecules of oxygen, it follows, by Avogadro's 
law, that 1 volume of methane combines with 2 volumes of 
oxygen, giving 1 volume of carbonic acid and 2 volumes of 
steam. This same equation also expresses the fact that 16 lbs. 
of methane require 64 lbs. of oxygen for complete combustion, 
and give as the resulting products 44 lbs. of carbonic acid 
and 3G lbs. of steam. By the term ** complete combustion" is 
meant that tlie hydrocarbon comV)ines with the maximum pos- 
sible amount of oxygen, giving carbonic acid and water only as 
the final products. 

When the quantity of oxygen required for the combustion of 
each constituent is known, the next step is to determine the heat 
evolved by combustion. As this heat cannot be measured in 
the cylinder of an engine, the caloriraetric value of the gas is 
obtained by burning it in oxygen. For this purpose an in- 
strument is employed, called a calorimeter. MM. Favre and 
Silbermann were the first to design an apparatus for testing the 
heating values of solid, liquid, and gaseous fuels, and other 
calorimeters have since been brought out. 

Heat of Combustion of Gas. — The amounts of heat de- 
veloped by the complete combustion of the various carbon 
compounds contained in coal gas, have been experimentally 
determined in two ways. Fir-stly, by burning a current of the 
gas in question in oxygen or air at the ordinary atmospheric 
pressure, and, secondly, by exploding a mixture of the two gases 
in a strong steel ** bomb.'' 

The advantages of the second method, which was first used 
by Andrews, and has been recently employed in an improved 
form by M. Berthelot and M. Mahler, are that the combustion 
takes place at constant volume, and that on account of the 
much shoi-ter time occupied by the reaction, the " corrections 
for cooling " of the calorimeter are very much reduced 



THE CHEMICAL COMPOSITION OF GAS IN GAS ENGINES. 225 

One gramme of the fuel, the heating value of which is to 
be determined, is introduced into the closed vessel or bomb, 
placed within an outer shell filh^d with water. Pure oxygen 
is then admitted to the inner vessel at a pressure of 25 
atmospheres, the mixture is instantaneously tired by the 
electric spark, and the rise in temperature of the surrounding 
water shows the heat evolved during combustion. Extremely 
delicate thermometers are used, marking the rise in temperature 
to within y^ of a degree. M. Berthelot lined his inner vessel 
or calorimettic bomb with platinum, to resist the sudden and 
intense heat. This metal is very costly, and a less expensive 
calorimeter has lately been introduced by M. Mahler, in which 
the *'bomb" is of steel lined with enamel, but it is similar to 
Berth elot's design in other respects. 

With the help of this apparatus, the heat of combustion of coal 
and other fuels, solid and liquid, and of most kinds of combus- 
tibles, has been determined. The following table gives the values 
by the different authorities of the heat produced by the com- 
bustion of the chemical constituents of coal gas, and also of solid 
carbon : — 



Heat pboducsd by the Combustion of H, C, CO, &c (from 0stwald*8 
VerwandUcKaJU-Lehre, 1887). 



Unit Weight or Gramme of 


Unita of Heat eTolred by Complete Combnetloa of 
1 gramme at li* C, and Atm. Presaura 


FaTreand 
S-lbermaon. 


Thomeen. 


Berthelot 


Thomaen. 


Hydrogdn, M, . 
Carbon, C, . . . 
Carbonic oxide, CO, . 
Marsh Gas. OH4 . 
Ethylene, C2H4, 
Benzene, CeH^, 


CaL 

34,460 

8,080 

2,403 

13,062 

11,867 

9,016 


Cal. 
34,180 
8,080 
2,429 
13,244 
11,907 
10,249 


Cal. 

34,600 

8,138 

2,4,39 

13,344 

12,193 

9,949 


B.T.U. 
61,660 
14,640 
4,372 
23,860 
21,430 
18,448 



That is to say, 1 gramme of carbon completely burnt gives out 
sufficient heat to raise the temperature of 8,080 grammes of 
water 1' C. or 1 gramme water 8,080' C. according to Favre 
and Silbermann's reckoning. MM. Berthelot and Mahler claim 
to have obtained more accurate results with their new calori- 
meters, owing to the more rapid and complete method of 
combustion ; their values are slightly higher. 

The following table shows the number of British thermal 
units given out by the complete combustion of 1 cubic foot of 
each of the gases usually present in coal gas : — 

15 



226 



GAS ENOIKB8. 



Table ov B.T.n. rbsultino vbom the Complete Combustion of 

1 CUBIC rOOT OF DiFFEBBKT OaSES. 



Name of Gm. 






Oilortflc y»luM, ftt Ordinary 

Tempemtnrtf and PrvMare, per Coblo 

Foot (meAnared at zr F. and 30 liu. 

pre^eare of Meroary) in B.T.U. 

(BriUbh Thernui Unitt.) 


Hydrogen, . 
Carbonic oxide. 
Methane, . 
Ethylene, . 
Propylene, . 
Butylene, . 
Benzene, 










293-5 
342-3 

1,066 

1,678 

2,479 

3.275 

4,023 



The unit of heat used here is the amount of heat required to 
raise 1 lb. of water, at 64' to 68' F., V F. The difference 
between the specific heats of water at 0* C. and water at 19* is 
only about 1 in 1,000. The products are supposed to be cooled 
down to about 19° C. As the figure given for hydrogen includes 
the latent heat of steam, it may be replaced by the figure 52,500,* 
in which this latent heat remains in the steam gas. 

Composition of Coal Gtos. — ^As regards the actual com- 
position of coal gas, the following table, taken from Schottler, 
shows an average composition of 1 cubic foot of ordinary 
Hanover lighting gas, distilled from coal in retorts, without 
admixture of air : — 

Table showing Average Composition of 1 cubic foot of Hanotbr 
Coal Gas (SchOUlfr\. 



Volmne. 


Name of Gaa. 


Chemloal SymboL 


Cubic Feet 






-0069 


Benzene. 


C«H« 


•0037 


Butylene. 


C4H. 


•0211 


Ethylene. 
Methane. 


C,H4 


•3765 


CH4 


•4627 


Hydro^. 


Ht 


•1119 


Carbonic oxide. 


00 


•0081 


Carbonic acid. 


CO, 


•0101 


Nitrogen. 


Nt 


1-0000 



The first three gases are called ** heavy hydrocarbons," and as 
they are all frequently absorbed together by the same reagent 
(fuming sulphuric acid), they are generally included together 
under one head. 



♦52,500 B.T.U. in 1 lb. H., 
H. per lb.) = 293-5. 



52,500 X 000559 (weight 1 cubic foot 



THB CHEMICAL COMPOSITION OF GAS IN GAS ENGINES. 227 

Btmene^ OaHa, burns with exoMs of oxygen m follows : — 

Molecular weight, 78; weight of 1 cable foot = 30 x -005591 = '2181 

♦C«H« + 710, = 6C0, + 3H,0 
(IvoL) + (7ivoU.) a (6 vols.) + (3 vols.) 

BtUylene, C4Ha (Synonym— Tetrylene). 

C4H« + CO, = 4C0, + 4H,0 

(1vol.) + (6 vols.) = (4 vols.) + (4 vols.) 

Molecular weighty 56 ; weight of a cubic foot, 28 x *005591 ^ '1506 
lb. 

IMytoie, C,H4 (Synonyms— Olefiant gas, ethene). 

0,H4 + 30, = 2C0, + 2H,0 
(IvoL) + (3 vols.) ^ (2 vols.) + (2 vols.) 

Molecular weight, 28 ; weight of a cubic foot, 14 x *005591 = *0783 
lb. 

Meihanef CH4 (Synonyms — Marsh gas, firedamp). 

CH4 + 20, = CO, + 2H,0 



CH4 + 20, = CO, + 2H,0 

(IvoL) + (2voU.) = (IvoL) + (2 vols.) 

ir 
Hydrogen, H,. 



Molecular weight, 16 ; weight of a cubic foot, 8 x *005591 = -04472 
lb. 



♦H, + 40, = H,0 
(IvoL) + (IvoL) - (IvoL) 

Molecular weight, 2 ; weight of a cubic foot, -005591 lb. 

Carbonic Oxide, CO (Synonym— Carbon monoxide). 

♦CO + 40, = CO, 
(1 voL) + H voL) = (1 voL) 

Molecular weight, 28 ; weight of a cubic foot, 14 x '005591 = *0783 

Carbonic Add, GO, (Synonyms — Carbonic anhydride, carbon dioxide).^ 

Molecular weight, 44 ; weight of a cubic foot, 22 x -006501 = *123 
lb. 

Ifitrogen, N,, does not play any active part in the combustion, but 
remains unchanged throughout the whole sefc of operations. It acts as 
a mere diluent. 

Molecular weight, 28 ; weight of a cubic foot, 14 x -005691 = *0783 
lb. 

Since the whole of the oxygen represented in the above eqaa> 
tions has to oome from the air, and since there are in the air 79 
▼olnmes of nitrogen to 21 of oxygen, it follows that one Tolonie 
of oxygen must be replaced by about 4*762 of air. 

* To be strictly accurate, these equations should be doubled, but the 
volume relations are more clearly shown as they are. Of coniie, half a 
molecule is a physical impossibility. 



228 



GAS BNOIKES. 



The preceding data may be oonvenientlj tabulated as 
follows : — 



Table SHOwiKO PaoDUcrs of CoHBasnoN of the Various 
Constituents of Coal Gas. 



Name. 


FormaU. 


DeDtftylnlbB. 

per cub. ft. at (/• 

C. ftnd 760 mm. 

pressure. 


Volameii Oxy- 
gen requiPAd 
for Complete 
CombuBiioD. 


Volaraes 
of Air. 


Volames 

CO, 
Produced. 


Benzene, . . . 
Butylene, . - . 
Ethylene, . . . 
Methane, . . . 
Hydrogen, . . . 
Carbonic oxide, . 
Carbonic acid, . 
Nitrogen, . . . 


CO, 


•2181 

•1566 

•0783 

•0447 

•00569 

•0783 

•r230 

•0783 


5* 

3 
2 

4 
4 


35-71 

28-57 

14-28 

9-52 

2-38 

2-38 


6 

4 
2 
1 


1 



The com position of lighting gas is not constant. It depends 
upon the quality of the coal, the temperature of the retort, and 
the period of distillation. The following table, from experiments 
by Dr. Wright,* shows the influence of the time that has elapsed 
afber charging the retorts. 



Coal Gas. 









Constitaenta. 














10 minutes. 


8 boors 2fi min. 


6 bonra 85 mia. 


Hydrogen, . , 


H, 


•2010 per ct. 


•5268 per ct. 


•6712 per ct. 


Marsh gas, . . 


CH4 


•6738 „ 


•3354 „ 


•2258 „ 


Carbonic oxide, . 


CO 


•0619 „ 


•0621 „ 


•0612 „ 


Heavy hydrocar- 










bons, . . . 


... 


•1062 „ 


•0304 „ 


•0179 „ 


Nitrogen, . . . 


N, 


•0220 „ 


•0-255 „ 


•0(178 „ 


Carbonic acid, . 


CO, 


•0221 „ 


•0149 „ 


•0150 „ 


Sulphuretted hy- 










drogen, . . . 
Cub. ft 


8ti, 


•0130 „ 


•0049 „ 


•0011 „ 


10000 „ 


1^0000 „ 


10000 „ 



The following table shows the composition of the coal gas in 
most of the large towns of Europe, &c. : — 

*Joum. Chem, Soc,, No. 261, 1884. 



THE CHEMICAL COMPOSITION OF GAS IN GAS ENGINES. 229 



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230 



QAS ENQIKEB. 



Caloriflo Value of 1 Cubic Foot of any Coal Qbs. — From 
the table of B.T.U., p. 226, it is now easy to find the calorific 
value of 1 cubic foot of auj lighting gas, it being only necessary 
to multiply the volume percentage of each combustible gas by 
its calorific power per cubic foot, as given in the second column 
of that table. 

Take for example the following gas : — 



Name of Gas. 


Volames in 
enb. ft. 


Caloriflo 

Value ar.u. 

in 1 cub. f L 


Weight in lbs. 
per oab. ft 


Volaniea 
reqoired. 


Metbaoe, . 
Ethylene, . 
Butvlene, 
Hydro^ea, . 
Carbonic oxide, . 
Nitrogen, CO, and 0» . 


•4280 
•0277 
•0278 
•4360 
•0430 
•0376 


4562 
465 
910 

128-0 
14-7 


-019130 
•00-2169 
•004353 
•002437 
•0(i:<366 
-003220 


•8560 
•0631 
•1668 
•2180 
•0215 




10000 


736-4 


•034680 


1-3454 



i,e., 1 cubic foot of this gas on complete combustion would yield 

736-4 B.T.U., or ^^^ = 21,230 B.T.U. per lb. of gas, and 

wonld require 1-345 volumes of oxygen or 6*407 of air for 
complete combustion. 

As a matter of fact, when 1 cubic foot of this gas is mixed with 
1-345 volumes of oxygen, the explosion is so violent as to be 
quite unmanageable. Even when diluted with nitrogen as in air, 
the correct proportions for complete combustion (here 6*407 
volumes of air to 1 of coal gas) still give too violent an 
explosion. This can be moderated by usiug an excess of air 
which acts as a diluent, lowering the partial pressure of the 
re-acting gases. This excess of air, together with the whole 
of the 5*062 volumes of nitrogen introduced with the re-acting 
oxygen, and the nitrogen originally present in the gas, un- 
avoidably impairs the efficiency, as the whole of this has to be 
heated up to the temperature of the cylinder gases. Further, it 
is discharged at a high temperature (about 400* to 450* C.) 
together with the carbonic acid produced in the reaction, and 
the whole of this heat is wasted. In the various producer and 
water gases, formed by forcing air or mixtures of air and steam 
over red-hot coal, the amount of nitrogen is considerable, and 
accordingly much less air is required for their complete combus- 
tion. Thus, wherever coal gas requires from C to 15 volumes of 
air, Dowson gas requires only 1^ volumes. 

The following table gives the composition of several of these 
cheaper gases : — 



THE UTILISATION OF HEAT IK A OA8 ENOINB. 



231 



Table of Compoaition of Poor Gases. 



Name of (H». 



Prodnoer gas (Siemens'), 
Water gM, . 
Strong gas, . 
Lowe gas, . 
Dowsongas, 

>» 
Lencanchex^ 



010 



003 
0*23 
0-60 



8-6 
60-50 
63-0 
30-0 
18-73 
24-36 
20-00 



it 



2-4 
0-60 



0-31 
116 



II 



31 
015 
4-0 



24-4 

44-40 

35 

28 

25-07 

17-56 

21-00 



5-2 
1-60 
40 
340 
6-67 
607 
500 



59-4 

8^ 

8-0 

48-08 

50-48 

40-50 



It may be useful, as an example, to work out the calorific 
value of one of these, saj Siemens' producer gas : — 

Heating Value of 1 Cubic Foot of Siemens' PBODtrcKB Gas in 
British Thermal Unfts. 



(Hm, 



Hydrogen, . 
Methane, . . 
Carbonic oxide, 
Carbonic acid. 
Nitrogen, . . 



SyuboL 



H, 
CH4 

CO 
CO, 

N, 



AiDoant 
inlcaUfL 



•086 
-024 
-244 
-052 
•594 



CaloriOo 

Value 

per oabb ft 



293-6 
1066-0 
3423-0 



1-000 



Cftlorlflc 

Value 
per cab. ft. 

of Q«B Id 
B.T.U. 



25-24 
26-58 
83-51 



135*33 



Volamee 
ofUzyKen 
required 
in cub. ft 



•043 
-048 
•122 



0-213 



Volotnes 
of Air re- 
quired in 
enbb ft. 



•205 
•229 
-581 



1-015 



Hence the calorific power of this producer gas is, roughly 
speaking, only one-fifth that of an equal volume of coal gas, 
and it requires only a little more than its own volume of air for 
complete combustion. 



CHAPTER XVIIT. 
THE UTILISATION OF HEAT IN A GAS ENGINE. 

Contents. — Gas Power vernwi Steam — Balance of Heat — Foar Efficienciea 
— Ideal Diagram — Actual Otto Dingram — FormulsB of Efficiency — 
Four Types of Engine— Heat Balance Sheet. 

Having now considered the laws governing heat, the chemical 
nature of the changes taking place in the charge of gas and air 
in an engine cylinder, and the heat developed, we come to the 



232 OAS ENGINES. 

question how far this heat is really usefully employed as motive 
power. Upon this vital point the whole theory and practice of 
a heat engine rest. The heat supplied is used to drive out 
a piston, but it can never all be turned into work. The 
analyses and calculations of the heat of gases in the preceding 
chapter enable us to determine how much heat goes into a 
motor cylinder, and we must now try and trace what becomes 
of it. What is the proportion wasted and utilised 1 What are 
the causes of the waste of heat, and consequently of power, and 
how far can this loss be avoided, in the construction and working 
of a heat engine 1 

An erroneous idea is sometimes prevalent that heat is a mys- 
terious attribute imparted to a body, which cannot be measured 
or accounted for. The heat evolved in a gas by combustion in 
a cylinder does not disappear in some unknown manner. Either 
it remains to raise the temperature of the gas, or it is dissipated 
in one of three different ways. A certain quantity is radiated 
into the atmos[)here through the walla of the cylinder, and into 
the water jacket. Some is expended in power, according to the 
law of the mechanical equivalent ; and a proportion, varying 
according to the more or less perfect cycle of the engine, is left 
at the close of expansion, to be carried off into the atmosphere 
at the exhaust stroke. 

G-as Power as Compared with Steam. — Both in theory 
and in practice the gas engine even now, although it is only of 
late years that it has been carefully studied, turns more heat 
into work than a steam engine. This is chiefly because the 
range of working temperatures is very much higher. In a boiler 
and steam engine the source of heat, the furnace, is separated 
from the engine, and the steam is raised to its highest temper- 
ature before it enters the cylinder. However carefully the steam 
pipes may be covered, they carry off some heat. The temperature 
of the working agent cannot be so great when heat is added 
externally, before work on the piston is begun, as when it is 
imparted actually inside the cylinder, as in a gas motor. When 
the water in a boiler is converted into steam, a change of physical 
condition takes place. A certain quantity of heat becomes latent, 
or is stored up without raising the temperature of the steam, in 
order to produce the change from a liquid to a gaseous state. 
Nor does steam wholly conform to the law of Gay-Lussac, be- 
cause it is not a perfect gas. It increases more rapidly in pres- 
sure than in temperature, when heat is applied to it. At a 
temperature of 450° C absolute, it has a pressure of 10 atmo- 
spheres = 150 lbs. to the square inch. From these causes the 
initial temperature of the steam is relatively low ; the range, or 
difference between the two sources, is never very great, and 
consequently less heat is available to be utilised in work. The 
efficiency of a well-jacketed modern steam engine may be taken 



THE UTILISATION OF HEAT IK A OAS ENGINE. 233 

at from 8 to 14 per cent, depending on the speed, pressure, &c. 
— that is, about one-seventh or one-twelfth of the heat received 
by the engine is turned into work (exclusive of boiler). 

In gas enjjines the conditions are very different. Combustion 
generally takes place in the cylinder itself, or in a contiguous 
chamber, and there is no boiler or its equivalent. The gas is 
introduced into the cylinder at a comparatively low temperature. 
The heat is produced at once by explosion and combustion, 
and utilised on the piston. The theoretical temperature 
of explosion obtained by calculating the heat of combustion 
of the chemical constitueuts of the gas, is estimated at from 
2,C00* to nearly 4,000* 0. As there is no change of physical 
state in the gas, no absorption of latent heat takes place. To 
these two causes, viz., internal combustion, and permanence of 
physical state in the gas, the greater practical e£Bciency of a gas 
engine is chiefly due. As compared with steam, it turns into 
work about twice as much, or from 15 to 22 per cent, of the total 
heat supplied to it, according to speed, size of engine, <&c. From 
these figures, however, it must not always be assumed that, in 
all cases, the ])ower at the end of the crank shaft is obtained more 
economically, because the mechanical efficiency of the gas engine, 
or the ratio of brake to indicated horse-power, is generally 
lower than that of a steam engine. In other words, a gas 
engine often takes more power to drive itself than a steam 
engina 

But there are limits to the heat obtained by internal com- 
bustion in a gas engine cylinder. Far more heat is developed 
than can be utilised, or brought safely into contact with the 
working parts of the engine. Professor Witz says that the 
limit of working temperature in a heat engine throughout the 
stroke, is estimated at about 573** absolute = 300* C. It is 
true that much higher temperatures are obtained in a gas 
engine ; they cannot indeed be avoided, but neither can they 
at present be properly utilised. A temperature of 1,600* C. or 
1,873 absolute is taken by the best authorities (for it is 
impossible to determine it directly) as an average maximum 
temperature of explosion, and it is seldom lower than 1,000 C. 
or 1,273* absolute. Such heat must be instantly counteracted 
and dispersed, and this is obtained by circulating water in the 
jacket round the cylinder, and thus lowering the temperature 
of the gas at explosion and afterwards. If it were not for these 
practical difficulties, the 20 per cent, actual efficiency mentioned 



above would be considerably increased. In the formula 



T,-To 



p. 216, T^ is the maximum temperature of explosion. Practically 
about one-third to one-half this heat T^ is carried off by the action 
of the walls and water jacket, and mucli of the remainder escapes 
with the unburnt gases. The colder walls abstract heat which 



234 



GAS ENGINES. 



must be dispersed, bnt might with great advantage be retained. 
Their action is necessary, bnt not perhaps to its full extent, and 
here is a great opening for future improvement 

Balance of Heat. — A most useful method of studying heat 
and its utilisation in any engine was first introduced by the late 
G. A. Him. He drew up what he termed a heat balance sheet, 
showing on one side all the heat given to an engine, and on the 
other how it was expended. It is now usual, following his 
method, to make such a heat balance, in calculating the results 
of an engine. The heat received is put on one side of the 
account, and that dissipated, measured, and unaccounted for 
on the other. In a gas engine such a heat account, as shown 
by actual experiments, is about as follows : — 



Gas Ekgiks— Heat Baiance Account. 



Dr. flMt received by the Engine. 




Heat units (T.U.) re- 
ceived per explosion. 

Total, 


Percent. 
100 


Jnwork(T.U.). . 

Carried off by jacket, . 

Carried off in exhaust 
gases, .... 

Carried off by condaction 
and radiation and un- 
accounted for, . 

Total, 


Percent 
22-32 
32 96 

43-29 
1-43 


100 


100 



Of course, the figures vary much with different engines, but 
the above may be taken to represent good working c mditions. 
They are drawn from Professor Capper's trial of a 7 nominal 
H.P. Crossley engine, Appendix, p. 355. (See other Heat Balance 
Accounts on p. 242.) 

The actual heat supplied to an engine cannot be calculated, 
unless the calorific value of the gas is known, and the most 
accurate method of determination is by chemical analysis. The 
ga.s varies sometimes from hour to hour in the ])roportions of 
its chemical constituents, and its heating value differs in every 
town. The amount of air used to dilute the charge is also an 
element of uncertainty in making calculations. The ordinary 
method is to measure the quantity of gas entering the cylinder 
by a meter, and to calculate the air consumption from the 
total volume, but this is an unsatisfactory plan. A certain 
amount of the products of combustion almost always remain 
in the cylinder, mixing with the fresh charge, and as the 
quantity of gas admitted does not vary, they roust reduce the 
proportion of air entering with it. The quantity of air should 



THE UTILISATION OP HBAT IN A OA8 ENGINE. 235 

be actually measured, and this has been done bj Dr. Slabj and 
others. 

Expansion. — The utilisation of heat in a gas engine, and its 
transformation into work, is mainly obtained during the two 
processes of expansion and compression. The uses of compres- 
sion, and the great advantages derived from it, have already 
been explained. It reduces the original volume of the gases, 
and increases their power of expansion. But since the temper- 
ature obtained by explosion in a gas engine is high, the expan- 
sive force of the gases is correspondingly high, and is never 
completely utilised. The gases are always discharged into the 
atmosphere at a considerable pressure, which, had it been 
possible to prolong the stroke indefinitely, might be turned to 
useful account in doing work upon the piston. It is on account 
of this high expansive energy of the gases, that most modem 
writers insist upon ignition at the dead point. The whole heat 
is added, and explosion takes place as far as possible at constant 
volume, or before the piston has moved, and thus the whole 
volume of the cylinder is available for the expansion of the 
gases. 

Engineers usually employ four kinds of Efficiencies, to repre- 
sent the utilisation of heat and power in an engine. 

L The first is known as the Maximum Theoretical Efficiency 
of a perfect engine, and is defined in the preceding chapters. 

T - T 
It is expressed by the formula, — ^= — o, and shows the working 

Ii 
of a perfect engine between these limits of temperature (T^ 
and To). 

II. The second is the Actual Heat Efficiency, or the ratio of 
the heat turned into work to the total heat received by the 
engine. 

III. The third is the ratio between the second (actual heat 
efficiency) and the first (maximum theoretical efficiency). It 
represents the maximum proportion of possible heat utilisation 
actually obtained by the engine. 

lY. The fourth is the Mechanical Efficiency. It is the ratio 
between the useful horse-power (or brake H.P.) available at 
the end of the crank shaft, and the total indicated horse-power. 
The difierence between the two is the I.H.P. necessary to drive 
the engine itself. Suppose an engine indicating a total of 100 
H.P., and that by a special experiment it was found that 20 
H.P. was required to keep the engine going at the same speed, 
without any external work. In such a case the mechanical 
efficiency would be 80 per cent. Examples of these important 
different efficiencies are given in Professor Capper's tests (p. 364), 
also by Miller "On Efficiencies," and by other writers on the 
subject. 

Ideal Diagram. — The diagrams representing the area of work 



236 



OAS BN0IKE8. 




Fifr 101. 



-Diagram of Perfect Cycle with 
(Jompression. 



in a heat engine are similar to that of Carnot's perfect cycle, 
but vary in shape according to the type of motor, and the 
curves produced by the pressure, expansion, and cooling of 
the gases. Fig. 101 represents a perfect cycle, in which the 
gases are compressed before ignition. The line A B is the 
abscissa, and is proportionate to the cylinder volume and 
the length of stroke. The line D F is the ordinate of pressure, 
and the mean height of the area D F B C D gives the mean 

pressure. Explosion takes 
place at D, the pressure 
rising instantly to F with- 
out change of volume, as 
the piston is stationary. 
From F to B the charge 
expands, and all the work 
of the engine is done. The 
pressure and temperature 
fall in consequence. From 
B to A the gases are dis- 
charged at atmospheric 
pressure. The piston 
draws in the charge from 
A to B and compresses 
it into the clearance space. 
In this ideal diagram all the lines follow Carnot's cycle. 
Compression and explosion are both adiabatic, that is to say, no 
heat is lost, but all is transformed into energy, and again 
refunded by compression of the charge. The gases also expand 
till their pressure falls to atmospheric, and their whole energy 
is supposed to be utilised. The diagram is formed of two 
adiabatic lines, compression and expansion ] a vertical explosion 
line with no increase in volume during the rise in pressure, 
and a horizontal exhaust line, with no back pressure during 
the return to the original volume. 

Actual Otto Diagram. — We will -now consider what really 
takes place in an engine, and the area of work shown by an 
indicator diagram. Fig. 102 is an actual indicator diagram 
taken at a trial of an Otto engine by Messrs. Brooks & 
Steward, and similar to most modern diagrams. Here A B is 
the line of atmospheric pressure, and almost parallel with it is 
the line of admission, A 0. It will be remembered that in the 
Otto cycle, the piston draws in the charge during one entire 
forward stroke. If the lines A B and A be compared, the 
latter will be seen to be rather lower, showing that there is a 
small vacuum in the cylinder, and the charge is admitted at a 
pressure slightly below that of the atmosphere. From C to D 
the charge is compressed, the pressure rises, but the line falls 
below the adiabatic (compare C D in Fig. 101). Evidently the 



THE UTILISATION OF HEAT IN A OAS ENOINE. 



237 



heat is carried off and abstracted by the cooler walls, as well as 
stored up by the compression of the gas. From D to F is the 
explosion line, which also deviates &om the perfectly vertical 
line in Fig. 101. The top of the diagram is rounded, showing 
that the piston had begun to move a little before explosion was 
complete ; the pressure did not at once attain its maximum, nor 
was combustion complete when the highest pressure was reached. 
The line of expansion F G differs from the true theoretical 
adiabatic curve. Various circumstances, such as after com- 
bustion, and also the cooling action of the walls, contribute to 



Artital /n diealo r 
Otto Kfictnt. 

't^Strok*. 




J Atlmirrion. 
\<. ThtJfUnfrth {» proportumal to th€ strokt qf EtigHie. "M 

Fig. 102. — Otto Engine — Actual Indicator Diagram. 
(The figures indicate sequence of operations.) 

alter the shape of the expansion curve in actual gas engines. 
At G a phenomenon occurs, with which nothing in Fig. 101 
corresponds. The exhaust valve opens prematurely, while the 
gases are still at a high temperature and tension, and the 
pressure falls suddenly, before expansion is completed; the gases 
escape into the atmosphere, instead of continuing to act upon 
the piston. At H the end of the stroke is reached, and the 
gases of combustion are discharged along the return line from 
H to A. At the beginning of the return stroke this line is 
above the atmospheric pressure to which the gases are in theory 
reduced at the end of expansion, and there is a certain amount of 
back pressure, or pressure retarding the motion of the piston. 

This indicator diagram may be taken as a typical representation 
of the curves of pressure usually obtained in an Otto engine 
during two revolutions. The chief reasons for the variations 
in this, as compared with a theoretical, cycle, are : — 

1. Explosion is not instantaneous, and continues after the 
piston has begun to move out. 

2. Combustion is not completed till some time after the 
beginning of the stroke, and the whole heat is not developed 
instantaneously. 

3. Heat is carried off by the walls and the water jacket to 
reduce the temperature within practicable limits. 



238 GAS ENGINES. 

4. Expansion is never adiabatic, and the whole heat expended 
or evolved from the gas is not absorbed in doing work. 

5. Expansion is not continued till the pressure of the gases 

is reduced to atmospheric, but they are discharged much before 

their full pressure has been utilised in work on the piston. 

T - T 
Although the formula -^7^ — ^ applies equally to all heat 

engines, there are various types of gas motors, each utilising 
differently the heat supplied. In practice they are classified 
under four heads. In each of these types the indicator diagram 
varies slightly in shape, and the actual efficiency may be ex- 
pressed by a different formula. The formulae of efficiency now 
generally used in calculating the work obtained in theory from 
a gas engine were originally drawn up by Professors Schottler 
and Witz, and Mr. Dugald Clerk, from whose able generalisations 
the following figures are taken : — 

Fommlfle for Effloienoies. — The first three types of gas 
engines are direct acting, and the heat supplied acts directly by 
expansion of the gas upon the piston; the fourth is indirect 
acting, the expansion of the gases forces up the piston, but no 
work is done except during its descent The formula for calcul- 
ating the maximum theoretical efficiency is, as already given, 

T — T 

^= — ^, in which T^ represents the highest absolute tempera- 

ture attained by the gases, Tq the temperature (absolute) to 

T - T 

which they fall after doing work on the piston, and 1 ^p — ^ 

-■•1 
the percentage of heat utilised. The same formula may be 
differently stated, thus — 



_Q_^ 



1 +n 



= c (Ti - To) 



or — ^The total quantity of heat developed by the explosion of the 

gases (Q) divided by the weight of the charge (1 of gas plus n 

dilution of air) is equal to the highest absolute temperature of 

the gases, T,, less the lowest absolute temperature, Tq, multiplied 

by their specific heat at constant volume, e^ The specific heat 

of the gases at constant volume is taken, because it is assumed 

that the whole of the heat is added before the piston has moved. 

From the quantities of heat the pressures can be deduced accord- 

T 
ing to Boyle's law. Thus p^ = p^ J or — The highest pressure, 

■*-o 
p^ developed by the explosion of the gases is equal to the initial 

pressure, p^ multiplied by the ratio between the highest and 

lowest absolute temperatures. In the following formulae the 

pressures are omitted, but they can be worked out by the student 

from the temperatures. 



THE UTILISATION OF HEAT IN A GAB EKGINB. 239 

1. The first type of gas motor is the direct-acting non- 
compression engine. Here the gases are not compressed before 
ignition, but are admitted into the cylinder at atmospheric 
pressure and ordinary temperature. All the heat is then 
generated at once, and the gases expand, driving the piston 
to the end of the stroke. The best example of this sequence 
of operations is furnished by the original Lenoir engine (see 
diagram, p. 35). In its cycle there are three important tem- 
peratures— -T^ the initial temperature of the gaaes admitted into 
the cylinder, T^ the highest temperature during explosion, and 
Tji the temperature of the gases at release, after they have done 
work on the piston. In theory Tj should be equal to T^ — ^that 
is, the gases should be reduced to their original atmospheric tem- 
perature. In practice this is never possible, but they are always 
discharged at a higher temperature than T^ Q represents the 
•quantity of heat added from the source of heat (in heat units or 
ciedories), Q« the quantity discharged to the exhaust, Q« the 
quantity turned into work, and y the ratio between the specific 
heat of the gases at constant volume (c,) and at constant pressure 
<c,). Thus— 

Q = c-(T, -To). 

The formula for actual efficiency E of this class of engine 
is: — 

R - c,(Ti -To)-<»(Tt-To) _ _ / T,-To \ _ , Q. 

2. In the seoond type of engine the gases are compressed be- 
fore ignition, and explosion takes place at constant volume. To 
the three temperatures given above, and always to be taken into 
■account in estimating the heat efficiency of any engine, the 
•compression of the gases before ignition adds a fourth, T3 = 
temperature of compression. Work being done on the gas by 
-driving the particles closer together, heat must be developed. 
This rise in temperature is calculated by multiplying the original 
temperature, T^ by the difference in the volume of the gases 
before and after compression, raised to the power of the ratio 
'Of the specific heats minus 1. The temperatures are here ob- 
tained from the volumes, according to Boyle's law. The formula 
for calculating this temperature of compression is — 

L l^iOS - 1 - -408. 



'-^•(?) 



where v^ is volume before compression, v^ is volume after com- 
pression. The Otto four-cycle engine is the best example of 
this type (see diagram, pp. 92, 93). Thus — 

Q = c(Ti-Ta) Q. = ft» (T,- To) Qo = Q-Q^ 



240 GAS RNOINB8. 

The actual efficiency of this type is — 

p __ c(Ti-T3 ) -Cp(T2-T o) _ _ /T,-To\ . , Q. 

3. The third type represents an engine in which the gases are 
compressed before ignition, as in the second type, but instead of 
exploding, they burn at constant pressure. They enter the 
cylinder as flame, and drive the piston forward, not by the force 
of the explosion, as in the two former types, but by the expan- 
sion of the burning gases. It seems at iirst as though this type 
ought, in accordance with the theories hitherto laid down, to 
give a very low efficiency — that is, to utilise a very small pro- 
portion of the heat supplied to it, becau8e there is a constant 
temperature of combustion during the forward stroke, instead of 
an instantaneous temperature of explosion. The highest tem- 
perature attained is not very great, and there is less raoge than 
in the other types. It is, however, an engine giving excellent 
results in theory, and it is difficult to understand why these 
results are not realised in practice. The working defects are 
attributed chiefly to insufficient compression. The efficiency 
depends, not on the highest temperature attained, but upon the 
amount of compression, and the greater the compression the 
greater the heat. In this class of engine, therefore, the usual 
rule is reversed, and an efficient cycle is obtained with a low 
temperature of explosion, T^. The best example of this type is 
the Simon engine (see p. 53). In the formula the ratio of specific 
heat does not appear, because the burning gases are at a uniform 
temperature throughout the stroke, and all the operations are 
efiected at constant pressure. 

Q = Cp(Ti-Ta) Q. = <v(T,-To) Qc = Q-Q^ 

Ffflni««P,r V - gp(Ti-T,)-Cp(T,-To) _ /T, -To\ _ p _ Qc 
Efficiency E- c{T,-T,) " ^ " Vt,— r,) = ^ = Q- 

4. Atmospheric Gkts Engines. — To this class belong engines 
in which the action of the gas upon the piston is indirect, and 
work is obtained, not by expansion, but by the formation of a 
vacuum under the piston. Theoretically, this type is the most 
perfect of all, because of the high explosion ])ressure, and the 
apparently unlimited expansion, but this great expansion can 
never be utilised in practice. A piston of undefined length, 
permitting the gases to expand until their pressure falls to atmo- 
sphere, would be necessary to utilise fully the power developed, 
and this is impossible under working conditions. As the gases 
are not previously compressed, there is no temperature of com- 
pression, but anorlier temperature must be reckoued, T4, repre- 
senting the temperature of the gases after the exhaust has 
opened^ but before they are compressed by the atmosphere, and 



THE UTILISATION OF HEAT IN A OA8 ENGINE. 241 

restored to their original condition. The heat quantities are 
represented by — 



Efficiency E = I- g;-^J;) = I 



These formulae will be best understood, if calculated and 
expressed in figures. The temperature of explosion in most 
gas engines is usually taken at from 1000° 0. = 1273** Abs. 
to 1600° C.= ISTS' Abs. The initial temperature is commonly 
assumed to be from about 12* C. = 285° Abs. to 18^ C. = 29V Abs. 
Tbe initial atmospheric pressure is taken at 14*7 lbs. per square 
inch ; the volume of the cylinder is reckoned in cubic feet or 
cubic metres. In an experiment made on a 4 H.P. Otto engine 
by Dr. Slaby, the absolute temperatures were computed as 
follows : — 

Initial temperature, To, 400° C. 

Temperature of explosion, . - '^n 1^04** C. 

Temperature at the oi)ening of exhaust, T^, 1068** C. 

Temperature of compression, . Tj, 400^ C. 

The actual efficiency calculated numerically (see formula of the 
second type) is 



„ __ 192 (1504*'-400°) - 0264 (1068°-400°) _ , ,.,.7- /1068"-400^\ 
0192 (1604* - 400*) " '^ Vl504*-4007 

or 

E = ^^^^ii'-Q^^'^ » 0168 = 1 - 1-375 X -605 = 17 per cent. 

From the above formulae of efficiencies it is evident that, in 
order to obtain a sufficient fall in temperature, it is of great 
importance to keep the initial temperature of the gases low. 
In theory the efficiency of the engine depends on the range of 
temperature, and the lower the initial temperature, and the 
higher it can be raised by explosion the better. Much stress is 
therefore laid by all authorities upon introducing the gases into 
the cylinder at as low a temperature as possibla The utilisation 
of the heat in theory depends on the difference between the 
maximum temperature and the temperature of admission. In 
practice, however, the hotter the gases (after explosion), the 
greater will be the difference in temperature between them and 
the cylinder walls ; consequently the waste will also be greater, 
because they will part with more heat t6 the water jacket. To 
obtain an economical working cycle, all losses of heat should be 
reduced as much as possible. These are, the ex|)osure of a large 
area of cylinder surface to the hot gases, and length of time 
during which the exposure lasts. The causes to which waste of 
heat are attributed will be studied in the next chapter. 

16 



242 



OAS ENGINES. 



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RXPLOSIOH ASV COKBDSTION IH A QAS KNOIHX. 243 



CHAPTER XIX. B 

EXPLOSION AND COMBUSTION IN A GAS ENGINE. 

GoxTBtTTs. — ^Dafinition of Terms — Rate of InflamTnability in Gases — ^Bansen, 
Mallard and U Chatelier, Berthelot and Vieille, Witz, Clerk— Wall 
Action — Equilibria m of Heat — Stratification — Dissociation — Wall 
Cooliog— Increase of Specific Heat— Cylinder Wall Action. 

Thb phenomena taking place and work obtained in a heat 
engine have now been shown to depend on the development 
and utilisation of heat. Since heat in the cylinder is obtained 
by the ignition, explosion, and combustion of a certain quantity 
of air and gas, the character of these phenomena, the strength of 
the explosion, and speed of propagation of the heat through the 
gas, are of the utmost importance. For many years they have 
engaged the attention of scientific men. By careful study and 
observation, a sufi&cient number of exact experimental facts have 
been accumulated to determine with precision the action of gas 
in an engine cylinder. 

Definition of Terms. — Before proceeding to consider these 
phenomena, it will be well to define the different expressions 
generally used. Four terms are employed to denote the effects 
produced by heat in the cylinder of a gas engine — 1, Ignition ; 
2, explosion ; 3, inflammation ; 4, combustion. Ignition takes 
place when sufficient heat is communicated by a flame, electric 
spark, or hot tube to the gaseous mixture to fire it. Inflamma- 
tion is the subsequent spreading of the flame throughout the 
gas, or its propagation from one particle to another, till the 
whole volume is alight. Explosion follows when the mixture 
is completely inflamed, and the maximum pressure attained* 
When all the gas in a cylinder is thoroughly alight, the particles 
are driven widely apart, and thus the moment of complete in- 
flammation will also be that of maximum pressure. Complete 
inflammation and explosion are thus practically simultaneous. 
Combustion is complete when all the chemical changes have 
taken plaoe, and the gases have been reconstituted as water 
vapour (HjO) and carbonic acid gas (COg). This moment may 
not coincide in point of time with explosion. The chemical 
recombination of the gases, and consequently the evolution of 
all the heat contained, is almost always delayed in a gas engine 
until an appreciable time, or fraction of a second, afler the 
maximum pressure is developed, and the piston has begun to 
move out, as shown by the indicator diagram. 

Velocity of Flame Propagation— Bunsen. — It is at the 



244 GAS ENGINES. 

moment when explosion occurs that the maximum pressure is 
reached, and probably also the maximum temperature.'^ The 
importance of this temperature has been proved theoretically in 
the preceding chapter, and many experiments have been made to 
determine it, because it marks the rate of inflammation, or of 
propagation of the flame. The celebrated chemist, Bunsen, 
was the first to calculate the rate of flame propagation — or of 
inflammability — in a gas. He confined the mixture in a vessel 
having a very small orifice, and the gas was ignited as it passed 
out. The mouth of the orifice was reduced tUl the pressure of 
the issuing flame was exactly equal to that of the gas inside, 
and as soon as the balance of pressure was established, the 
flame spread back till it had ignited the gas in the vessel. The 
method of ignition used in the Koerting engine is somewhat 
similar. The rate at which the gas issued from the vessel being 
known, the speed of the flame, as propagated back through the 
mixture, was calculated from it. By these means Bunsen 
determined the velocity of propagation, or the inflammability 
of a gaseous flame. With a mixture of 2 volumes hydrogen 
and 1 volume oxygen, he found it to be 34 metres = 111*5 feet 
per second ; with carbonic oxide it was 1 metre = 3*28 feet per 
second. 

Mallard and Le Chatelier. — Later researches have shown 
that these figures are not accurate. The instrument then used 
could not be wholly relied on, because the external air cooled 
the flame as it issued from the orifice, and aflected the results. 
A series of elaborate experiments have been conducted by MM. 
Mallard and Le Chatelier with a long tube filled with an explo- 
sive mixture, closed at one end, and communicating through the 
other with the open air. The period of explosion, or the time 
occupied by the flame in travelling through the tube, was marked 
by revolving drums and tuning forks, the latter being the best 
instruments for measuring, by their vibrations, fractions of 
a second. The drums revolved on the same shaft, close to 
either end of the tube, and a wavy line was traced upon them 
by the vibrations of the tuning forks, set in motion by the explo- 
sion. As soon as the gas at one end of the tube was ignited, it 
moved a small pencil, and marked the drum revolving at that 
end. A second pencil made a similar mark on the drum at the 
other end, when the flame had passed through the length of the 
tube. The distance between the two marks, measured on the 
vibrating line traced by the tuning forks, gave the time of pro- 
pagation of the flame. With the same mixture of hydrogen and 
oxygen as that used by Bunsen, Mallard and Le Chatelier found 
the velocity to be 20 metres = 65*6 feet per second, and with 

* Dr. Slaby says that " combustion is completely ended after a fractional 
portioQ of the stroke, from 0*03 to '06 of a second." — Calorimetriach€ 
urUersuchungen^ p. 161. 



EXPLOSION AND COMBUSTION IN A GAS ENGINE. 



245 



carbonic oxide 2-2 metres = 7-2 feet per second, or a speed 
double that given by Bunsen. 

These pure explosive mixtures are too strong to be used in a 
gas engine, as air is necessary to dilute the gas, and the mixture 
becomes immediately weakened with a large proportion of non- 
explosive nitrogen. MM. Mallard and Le Chatelier, therefore, 
varied the strength of the mixture. With I vol. hydrogen mix- 
ture (i.e., 2 vols, hydrogen to 1 of oxygen) and 1 vol. oxygen, 
the rate of flame propagation was 10 metres ■= 32*8 feet per 
second. The highest velocity was found to be the mixture of 1 
vol. hydrogen to 1 vol. oxygen, originally used by Bunsen, but 
to obtain a standard for the dilution commonly employed in a 
gas engine, the experimenters combined hydrogen with air in 
the proportion of 2 vols, hydrogen to 6 of air. The following 
table (from Clerk) shows the velocity of flame with hydrogen 
and various volumes of air : — 



Tablb of Velooitt in Diluted Mixtubes {MdUftrd and Le CAote^ter). 





Vrioolty 


Vrtod^ 




fttHaeoai. 


per Second. 


Mixture of 1 vol. hydrogen and 4 vols, air 


2 metres. 


6-5 feet. 


.. ,.3 ., 


28 „ 


91 ,. 


,, 2 „ 


34 „ 


Ill „ 


„ 1 ,. 


41 .. 


13-4 „ 


• 1 >i » » 1: » 


4'4 „ max. 


14-4 ,,max. 


, 1 „ 


3-8 „ 


12-4 „ 


,. i ,. 


2-3 ,. 


7-5 „ 



In these experiments the explosive mixtures were at constant 
pressure; the end of the tube being open, the ignited gases 
issued from it in a continuous stream, and did external work 
Against the pressure of the atmosphere. When both ends of the 
tube were closed, and the mixture was ignited at constant 
volume, the velocity with which the flame was propagated was 
very much greater. A speed of 1,000 metres = 3,280 feet per 
second, instead of 20 metres, was verified with hydrogen explo- 
sive mixture (2 vols. H and 1 vol. O). When the hydrogen 
was diluted with air, the speed was 300 metres = 984 feet per 
second. This great difference in the rate of flame propaga 
tion is attiibuted by MM. Mallard and Le Chatelier to in- 
flammation taking place, not only by the projection of the 
flame from one particle to another, but by the expansion of 
the particles through the heat generated. As they ignite, they 
rise in temperature and pressure, and the propagation of the 
flame is thus assisted. When the mouth of the tube is closed, 
and the particles cannot expand freely into the atmosphere, the 



246 OA8 ENGINES. 

ignited portions of the gas are forcibly projected into the parts 
not yet kindled. These experiments prove the greatly increased 
velocity of flame propagation when the volanie of the gases is 
constant, and therefore the value of ignition at the dead point 
in a gas engine. The maximum explosive pressure is higher 
and more rapidly obtained, when the piston is statiouary. 

Berthelot and Vieille. — A series of valuable experiments 
were also carried out by MM. Berthelot and Vieille, to determine 
the rate of flame propagation (or of complete combustion, since 
in this case the two t^rms are synonymous) of gases at constant 
volume in a closed vessel. The time of explosion was determined 
in receivers of three different capacities — namely, 300, 1500, and 
4,000 cubic centimetres. Two of the vessels were cylindrical and 
the third spherical, and each was fitted with a registering piston. 
At either end they terminated in a short tube; at the further 
end of one an electric spark was produced for firing the mixture, 
the other contained the piston. The lengths of the igniting 
tube, the cylinder, and the tube containing the piston being 
known, the time occupied by the flame in passing through the 
gas, from the point of ignition till the explosion reached and 
forced u[» the piston, could be calculated. The experiments were 
made with a variety of chemical compounds, such as bioxide of 
nitrogen, cyanogen, and compounds of hydrogen, oxygen, carbon, 
and nitrogen. The larger the capacity of the vessel or receiver, 
the longer time was found to elapse, with every mixture, between 
the ignition of the gas, and the attainment of maximum pressure. 
This agrees with Gay Lussac's law, since the smaller the vessel 
and the volume of the gas, the greater will be the increase in 
pressure produced by the high temperature of ignition. The 
effect of the composition of the mixture, and of the more or 
less perfect combustion obtained by adding oxygen in exact 
proportion or iu excess, were also noted. 

But one of the most important practical results of these ex- 
periments, with regard to the phenomena in a gas engine, was 
obtained with the products of combustion. By using a mixture 
of the chemical elements contained in these ])roducts, and ob- 
serving the time occupied by the projection of the flame, MM. 
Berthelot and Vieille proved that the rate of flame propagation 
in such compounds was slower than with pure mixtures, repre- 
senting the fresh charge of gas and air in a cylinder. Dilution 
with the products of exhaust, therefore, whether advantageous or 
not, must retard the rate of combustion, because these products 
contain an excess of some of the gases. With gases not perfectly 
combined, and where combustion is incomplete, the rate of flame 
propagation was found to be most rapid, perhaps because 
partial dissociation takes place and retards total combustion. 
MM. Berthelot and Yieille are of opinion that, by the igni- 
tion of the gas and the high temperature produced in the closed 



XZPLOSIOK AND COMBUSTION IN A OA8 ENQINK. 247 

vessel, what they term an "explosive wave" is formed, the 
velocity of which is greatly in excess of the ordinary velocity 
of flame propagation. They call it the rate of detonation. The 
explosive wave is generated by the shock of igniting a large 
portion of the inflammable gas at once ; the flame is propagated 
with a velocity due to the shock, almost as great as the velocity 
of combustion. For hydrogen the velocity of this explosive 
wave is 2,810 metres = 9,216 feet per second ; for carbonic 
oxide it is 1,689 metres ^ 5,539 feet per second. 

Begarding the time of attainment of maximum pressure during 
explosion at constant volume, they say : — ^' The variations in thia 
time are very important. The maximum pressure observed in 
a vessel of any given capacity is always less than the pressure 
which would be developed, if the system retained all the heat 
due to chemical reaction, for there is always a certain loss from 
contact with the walls and radiation. The smaller the quantity 
of gas in proportion to the vessel containing it, and the more 
slowly combustion takes place, the greater is this difierence. The 
time occupied by combustion varies much ; it corresponds to the 
different conditions developed at the beginning of the phenomena,, 
and is intermediate between the velocity of the explosive wave, 
and the ordinary velocity of flame propagation of any given gas.*^ 

Wits. — Valuable as these theoretical determinations are in 
studying the theory of combustion, practical experiments are 
needed to calculate the actual result of generating heat in a gas, 
by combustion in an engine cylinder. With this object, Pro- 
fessor Witz undertook a number of valuable experiments to 
illustrate the action of ordinary lighting gas, when mixed with 
various proportions of air, and ignited. He also desired to show 
the influence of nitrogen in affecting injuriously the true rate of 
flame propagation. In MM. Berthelot and Yieille's experiments, 
the gas was always at constant volume, and no expansion was 
possible. M. Witz used an ordinary cylinder and piston, and 
the charge was allowed to ex))and freely. The first tests were 
made, not with lighting gas, which varied too much in composi- 
tion to give accurate results, but with a mixture of carbonic 
oxide and air ; the calorific value at given temperatures of each 
chemical element was previously determined. A basis bi'ing 
thus obtained for exact computation, lighting gas was used for 
the rest of the trials, and the differences in chemical composition 
neglected. Professor Witz attached a tuning fork to the indi- 
'cator diagram, in order to measure, not only the pressure 
developed by the explosion, but the fractions of a second before 
the maximum pressure was attained. Taking the ratio of this 
time to the length of stroke of the piston, he reckoned the speed 
of expansion thus — 

Length of stroke in feet • . • • < ^ ^ 

T^ — ^, g i — : — ; 3- = spced of expsiiBion m feet per leoond 

Duration of exploeion m Beoonda •^ ' *^ 



248 



GAS ENGINES. 



Calculating the work done from the area of the diagrams, and 
its ratio to the theoretical work obtained from the number of 
calories in a given volume of gas and air, Professor Witz found 
that the percentage of work actually done increcwed in proportion 
to the speed of expansion. Some of the results of his able 
experiments made with lighting gas mixed with varying propor- 
tions of air, are summed up in the following table : — 

EXFEIUMKNTS OF PrOFBSSOB WiTZ ON ToWN GaS, WITH CONSTANT 

MixTtTRE OF 1 Volume Gas to 9*4 Volumes Ahl 
[Vol. of mixture, 2 081 litres.] 



[1 Litre = 61*025 cab. ins.] 

Mixture of 1 Volume Gas to 6*33 Volumes Air. 
rVol. of mixture, 2*081 litres.] 



633 
633 
633 
633 



015 


259 


1*7 


0*09 


259 


2*9 


0*06 


259 


4-3 


006 


259 


4*8 



17*6 


2*7 


40*1 


6*2 


50-5 


7*9 


50 7 


9*3 



In both these series of experiments the volume of the charge 
was the same — namely, 2 081 litres = 0*73 cubic foot The 
richness of the mixture, the length of stroke, and the dura- 
tion of the explosion varied. Fig. 103 shows a diagram of the 
expansion, with the vibrations below of the tuning fork used 
as a measure of time. Each vibration corresponds to -j-^ of a 
second. The diagram gives the pressures and volumes, the 
lower waves mark the time occupied in expansion. The atmo- 
spheric line, Ho:, shows that expansion was continued to below 
atmospheric pressure. From these and many similar experi- 
ments, Professor Witz has formulated the two following laws 
concerning the expansion of gases : — 



* Kilofframmetres mean kilogrammes x metres = 2*1 
ft. lbs. olwork done (see p. 211). 



I lbs. X 3*28 ft or 



Damtion of 
Bzploiioii in 

Seeond, taken 
fromDU. 


Lemrthof 

Stroke of 

Piaton. 


Speed, 

Metres per 

Second. 


Theoreiieal 
Work. 


Work ealea- 

Uted from the 

Diagrams. 


UUUsation or 
Per Cent of 
Work done. 
Batio of ool- 

nmnstfande. 




grams. 


1 












a. 


b. 


a 
Metres. 


d. 


«. 


e 
d 




Second. 


Millimetret. 


Killoffram- 
metms.* 


Killogram- 
metres. 


Percent 




0-48 


122 


0-25 


446 


5 3 


1-2 




047 


127 


0*27 


446 


53 


1-2 




0*40 


127 


0*32 


446 


70 


1*5 




0*39 


132 


0*34 


446 


6*6 


1-4 




0-31 


140 


0*45 


446 


7-8 


1*7 




0-23 


147 


0-64 


446 


10*8 


2*4 





EXPLOSiOX AND COMBUSTION IN A GAS ENGINE. 



249 




Fig. 103.— Witz' Time Diagram. 



I. The utilisation of the heat supplied to the engine increases 
with the speed of expansion. 

II. The greater the speed of expansion, the more rapid will be 
the combustion of the explosive mixtures. 

This speed of expansion, which the above table shows to have so 

important an effect on the proportion of actual to theoretical work, 

Professor Witz considers 

to be only the expression 

under another form of 

the great influence of the 

walls, and their cooling 

action upon the hot gases. 

'^ The maximum explo- 
sive pressure," he says, 

" depends on the ratio of 

the cooling surface of the 

receiver (or cylinder) to 

the volume of the gas." 

In his opinion, nearly all 

the differences between 

the action of the gases, in theory and in practice, in the cylinder 

of an engine, which have hitherto been so difficult to account 
for, may be attributed to the effect of the walls. 
Clerk. — Mr. Dugald Clerk was led by his experiments to 

almost the same conclusions as Professor Witz, though he 

approached the subject from another point of view. He con- 
sidered that, to understand the action of gas in a cylinder, it was 
necessary to determine not only its rate of explosion, that is, the 
time required to attain maximum pressure, but also the duration 
of this pressure. It is the force of the explosion which ]>roduce8 
effective pressure on a piston. It seems therefore as if, the 
stronger the mixture employed within working limits, the more 
useful will be the effect, but experiments have shown this view 
to be erroneous. The greater amount of work is obtained, not 
from the most explosive mixture, but from that giving the 
maximum pressure in proportion to the surfaces, and maintain- 
ing that pressure during the longest period of the stroke. Since 
radiation cannot be prevented, the higher the explosive pressure 
and temperature generated, the more rapidly will the heat be 
carried off by the walls of the cylinder, and the pressure oorre- 
Bpondingly reduced. This is one reason for the difference 
between theory and practice in an engine cylinder. Theoreti- 
cally the highest explosive pressures are the best ; but in practical 
working they are not found the most effective for power. 

Mr. Clerk's experiments were made with a small cylinder 
without a piston, filled with different explosive mixtures, to which 
an indicator was connected. The indicator drum and paper were 
made to revolve so that each tenth of a revolution occupied 



250 GAB ENGINES. 

0*033 second. The pressure of the explosive gases forced up the 
indicator pencil, causing it to trace different curves on the moving 
drum. By dividing the area of the drum into sections, the time 
occupied by the explosion, and cooling or reduction of pressure 
of the gases, could be estimated within y^ of a second. On 
this diagram the ordinates represented pressures, as usual, 
and the abscissae the time of explosion in fractions of a second. 
The conditions under which gases explode in the cylinder of an 
engine were reproduced in all but two respects. Under ordinary 
circumstances the piston in a gas engine uncovers during the 
stroke fresh portions of the cooler walls to the hot gases, and the 
explosive pressure is rapidly lowered. Here the maximum 
explosive pressure was developed in a closed vessel, and, there- 
fore, at constant volume ; and the cylinder having no piston, no 
heat was expended in doing work. The conditions were similar 
to those of an engine before the piston has moved. 

Mr. Clerk gives several diagrams showing that the pressures 
of the gases fell much more slowly than they rose. The 
maximum pressure was produced in 0*026 second after ignition; 
the fall to atmospheric pressure and temperature occupied 1*5 
second, or nearly sixty times as long. Without previous com- 
pression of the gases, the highest pressure obtainable with a 
dilution of 1 part gas to 5 parts air (that is, the mixture con- 
taining just enough oxygon to produce combustion of the gas) 
was only 96 lbs. per square inch. With compression and a much 
weaker mixture, this pressure was nearly doubled. Mr. Clerk 
proved that the ** critical mixture," or the weakest dilution of 
gas and air that will ignite, varied according to the quality of 
the gas used. With Oldham gas a charge of 1 part gas to 15 of 
air ignited, and the pressure produced was 40 lbs. per square inch 
above atmosphere. With Glasgow gas the critical mixture was 
14 of air to 1 of gas, and the pressure produced was 52 lbs. per 
square inch. 

To determine the best and most serviceable mixture for use in 
a non-compressing gas engine, the following calculations were 
made. Mr. Clerk supposed 1 cubic inch of gas to be diluted 
with air in the ratio of 13, 11, 9, 7, and 5 cubic inches, and these 
mixtures to be admitted into cylinders having pistons, the areas 
of which per square inch were in proportion to the strength of 
the dilution. Thus the charge of 14 cubic inches — viz., 1 volume 
gas to 13 volumes air — would be admitted into the cylinder 
having a piston surface of 14 square inches. The mixture of 
6 cubic inches would be contained in^the cylinder having a 
square piston area of 6 inches, and the depth of the mixture in 
the cylinder would always be 1 inch. The maximum pressure 
of these mixtures he had already determined, as well as their 
time of explosion, by the instrument mentioned as shown in the 
following table : — 



EXPLOSION AND COMBUSTION IN A GAS ENGINE. 



251 



EXPSBTMBNTS BY Mb. ClSBK ON EXPLOSION AT CONSTANT VOLUME IN A 

Closed Vessel without Piston. Mixtures op Aib and Glasgow 
CuAL Gas. 



If iztares uwed. 



Mazimnm Presrare 

ftbove Atmosphere in 

lbs. per eq. Inch. 



iTImit of EzploKlon, 

or time elupBfiig between 

ICnUion Hiiit Meximum 

Prfseure. 



1 Yolame plus 13 volumes, 

* f» »> ** »» 

* »» »» «' »» 
I »» i> ' i> 
1 » i* 5 „ 



52 lbs. 
63 „ 
69 „ 
89 „ 
96 .. 



0-28 second. 
018 „ 
0-13 „ 
007 „ 
005 „ 



Temperature before ezplosion* 18** C. = 291° Abs. Pressure before 
explosion, atmospheric. 

By these and other experiments Mr. Clerk found that the 
highest pressui-es, giving respectively 756 lbs. and 728 lbs. upon 
the total piston area, were obtained with a dilution of 1 1 and 13 
volumes of air to 1 of gas. The stronger mixtures gave lower pres- 
sures, because, being contained in smaller cylinders, the pressure, 
to a uniform depth of 1 inch, was exerted over a smaller piston 
surface. The rate of cooling, or of &11 in pressure, was calcu- 
lated in the same way. Taking one-fifth of a second as the 
mean time occupied by the piston in making its forward stroke, 
the pressure of each gas when that time had elapfted, after the 
attainment of maximum pressure, was computed from the indi- 
cator diagram. Multiplying this pressure by the piston area, it 
was found that the weakest mixtures gave the highest relative 
pressure at this point in the stroke, showing that these weak 
mixtures maintained their pressure longest. The following table 
exhibits the results for five different dilutions : — 

EXPXBIHEKTS BY Mr. ClERK ON MiXTUBBS OP AlR AND GLASGOW GaS 

AT Constant Volume {with §ame JpparcUw), 



Hixtnre. 



Pressnre pro- 
duced on 
rieton by 1 
enb. in. gas. 



Preeanre In 
Ibe. per sq. 

in., 0.0 
eeoond after 
max. pre«e. 



Prersure 
rem.Uning 
np« II piston 
area 20 sec. 
after mnz. 
pressuie. 



Mean 
Preaaors. 



Yol. gas plus 13 vols, air 

>> i> 1* »» 

»» » • >i 
«. .t 5 ,, 



728 lbs. 
756 „ 
690 „ 
712 „ 
576 „ 



43 lbs. 
48 „ 
47 „ 

56 „ 

57 „ 



602 lbs. 
576 „ 
470 „ 
440 „ 
342 „ 



665 lbs. 

666 „ 
580 „ 
576 „ 
469 „ 



Mr. Clerk also made experiments with pure hydrogen diluted 
with air, but found the pressures much lower than with gas. 



252 GAS ENGINES. 

The best mixture, 1 volume hydrogen to 5 volumes air, gave a 
mean pressure of only 267 lbs. upon a piston of prof)ortionate area, 
one-fifth of a second after explosion. For further details of these 
interesting experiments, the student is referred to Mr. Clerk's 
excellent book Tlie Gas Engine^ pp. 95 to 104. 

Wall Action in Gkts Engine Cylinders. — All these researches 
tend to show that the causes of loss of heat, and consequent 
waste of heat energy, depend largely upon the total internal area 
of the cylinder exposed to the gaseous mixture. The less this 
area for a given cylinder volume, the higher will be the pressure. 
Therefore, the more the action of the walls can be diminished 
during the development of the heat, the more certain and rapid 
will be the explosion, and the greater the pressure of the gas. 
This result can be obtained in three ways, by reducing — 

1. The time during which the wall action continues. 

2. Its intensity. 

3. The proportion of area of the walls to the volume of the 
gases. 

1. Opinions vary greatly as to the advantage of high piston 
speeds in gas engines, but the tendency of modern engineers is, 
in the main, to increase speed within reasonable limits. Beyond 
about 300 revolutions per minute, M. Richard considers that 
the friction and heat developed are too great to work 9,n engine 
continuously, and if much heat is generated by explosion, a 
correspondingly large amount is discharged at exhaust. Within 
certain limits, however, high speeds are advantageous, because 
the colder walls have less time to act upon the hotter gases, 
and carry off their heat. The same arguments show the value 
of ignition at the dead point. The piston having reached the 
end of its return stroke, and exhausted some of its energy of 
motion, does not move at the required velocity until driven out 
again. Explosion being practically completed before the volume 
of the cylinder is enlarged by the out stroke of the piston, the 
cooler walls have not much time to diminish the high temperature 
of the gases produced by explosion, and reduce the pressure 
before it can act on the piston. The rapid expansion so much 
insisted on by Professor Witz has the same effect, in diminishing 
the wall action. The more rapidly the walls are uncovered, the 
less time is allowed them to act on the gases, and carry off the 
heat. At the same time rapid and complete expansion does not 
always mean a ]iroportionate utilisation of the heat supplied to the 
engine. M. Richard shows by the figures given in the Society 
of Arts' Trials that in the Atkinson engine, where expansion is 
greater in proportion to admission and compi-ession, the heat 
carried off by the walls, that is, during the expansion stroke, is 
relatively small, but more is discharged into the exhaust than in 
engines having a less expansion. If the two items of heat 
expenditure be added together (see table, p. 242), they will be 



EXPLOSION AND COMBUSTION IN A OAS ENGINE. 253 

found almost the same as in the Otto engine tested at the same 
time. 

2. To diminish this great action of the walls, and to equalise 
their temperature and that of the gases, it is necessary to raise 
the temperature of the one, or lower that of the other. To raise 
the temperature of the walls is impossible, without injury to the 
engine. But by diluting the charge of gas with air to the limit 
of inflammability, and by utilising the inert gases, the heat of 
explosion may be diminished, without affecting the efficiency of 
the engine. This diminution of the maximum temperature is 
the reason of the comparatively high efficiency obtained in 
practice, with engines having combustion at constant pressure. 
As there is no very sudden rise in temperature, less heat is carried 
off by the walls, and more remains to do work on tlie piston. 

3. The third is perhaps the greatest source of waste of heat in 
the engine cylinder. The most effectual method of diminishing 
the wall action is by previous compression of the charge. In 
M. Richard's opinion it is only by this means that the losses of 
heat can be sensibly reduced, because compression diminishes 
the volume of the gases exposed to the cooling influences of the 
walls. Other conditions being equal, the larger the cylinder, the 
smaller will be the loss to the walls, because the smaller their 
area relative to the volume of the gases. As a result, less heat 
will be lost per cubic foot of gas to the walls and water jacket. 

Iioss of Heat. — But however carefully an engine may be 
designed, to keep the temperature and pressure of the charge 
within practical limits, all authorities are agreed that the greater 
part of the heat in a gas motor is lost by radiation and conduc- 
tion, or discharged at exhaust. These are the two great sources 
of waste. If the heat accounts of the four engines given at 
p. 242 be compared, it will be seen that the jacket water and the 
exhaust carried off between them from 65 to 75 per cent, of 
the total heat developed. In the opinion of so competent an 
authority as M. Richard this waste cannot, in our present state 
of knowledge, be avoided. The heat economised from the one is 
usually wasted to the other. If the losses from the walls be 
diminished, the heat of the exhaust gases is increased. Nor is 
it passible at present to prevent the loss to the jacket to any 
great extent. 

Notwithstanding every effort to determine the right mixture 
of gas and air, and to obtain complete combustion, as far as 
possible, the actual pressure in a gas engine is seldom more than 
Hbout half the calculated. As pressure is always in strict pro- 
portion to heat, this deficiency, shown by the indicator diagrams, 
proves that much of the heat contained in the chemical consti- 
tuents of the gas, and which ought to be liberated by their com- 
bination with oxygen during combustion, is either carried off, or 
not evolved. If all the heat were developed at the moment of 



254 GAS BNGINES. 

explosion, and expended in doing work on the piston, the cnrye 
representing the expansion of the gases would be adiabatia The 
line of expansion would follow the theoretical line of Camot's 
cycle, and exhibit heat neither added nor abstracted, but solely 
employed in doing work. That this does not take place in prac- 
tice can be seen, by comparing theoretical with actual diagrams. 
The difference between them is considerable. The line indicating 
the decrease in temperatures consequent on expansion is much 
higher in the theoretical than in the actual diagrams. 

Variations in Expansion Curve. — The Otto diagram at p. 
237 shows a peculiarity in the pressures obtained in the cylinder 
of later compression engines, which has not hitherto been satis- 
factorily explained. The fall of the expansion curve in the 
theoretical is, as we have said, more rapid than in an actual 
diagram. This theoretical curve represents exactly the fall in 
pressure, and therefore in temperature, which would be obtained, 
if the gases expended their heat entirely in doing work. If the 
curve of the actual diagram is flatter, and does not fall so rapidly, 
this difference shows that the pressure does not in practice sink 
so quickly, and heat is not parted with as speedily as in theory. 
The law of the mechanical equivalent proves that the amount of 
heat expended in doing work does not vary, but is always the 
same, in practice as in theory. If, therefore, the pressure and 
temperature do not fall so rapidly in an actual engine, heat is 
added io some way. This addition of heat is obtained either 
from within or from without. Most authorities maintain that 
it is evolved from the mixture itself, because the walls of the 
cylinder, cooled by the water jacket, must always be at a lower 
temperature thitn the gases they enclose, and cannot convey heat 
to them. In considering the difference between inflammation 
and combustion, it has been shown that the moment of maximum 
explosion or pressure does not always agree with that of complete 
combustion. The two operations are not simultaneous. The 
gases may reach their maximum pressure, and the particles be 
driven widely apart by the flame spreading through them, before 
their perfect combination with the oxygen of the air, and recon- 
stitution as CO2 (carbonic acid) and HjO (water vapour). This 
is the phenomenon which is now acknowledged by most scientific 
men to take place in the cylinder of a gas engine, and to cause the 
addition of heat shown in the slow fall of the expansion curve. 
The gases continue to re-combine and evolve heat after the period 
of maximum inflammation and pressure, and while the piston has 
already begun to move out by the force of the explosion. This 
chemical action is faithfully reproduced in the indicator diagram. 

Equilibrium of Heat. — It is generally admitted that, in the 
cylinders of almost all direct-acting engines, with explosion at 
constant volume, this '* equilibrium of heat,'' as it has been called, 
takes place. Heat is suppressed at the maximum temperature 



EXPLOSION AND COMBUSTION IN A GAS ENGINE. 255 

of explosion, to be evolved aflorwards, during the expansion 
stroke. In many gas engines the expansion curve falls rather 
more rapidly than in the Otto diagram at p. 237. Even then, 
however, so much heat is carried off by the walls, that there 
could be no approximation to adiabatic expansion, unless heat 
were in some way added, to counteract the wall cooling effect. 
The phenomenon is described in German by the expressive term 
"nachbrennen.". In English it is called "slow combustion," 
but it would be more correct to term it "after combustion." 
The fact is now well established, but the causes of this "after 
combustion " of the gases are still uncertain, and the following 
theories have been advanced to account for it 

Stratifloatioii. — The first was put forward by Otto, because 
it was in the diagrams of his engines that the effect of this 
" after combustion" upon the expansion curve was first studied 
He claimed it as a direct result of the stratification of the 
charge, one of the improvements specified in his patent of 1876. 
Instead of admitting the gas and air together through valves, as 
in later engines, the admission ports of the Otto were so arranged, 
that the air entered first. The gas valve then slowly opened, 
and the air was diluted with gas, the mixture increasing in 
percentage of gas as it continued to enter the cylinder until, the 
air port closing, nothing but gas was finally admitted. The pro- 
ducts of combustion were not expelled from the cylinder, but 
remained and combined with the air in front of the fresh charge, 
to form a sort of cushion between the richer mixture and the 
piston, and to deaden the shock of the explosion. Thus between 
the piston and the ignition port there were — 1, Products of 
combustion. 2, Pure air. 3, Air diluted with gas. 4, Gas 
only. According to Otto, combustion is very rapid at first 
through the explosive charge nearest the admission port. It 
spreads more slowly through the poorer mixture, because of its 
gi'eater dilution with air, and with the products of the former 
charge (which MM. Berthelot and Vieille's experiments have 
proved to retard combustion), and hence the whole heat is not 
developed at once. Not only did Otto recognise the existence 
of the phenomenon of " after combustion," but he endeavoured 
to utilise it. In his opinion, this chemical burning process was 
under control, and might be produced at will, and turned to 
advantage by stratification of the charge. 

This theory was supported by experiments made on an engine 
at the Otto Deutzer Gas-Fabrik. A glass chamber or pi*o- 
longation was added to the cylinder of the engine at the 
admission end, and cigarette smoke was introduced into it by 
the momentary opening of a cock, when the piston was at the 
inner dead point The movement of the smoke could be watched 
through the glass. Instead of passing through the cylinder and 
impinging against the piston, it remained near the admission 



256 OAS ENGINES. 

cock, and only the back part of the cylinder was filled with it, 
even after the crank had made several revolutions. Some how- 
ever were not convinced by this experiment that the admission 
of the mixture into the cylinder could be regulated at will, and 
other trials were made on a 4 H.P. engine by Professors Schottler, 
Teichmann, and Lewicki, to determine whether sti*atification of 
the charge actually existed or not. In these, admission was 
effected as usual through an ordinary slide valve. Ignition 
took place at the back of the cylinder, but there was also a 
special arrangement, by means of which the charge could be 
ignited at the side only, behind the piston, and in front of the 
compression space. As long as the ordinary ignition at the 
further end was used, indicator diagrams were obtained, similar 
to the one at p. 237. But when the mixture was ignited at the 
side, the brake horse-power, representing the work actually done 
by the engine, sank to half the normal power, and the diagrams 
showed a great diminution in the pressure, and retardation in 
the time of maximum explosion. The ignitions obtained were 
uncertain, often failed entirely, and were always too late. 
Analyses of the gases, taken from different parts of the cylinder, 
were also made by Professors Dewar and Teichmann, and it 
was found, as might have been expected, that their chemical 
composition in the lighting port, at the end furthest from the 
piston, was much richer than in front of the compression space. 
With a strong mixture, Teichmann found that the charge con- 
tained 16*2 per cent, of rich gas in the igniting port, 13*3 per 
cent, in the centre of the compression space, and 9*1 per cent, 
close to the piston. 

The theory that stratification of the charge, which these ex- 
periments were undertaken to prove, caused the effects of after 
combustion has now been abandoned. Professor Schottler and 
other scientific observers have pointed out that smoke cannot be 
considered as fairly representing the gaseous charge in the 
cylinder of an engine. Nor does it always remain at the back 
of the cylinder ; in experiments undertaken by him on a 
Koerting engine, the whole cylinder was filled with a cloud of 
smoke. That ignition at the side proves stratification of the 
charge has also been disputed. It shows that the mixture is 
richer in some parts than in others, which might naturally be 
inferred under any conditions, but not that the gas remains in 
layers after introduction, although such a dispoRition is im- 
parted to it at first. In experiments made on a Benz engine, 
under the same working conditions as the Otto, this partial 
stratification was not found to exist, and the charge was ignited 
with equal certainty at various parts of the cylinder. The 
latest authorities on the subject maintain that stratification 
cannot be preserved, even if the gases enter the cylinder in 
successive layers of richness, because of the compressive and 



DISSOCIATIOK IN A GAS ENGINE. 257 

mixing power exerted by the back stroke of the piston. It is 
impossible, they say, to conceive that the charge can adhere to 
the original order of its admission, when the rapidity with 
which the piston compresses it is considered, and even if strati- 
fication were proved, it is not sufficient to explain "after 
combustion." 

M. Richard is, however, of opinion that there is an evident 
gain in efficiency if the products of combustion remain in the 
cylinder, although the actual stratification is not preserved. In 
the first place, to retain the burnt gases does not weaken the 
succeeding explosion if care be taken, as in the Otto engine, that 
the richest part of the mixture lies round the ignition port. 
Without any attempt at regular stratification, the products of 
combustion will naturally be disposed round the piston, and act 
as a cushion to deaden the shock of explosion. Again, these 
inert gases are at a high temperature, and if they be left in the 
cylinder, instead of being carried off to the exhaust, more heat 
remains to increase the pressure and expansion, and less is dis- 
charged. 

DiBSOCiation. — The next theory to account for the phenomenon 
of " after combustion " has been advanced by Mr. Dugald Clerk. 
He attributes it to the chemical action known as " dissociation." 
At certain high temperatures chemical compounds decompose, 
or separate into their constituent elements, and do not recombine 
until the temperature has fallen. Thus heat, which is one of the 
great forces in combining chemical elements, is also a powerful 
agency in splitting up compounds. The existence of this pheno- 
menon has been repeatedly verified. Without it, it would be 
possible, during the combustion of gases, to reach much higher 
temperatures than have ever been attained in practice. If, for 
instance, steam be raised to a very high temperature, it ceases 
to be steam, and decomposes into its elements of oxygen and 
hydrogen. The higher the temperature, the more complete the 
dissociation, until a point is reached, above which all gases exist 
only as primary elements. The temperatures of compound gases, 
therefore, are probably limited, though the extent of this limita- 
tion has not yet been determined. Without dissociation it 
should be possible in theory to raise the temperature of hydro- 
gen burning in oxygen to 9000** 0., but no experiments have, to 
the author's knowledge, been made, in which a temperature of 
3800** C. has been exceeded. Clerk maintains that, at the tem- 
peratures produced in a gas engine dissociation takes place, and 
checks the further development of heat. The gases decompose, 
their heat is suppressed, and not evolved until, the temperature 
being lowered by expansion, the chemical elements are able to 
recombine. If dissociation existed in the cylinder of a gas 
engine, its action would be as described by Mr. Clerk. Most 
scientific men, however, are now agreed that the estimate of 

17 



258 QAS ENGINES. 

temperature on which the theory is based is incorrect. Mr. 
Clerk, following Deville, is of opinion that dissociation com- 
mences at a temperature of from 1,000* C. to 1,200" C. Since the 
results of his researches were published, it has been proved by 
the experiments of Mallard and Le Chatelier and others, that 
dissociation takes place at much higher temperatures than those 
in a gas engine cylinder. For carbonic acid it is perceptible at 
IjSOO'* C. and is Jess than 5 per cent, at 2,000°, but with steam, dis- 
sociation only appears at a temperature above 2,500** C. and at 
3,300" C. it is still very slight. The liighest temperature in a gas 
engine is probably never above 1,870" 0. Abs. It is impossible, 
therefore, to account for the phenomenon of " after comljustion " 
by the theory of dissociation. 

Cooling Action of Walls. — Professor Witz has advanced 
another theory to explain it, and supports his view with the 
weight of his scientific reputation and experience. He attributes 
the variation of temperature shown in the slow fall of the 
expansion curve, and the suppression and retarded evolution of 
heat, entirely to the cooling action of the cylinder walls. To this 
he refers all the phenomena hitherto obscure in the cylinder of 
a gas engine. He is of opinion that this cooling effect has been 
neglected hitherto, and that, next to the charge itself, the walls 
play the most important part in the cycle of an engine. By 
carrying off the heat generated at the moment of explosion, 
they instantly diminish the temperature. Although continu- 
ally cooled by the jacket, they act as reservoirs, and actually 
restore to the gas, during the latter part of the stroke, some of 
the heat they had previously absorbed.* In the earlier gas 
engines, without compression or ignition at the dead point, and 
with a much smaller range of temperature, the effect of the 
walls, though ignored, was very great. In modern engines this 
effect is greatly restricted, with the result, according to Witz, 
that the walls are able to refund heat to the gas during the 
expansion stroke. 

Professor Schottler agrees with Witz as to the marked effect 
produced by the walls. He is of opinion that the phenomenon 
of " nachbrennen " may be in part attributed to heat actually 
restored by the walls, and specially by the piston, to the hot 
gases. He suggests that the heat evolved by the combination 
of the chemical elements is transmitted, at the moment of its 
development, through the walls to the water, and that there is 
a fraction of a second during combustion when the temperature 
of the walls is actually higher than that of the gases they enclose. 
The effect would be the continued development of heat along 
the expansion line, after the attainment of maximum pressure. 

•The opinions of Professor Witz here given touch, in the author's 
opinion, upon debateable ground. 



WALL ACTION IN A GAS ENGINE. 

Inorease of Speoiflo Heats. — A fourth solution of th& 
problem has been suggested by MM. Mallard and Le Ch atelier. 
From various experiments they have made, they are of opinion 
that the specific heats of gases increase at very high temperatures, 
and that this increase may in part account for "after com- 
bustion." The subject is still in the stage of investigation, and 
no very positive determinations have, we believe, yet been made. 

Whatever the causes producing the phenomenon of "nach 
brennen," there can be no doubt that it is in itself injurious, and 
not, as Otto considered, advantageous. The suppressed heat, 
although ultimately developed, is not evolved at the right time, 
and therefore cannot contribute to the maximum pressure of 
explosion. In practice and in theory the full utilisation of the 
heat supplied to an engine depends on the range — that is, the 
maximum temperature of explosion, and the minimum temper- 
ature of exhaust. Whatever checks the attainment of this 
maximum temperature has an injurious effect on the efficiency 
of the engine. The difficulties of the subject have been ably 
summed up by M. Richard in the following words : — 

Cylinder Wall Action. — "No satisfactory answer has yet 
been found to the question: What is the cause of the loss of heat 
during explosion and expansion ? It cannot be denied that it 
is partly caused by the action of the walls ; they have an in- 
fluence which, if studied alone, may almost be formulated as a law. 
But is the effect of the walls varying or constant? To what 
extent does it intervene, during the motor stroke, in the other 
phenomena? These are, — the increase of specific heat at the 
temperature of explosion (not yet universally admitted); — 
dissociation, a phenomenon rather suspected than proved ; — 
combustion continuing during expansion, which some deny and 
others vehemently affirm. If it exists, as in my opinion it does, 
it is a result of the composition of the charge, compression, and 
the method of ignition. In a word, it is a most complex ])henO' 
menon, not only in itself, but l)ecause it is connected with all the 
actions simultaneously produced during the short period of a 
motor stroke. . . . The experimental theory of the gas 
engine has not yet been made. . . . Like that of the steam 
engine it cannot be determined without experiments, but it is of 
such importance that it ought to be undertaken, without shrink- 
ing from the toil and difficulty, the length and cost of the study 
it involves." 

The Author is of opinion that the cylinder wall action in gas^ 
as in steam engines, is very considerable, and it may be well to 
compare this action in the two types of motors. In the case of a 
single-acting horizontal four-cycle gas engine with water jacket, 
the difference of temperature between the gas and the metal is 
greater than between the steam and the metal in a steam engine. 
In gas engines heat goes through the metal walls nearly always 



^60 GAS ENGINES. 

in one direction, from the centre of the cylinder outwards. There 
is a greater flow of heat at the explosion end of the cylinder and 
in the large clearance areas, because the temperature and pressure 
are greater than at the other non-explosion end. During the three 
non-motor strokes, the heat would travel through the walls much 
less rapidly, and the temperature of the metal would tend to 
become uniform. In a steam engine the wall action fluctuates 
periodically in the thickness of the metal, first in one direction, 
then in the other. During the steam stroke, heat passes from the 
hot steam to the cooler walls, and during the exhaust, from the 
hotter walls in the reverse direction. 

In a gas engine, during the explosion and expansion stroke, 
the heat passes rapidly doubtless from the hot gases to the cooler 
walls, which, on the side touched by the water, are at a tempera- 
ture of say about 150° to 180** F. The temperature of the gases 
will vary from say 1,800** to 2,500® F. If we assume an average of 
2,000° F., there will be a difference of temperature of about 
2,000' - 150' = 1,850" F. between the gases and the metal 
next the water, causing the heat to flow through the walls to 
the cooler circulating water. 

During the exhaust stroke the gases are still much hotter than 
the walls, and the heat flow will be in the same direction, but 
less energetic. During the admission stroke of cold gas and air, 
the movement of heat will either be reversed or nearly suspended, 
as, by the time the charge has actually filled the hot cylinder 
and clearance, there will no doubt be little difference in tem- 
perature between it and the walls. During the compression 
stroke, there will be a tendency for the heat to pass again to the 
walls from tlie gases. We may thus assume that the flow of 
heat, though varying much in intensity, is generally from the 
internal to the external surfaces of the cast-iron walls, or from 
the hot gases to the cooler water. 

At the explosion end of the cylinder the clearance surfaces 
will, to the thickness perhaps of a sheet of paper, approximate to 
the temperature of the dry gases. The lubricating oil will act 
as a non-conducting film, and tend to check the flow of heat. Nor 
must it be forgotten that, according to the opinion of the best 
authorities, the centre of the charge is much hotter than the 
parts in contact with the walls. The flow of heat may, there- 
fore, commence from a hot nucleus in the middle of the cylinder. 
The thickness of the metal walls will vary say in different 
sized engine cylinders, from 1 to 1^ inch. As the metal at the 
explosion end will be much hotter than at the other end, there 
will probably be a flow of heat horizontally through the thickness 
of the wall towards the crank, as well as the flow radially from 
the hot gases. These two movements of heat will probably form 
a thermal gradient slightly inclined to the axis of the cylinder. 

Effect of Time. — Again, there is the question of time influ- 



WALL ACTION IN A OAS ENGINE. 261 

encing the \vall heat action. Taking two motors running at 
different revolutions per minute, the engine with the slower 
piston speed will give the water and the gases more time to 
interchange their heat than the quicker running engine, in 
which a shorter time per stroke is allowed. The quantity of 
jacket water passing per minute round the cylinder, to cool so 
many square feet of internal surface, is another factor of this 
complicated wall action. In other words, the number of lbs. of 
water ])assing per minute through the jacket per square foot of 
internal surface should always be considered, as well as the action 
of the metal of the piston. As the clearance area exposed to the 
hot gases is much larger in gas than in steam engines, these 
important surfaces should, in accurate experiments, be given in 
square feet, as well as the cylinder volume. During the different 
strokes violent movements will take place inside the cylinder, 
particularly during the explosion stroke, when the whole cylinder 
is probably filled with flame. 

M. Richard maintains rightly that experiments are much 
needed to determine the temperature of gas engine walls, of 
which so little is known. The author hopes soon to be able to 
make some tests similar to those he has undertaken upon steam 
engine walls, where the temperature of the cast-iron cylinder 
plays a most important part. 

Professor Kennedy shares the opinions of most other scientific 
men as to the great future possibilities of the gas engine. In 
a lecture delivered at the Royal Institution (in April, 1893), on 
the " Utilisation of Energy," he places the theoretical efficiency 
of coal gas at 80 per cent. Of this a gas engine, he says, utilisea 
from 22 to 32 per cent. The waste of heat is chiefly due to the 
jacket, because, owing to the high temperature of the working 
agent, we have, in Professor Kennedy's words, to "adopt the 
somewhat barbarous expedient of continually keeping the metal 
cool by means of a water jacket." 



PAKT 11. 
PETROLEUM ENGINES. 



CHAPTER I. 

THE DISCOVERY, UTILISATION, AND 
PROPERTIES OF OIL. 

Contents. — Petroleum ; Its Production in Russia, America, and Scotland 
— Composition — Distillation — Density — Flashing Point— Evaporation 
— Pressure— Utilisation of Oil — As Liquid Fuel on Railways, ic.-— Oil 
Gas — Mansfield Producer — Keith — Rogers —Pintsch. 

The name petroloum, or rock oil, is derived from the Latin 
words petrUy a rock, and oleiun, oil. It is a mineral product, 
obtained from the earth in two difierent ways. Most of the oil 
used is drawn, at varying depths, from subterranean wells in a 
natural state, but a relatively small quantity is also produced by 
distillation from bituminous shale. The extraction of oil has 
been carried on in Scotland since 1850 ; the discovery of rock 
oil in the earth, and the operations necessary for bringing it to 
the surface, date from a few years later. A third kind of oil, 
which must be distinguished from these, is obtained from fat 
and grease, by the application of intense heat, in retorts. The 
process is usually continued until the oil has been converted 
into a rich gas. Lastly, there are vegetable oils, such as linseed, 
castor, palm, or olive oil, from which gas may also be produced 
by distillation. To distil gas from any kind of oil, great heat is 
necessary. 

Petroleum. — Within the last few years petroleum has become 
a most important article of commerce. There are two countries 
from which this oil has been chiefly obtained, the shores of the 
Caspian Sea, and the centre of the United States. It is known, 
however, to exist in many other places, and has been found in 
South America, especially in Peru and the Argentine Republic, 
India, Assam (1890), Beloochistan, Japan, China, Burmah, 
Egypt, Australia, and in the south-east of Europe. Some 
scientific men are of opinion that petroleum may be discovered 
valmost everywhere, if the borings are carried deep enough into the 



264 PETROLEUM ENGINES. 

earth. But for the present the supply from Kussia is, and will 
probably long continue to be, practically unlimited, and Russian 
petroleum is conveyed so cheaply all over Europe, that it is not 
worth while to seek for oil elsewhere. The chief centre of the oil 
industry is round the shores of the Caspian, though important 
oil fields have been discovered in Central Asia. It is only within 
the last twenty years that these vast natural reservoirs have 
been utilised, and their discovery threatens in several ways to 
revolutionise commerce, especially as providing a new kind of 
fuel. The town of £aku, the capital of the Caspian district, has 
from a village become a large and flourishing city, since oil has 
been found in great quantity in its vicinity. The existence of 
an oil region round the Caspian was known from the earliest 
times. The district was called by the ancients the Fire Region, 
and the mysterious flames which issued from fissures in the 
rocks were worshipped by them 600 years b.c., as manifestations 
of the Fire God. These flames are nothing more than the gases 
given off* by the subterranean oil reservoirs, ignited at some 
remote period, and which have never been extinguislied. 

Russian Oil. — The extraction of oil from the earth in the 
Baku district is now carried out on a regular system. The wells 
are tapped, or the oil is " struck," as it is called, and immedi- 
ately rises to the surface at a high pressure. It is then conveyed 
through pipes direct to the refineries, where it is purified, and 
separated into the lighter volatile oils, as naphtha, the lighting 
or intermediate oils, lubricating oils, which are all of varying 
density, and the crude petroleum called "astatki." Through 
another line of pipes it is next carried to fill the tanks in the 
steamers on the Caspian, no other method of distribution being 
employed. This system of pipes forms a network over an area 
of several square miles round Baku, and the oil issues from the 
wells at so high a pressure that no pumping is required, until 
the flow has begun to diminish. It is struck at a depth varying 
from 70 to 825 feet below the surface. A new line of pipes is 
now in course of construction, for carrying refined oil from Baku 
through the Caucasus to Batoum, on the Black Sea, 560 miles 
distant, from whence it will be easy to convey it by sea to the 
south of Russia, and throughout the countries bordering on the 
Mediterranean. The oil industry of Baku has been greatly 
developed, and almost created by two Swedish engineers, Robert 
and Ludwig Nobel, who have organised a system of obtaining 
and refining the oil, and distributing it all over Europe (see 
Note on p. 334.) 

American Oil. — The second source of oil supply is from 
Pennsylvania and the Alleghany district in North America, and 
the newly discovered oil regions of Athabasca in Central Canada. 
Here also the supply is ample, though the borings are carried 
much lower, oil being usually found at a depth of from 500 to 



DIFFERENT OILS. 2G5 

4,000 feet from the surface. The petroleum wells of Pennsyl- 
vania were discovered about 1859. The oil issues from the 
ground at a lower pressure than in the Caspian district, and is 
pumped through pipes, often hundreds of miles in length, to the 
chief commercial centres of the United States. There are about 
25,000 petroleum wells in America, and 400 in the Casiuan, but 
the supply in the latter is very much more abundant. In 1890 
the yield of oil from the American wells was 2.600,000 gallons a 
day, and from the Caspian nearly 2,700,000 gallons per day. 
The supply from both is at present apparently unlimited, and 
there are only two drawbacks to the use of petroleum all over 
the world, for lighting and heating purposes, &c. The first is 
the cost and difficulty of transport, which will no doubt be over- 
come ; the second is the varying composition and inflammable 
nature of the oil, necessitating great care in carrying and storing 
it. 

Scotch Oil. — The third source from whence mineral oil is 
obtained is by distillation from bituminous shale or "petroleum 
peat/' Dr. James Young was the first to discover, in 1850, 
that petroleum could be extracted from shale, rich beds of which 
exist in abundance in Scotland. The oil produced is usually 
known as paraffin oil. 

Thus during the last forty years a vast and hitherto unsus- 
pected store of natural fuel has been brought to light, which, 
unlike coal, requires no laborious mining process to extract it 
from the earth. It is merely necessary to bore a well of the 
requisite depth, with an instrument known as a well-driller, 
over which a wooden structure is erected, and the oil issues 
forth in a liquid stream. The boring is often now carried out 
by a motor driven by oil. Care must be taken, however, in the 
Caspian district, that the flow of* oil is not allowed to become so 
great as to flood the country. Thus in the Droojba fountain, in 
1883, the oil rose to a height of 300 feet, and flowed at the rate of 
2,000,000 gallons a day. It burst to the surface with the force 
of a miniature volcano, carrying with it large quantities of sand, 
and the damage done to the surrounding country ruined the 
owners. About £10,000 worth of oil per day were thrown up, 
and most of it wasted. To check this tremendous flow, the wells 
are now ** capped " at once if possible, and frequently covered 
over, or " corked," if the price of oil is at the time so low as to 
render the working unrenumerative. Thus the supply is stored 
for future use. 

Composition of Oil. — The difficulties of utilising Nature's 
bountiful stores of light and heat become apparent, as soon as 
the chemical constituents of the oil are examined. The composi- 
tion of fuel such as coal, wood, ifec, varies considerably, and 
with oil it is even less uniform. Crude petroleum consists of 
various hydrocarbons, diflering in their proportions in every oil. 



266 PETROLEUM ENGINES. 

and all are of different densities. The density of some is very 
low, and they are much lighter than water, taken as unity. 
The lighter the more dangerous the oil, because the more 
rapidly it evaporates, giving off inflammable vapours which 
ignite if a light be brought near. As the chemical constituents 
of petroleum have different boiling points, they are vaporised 
at different temperatures. Hence the difficulty of dealing with 
these oils. At a low temperature the lightest and most volatile 
hydrocarbons rise to the surface, and are first given off. As the 
temperature increases, and more heat is applied, the heavier and 
more inflammable vapours are separated, till at last all the 
volatile oil is evaporated, and a thick heavy liquid is left, called 
**astatki" in Russia, and "residuum" in America. Formerly 
this petroleum refuse was considered useless, and thrown aWay. 
Both in America and Russia it was allowed at times to run to 
waste, and formed lakes of liquid petroleum, w^hich were often 
set on tire, to got rid of tliem, or carried off by pipes into the 
sea. It is now known that, though this refuse cannot be 
volatilised by the application of heat, however intense, it may 
be broken up or divided into spray and utilised, by injecting air 
or steam into it, and thus burning it. It is used extensively in 
Russia and America, and forms a valuable liquid fuel, though it 
does not yet pay for the cost of trans])ort to other countries. 

Distillation. — If American, Russian, or Scotch shale oil be 
heated gradually in a retort, it is divided up by what is called 
''fractional distillation" as follows: — The highly inflammable 
vapours, variously known as naphtha, gazolene, benzoline, 
petroleum essence, petroleum spirit, tkc, are first given off. 
These vapours, though very dangerous, are free from impurity. 
As the temperature of the retort increases heavier gases are 
liberated, and carbon is deposited ; while at a red heat the 
residuum is split up, or "cracked," and converted into a true oil 
gas, containing a large amount of tarry products. " Cracking " 
is the term apjdied to petroleum when, by subjecting it to great 
heat, the heavier chemical constituents, which will not them- 
selves vaporise at that temperature, are split up and decomposed 
into lighter hydrocarbons, which are readily evaporated. The 
different oils thus formed are, in the order of their density, 
volatile essence or spirit ; kerosene or illuminating oil ; what is 
called intermediate oil, because in density and inflammability it 
is between the light and heavy oils ; thick lubricating oil ; and 
lastly, astatki or refuse, which may either be made into gas, or by 
the addition of superheated steam, burnt as fuel. 

Different Densities of Oil. — It must not be supposes! that 
these different classes of oil are ever rigidly defined in any 
petroleum. They pass one into the other, from lighter to 
Jieavier, by imperceptible gradations, and can only be correctly 
tabulated according to their density. Nor is even this an 



PROPERTIES OF OIL. 267 

infallible test of their quality, for the same oil, naphtha, kerosene, 
or lubricating oil, will often vary in density, according to the 
petroleum from which it is obtained. Sometimes an oil will 
contain more of the lighter, sometimes more of the heavier 
constituents. At Baku the lightest oils are found in wells of 
great depth, and hence the high pressure of the oil fountains, and 
the force with which they rise ; the heavier kinds lie nearer the 
surface. The difficulty caused by the varying density of 
petroleum, and the different temperatures at which it vaporises, 
is the main obstacle to its use in heat engines, and special means 
are employed in every case to convert it into spray. If the oil 
be simply injected into the cylinder like gas, the hydrocarbons 
are soon deposited, and are troublesome to get rid of. If only 
the lightest oils or spirit are used, they are even more easily 
ignited than gas, but they are expensive, and dangerous to 
transport. Legally they can only be used with special precau- 
tions in heat motors. The heavy liquid refuse is not inflammay)le, 
and therefore quite safe, but to employ it in an engine it must 
be previously distilled in a retort. It is the intermediate kinds 
of oil, obtained from heavy residuum after refining away the 
volatile essence, which are chiefly used for lighting and heating ; 
and petroleum, as distinguished from spirit or naphtha, motors, 
are usually driven by these oils only. If natural oils have 
been carefully refined, and their more volatile constituents drawn 
off by the ai)plication of heat, they become much less inflam- 
mable. Lighting oil or common kerosene will not ignite at the 
ordinary temperature, and will even extinguish a lighted taper 
'when applied to it. S[)ecial legjd restrictions are, however, 
placed on the use of oil iu most European countries, and a test, 
known as the Flashing Point, is prescribed, to determine its 
inflammability. 

Flashing Point. — The flashing point of an oil is the tempera- 
ture at which it gives off inflammable vapours, and depends on 
its density or specific gravity — that is, the ratio of a given 
volume ot its weight, as com[)ared to the ^veight of the same 
volume of water, at the ordinary temperature of GO'* F. Careful 
allowance must always be made for temperature in dealing with 
oil, because petroleum increases greatly in volume with every 
degree rise of heat. To determine its specific gravity, water is 
taken as unity, and the weights of oil as fractions. The higher 
the specific gravity of oil, or the more closely it apj)roximates to 
the density of water, the less danger will there be of its inflam- 
mability. Petroleum which has a low specific gravity contains 
very light chemical constituents, and these are given off at a low 
temperature. Hence it catches fire more readily than other oils 
of greater density, containing heavier hydrocarbons. 

The flashing point of oil is usually determined by means of 
an apparatus designed by Sir F. Abel. A small cylindrical 



268 



PETROLEUM ENGINES. 



vessel of oil is immersed in another containing water. The tight 
fitting cover of the small oil vessel has three holes, which are 
opened by moving a slide. Through one a thermometer is passed 
info the vessel, and a gas burner and flame are fixed above the 
others. The oil is heated by raising the temperature of the 
water in the receiver by means of a lamp. At about 66" F., or 
19° C, the slide in the cover of the air vessel is slowly with- 
drawn, the flame tilted till it is brought beneath the lid through 
the holes, and the oil watched until it lights or flashes. The 
flashing point is determined from the number of degrees rise in 
temperature of the oil. In most countries of Europe and 
America no oil may be used giving oft' intiammable vapours, 
that is having a flashing point below a certain limit of tempera- 
ture, which is fixed by law. Jn England and Canada the limit 
is 7^3"* F., or 22** C. ; in America and Austria, 37-5* C; in 
France, 35'' C: Russia, 28' C; Germany, 21" C. The flashing 
point may also be roughly determined by holding a lighted taper 
above an open vessel filled with oil. As the temperature is 
raised by the heat of the taper, light hydrocarbons are liberated, 
rise to the surface and ignite, and if a thermometer be placed 
in the oil, the flashing point can be read off*. The higher this 
limit of ignition, the safer the oil. 

Ignition Point. — The ignition or burning point of oil is the 
temperature at which the oil itself, and not the inflammable 

Table of Constituents of Petroleum— Specific Gravity 
AND Flashing Point [Rohinaon), 



American Oil. 


1 

Russian Oil. t Scotch Shale Oil. 

.1 




Coustitucnts. ! 


1 


' 


FlMshing 


1 
Volume. 


Sperific 
Gravitj. 


Yoliime. 

1 


Specific v«inm« ' Specific 
(iravity. >^"'««ne- Gravity. 

1 


r»»iiit. 




Percent. 




1 
Percent. 


, Percent. 


Decrees C. 


Benzine light oils, 


J 4 0-700 


10 


0-725 . 50 ; 0-730 


-10 


Benzine heavy oils. 


20 1 730 


3 


0-775 


... ... 





Kerosene lighting 








' 








oils, 


50 


0-810 


27 


0-822 1 


35 


0-805 


25 to 50 


Intermediate, . 


... 


... 


12 


OfcSS 


2 


0-850 


1U5 


Lubricating pyro- 


1 












naphtha oils, 


15 0S80 


32 


0-903! 


18 


0-885 


110to20O 


Paraffin wax (vase- 






1 






line), 


2 1 ... 


1 


925 12 


... 


... 


Residuumandloss,! 16 1 ... 

1 I 


24 


... 1 28 


... 





vapours given off*, takes fire. It is of course of greater import- 
ance to determine the flashing than the burning point, the former 
being reached long before the oil itself is raised to the ignition 
point. As the lowest legal flashing point of an oil is in England 
73"* F., naphtha or petroleum spirit, which ignites at a lower 



PROPERTIES OP OIL. 



269 



temperature and is very dangerous, may not be used. The 
flashing point of astatki or crude petroleum refuse is above 
200* C; intermediate Scotch shale oil has a flashing point of 
105'C. = 22rF. 

The table on p. 208 (from Professor Robinson's Gas and 
Petroleum Engines) gives the proportions, flashing point, and 
specific gravity of the different hydrocarbons contained in 
Russian, American, and Scotch petroleum. 

The next table shows the chemical constituents of the oils 
from the difierent countries and their heating value : — 



Chemical Composition and Heating Value of Different Oils 
{RohitMon), 



Country. 


DeKTlptlonofOil. 




1 1 


Mean Heat 

Value 
Per Lb. of 






Water = 1. 


C. 1 H. 1 0. 


Oil. 
B.T.U. 

^neat~ 








Per Per i Per 






cunt. cent. cent. 


L'uiu. 


BnasiaCBaku), 


Heavy crude petroleum, 


0-9.38 86-6 12-3 


1-1 


11,000 


f f 


Light crude petroleum, 


0-884 86-3 13-6 


01 


11,480 


f « 


Aatatki, 


184-6 13-9 


1-2 


10,340 


America, . 


Heavy crude petroleum, 


0-88C 84 9 13 7 


1-4 


10,680 


»> 


Common petroleum, 


88 3; 13-91 0-8 


10,102 


t« 


Astatki or residuum, 


928 87-111-7 1-2 


10,680 


Scotland, . 


Shale oil, 


0-860 86-5; 7-0 0-5 





Professor Bobinson's Experiments. — A series of careful 
and interesting experiments were undertaken by Professor 
Hobinson, to determine the nature of the changes produced by 
heat in different kinds of oil. In order to ascertain the pro- 
perties of oil, and how much additional heat was necessary to 
convert it into a vapour before using it in the cylinder of an 
engine, he desired to know the temperature at which the oil 
distilled or evaporated, and the pressure of the petroleum vapour 
given off. The first point could only be determined by the 
process of fractional distillation. A glass fiask filled with 
petroleum was placed in a sand bath, and slowly heated by the 
fiame of a Bunsen burner. Two thermometers were used, one 
in the oil, the other at the neck of the fiask. By this apparatus 
Professor Robinson was able to take the temperature of the oil, 
and of the vapour as it was given off; the latter was then 
passed through a glass tube surrounded with iced water into a 
graduated condenser. With water the boiling point would 
be always the same, but with oil it was necessary, as distillation 
ceased at one temperature, to increase it continually. The 
temperatures of the oil and vapour were found never to 
agree completely, but the higher the temperature of the 



270 PETROLEUM ENGINES. 

oil, the less difference there was between it and the tem- 
perature of the distilled vapour. A marked difference between 
the various oils tested was found, in the gradual or abrupt 
distillation of their constituents, and the percentage given 
off at the different temperatures. As a rule, Scotch shale oil 
distilled slowly at a high temperature, with the exception of 
Trinity or lighthouse oil, 55 per cent, of which distilled between. 
170° C. and 230° C. Some of the ordinary lubricating oils dis- 
tilled rapidly at a temperature commencing at 120'' C, the 
Russian at 130" C. The oils which distilled a large percentage 
of their volume within a limited range of temperature, showed a 
more or less uniform composition. Others evaporated slowly 
through a wide range, proving that they were more complex in 
composition, and made up of hydrocarbons having varying boil- 
ing points. Only a small i)ercentage of the heavy, intermediate, 
and Scotch shale oils was distilled at a very high temperature. 
The range of temperature aj)plied to these oils varied from 
120' C. to 270" C. At a temperature of from 215° C. to 240° C, 
about 50 per cent, of the American and Russian oils distilled. 

Evaporation of Oil. — The next experiments were undertaken 
to determine the evaporation from heavy oils in the open air, when 
exposed to a slow gentle heat, under ordinary atmospheric condi- 
tions, and thus the amount of light hydrocarbons they contained. 
Lighthouse, Scotch shale, and lubricating oils, having a specific 
gravity of 0-810 to 853, were tested. They were placed in shallow 
receivers, and a steady heat maintained beneath them, the tem- 
perature of the oils being kept for three hours at from 40" C. to 
1)5" C. The amount of evaporation was determined by weighing 
the oils before and after the experiments, and it was found that 
the percentage of loss varied inversely as their specific gravity. 
With the heaviest lubricating oil, the loss in weight was 2'9G per 
cent., with the lightest oil of 8 10 specific gravity it was 6*90 
per cent, in the same time. These experiments show the degrees 
of safety with which oils may be stored in hot climates, and the 
necessity of ventilating and keeping cool the oil tanks, thus 
diminishing risk and loss by evaporation. 

Pressures of Oil. — Professor Robinson next endeavoured 
to determine the pressures of the different oils, corresponding 
with a given rise in temperature. Some difliculty was experi- 
enced in making these trials, because it was found much less 
easy to prevent leakage from the joints with petroleum vapour, 
than with steam or lighting gas. The testing apparatus consisted 
of a U-shaped glass tube, having one limb longer than the other. 
At the end of the shorter was a spherical bulb, the longer was 
provided with a graduated scale. The tube and bulb were 
tilled with mercury and oil, the oil being up}>ermost in the bulb. 
The temperature was raised by placing the glass apparatus 
in a glycerine bath, gradually heated by a Bunsen burner. As 



PROFBUTIES OF OIL. 271 

tlie sample of oil in the bulb increased in temperature, the pres- 
sure generated by its vapour forced the mercury down the bulb 
and up the longer limb of the tube, and its rise was noted on the 
scale. Corrections were carefully made for the temperature of 
the room, latent heat of evaporation in the oil, expansion of the 
glass and mercury, &c. The height of the mercury in the tube 
showed the pressure attained by the peti'oleum vapour in the 
bulb, corresponding to the rise in temperature of the glycerine 
bath. The results of the experiments were afterwards plotted 
on curves, showing the proportional increase of pressure with 
increase of temperature, in the same way as with steam. Pro- 
fessor Robinson gives various curves exhibiting the temperatures 
and pressures for different oils. Jt was found that stenm had 
a higher pressure at a given temperature than any of the oils, 
except petroleum spirit or naphtha, the pressure of which rises 
more rapidly in proportion to its temperature. At 300'* F. the 
pressure of petroleum spirit was 125 lbs. and that of steam is 
55 lbs. per square inch. The pressure of ordinary oils was much 
less. Common lighting oils, chiefly American, gave an absolute 
pressure of a little above 150 centimetres of mercury, at temper- 
atures varying from 170" C. to 200** C, while the heavy oils, as 
Lighthouse or Scotch shale, having a specific gravity of about 
0'825, showed a very low absolute ])ressure,* 90 to 94 centi- 
metres of mercury at a temperature of 200^* C. The lighter the 
oil, the more nearly it approached the temperature and pressure 
of steam. At lower temperatures the oils exhibited great differ- 
ences of pressure, but at the lowest temperature tested, about 
80' C, all gave nearly the same pressure, viz., about 80 centi- 
metres of mercury (absolute pressure). At temperatures below 
100" C, the pressure of water vapour was very much higher than 
that of any oil. 

The pressure of air at a given temperature being known, it 
is possible, with the help of these valuable tables, to determine 
approximately the temperature and pressure of petroleum vapour, 
and therefore the work which should be obtained from a mixture 
of oil and air in the cylinder of an engine. ]Much, however, 
remains to be done, and at present we know little about 
the action of petroleum under great heat in a motor. The 
difficulties of the subject are increased by the complex constitu- 
tion of oil. The latent heat of evaporation of petroleum is 
about one-ninth that of water — that is, the same quantity of heat 
will evaporate nine times as much oil of average specific gravity 
as water, but the expansion of the vapour is only one-fifth that 
of water vapour or steam. Hence the same quantity of heat 
will produce ^ or 1*8 times as much oil vapour as steam from 
water (see p. 306). The above data are from Professor Bobin- 

* AbBolnte presrare Ib 14*7 lbs. below the presBure of the atmosphere. 



272 PETROLEUM ENGINES. 

son's able lectures at the Society of Arts on " The Uses of Petro- 
leum in Prime Motors," to which the student is referred for an 
exhaustive treatment of the subject. Professor Robinson has 
been the iirst, as far as the author is aware, to make a special 
study of this difficult question. 

Utilisation of Oil. — Having thus considered the chemical 
composition and properties of oil, it will be evident that though 
it can be utilised in many ways to produce heat, the process is 
complicated, because its constituents vary so widely. There 
are four methods by which petroleum may be used to generate 
mechanical energy in a heat motor. 

I. As liquid fuel it is burnt under a boiler to evaporate water. 
In this case the petroleum is simply used as fuel, and produces 
the same effect. It is injected through a nozzle, with a proper 
admixture of steam and air, into the furnace, where it is burnt 
in the ordinary way. The heaviest petroleum and oil refuse may 
be thus employed to generate heat; the greater the specific 
gravity of the oil, the better suited it is for fuel. 

II. Petroleum may be subjected to destructive distillation 
in a retort, and turned into a fixed gas, in the same way that 
lighting gas is distilled from coal. Any oil may be treated in 
this manner, but the best for distilling are the intermediate oils, 
which are neither so light that they escape before they can be 
gasified, nor so heavy that they cannot easily be broken up. 
The oil gas thus produced is exceedingly rich, having twice the 
heating value of coal gas. Mixed with air in proper proportions, 
this gas is introduced into the cylinder of an engine, and the force 
of the explosion drives the piston forward, as in a gas engine. 

III. The lighter and more volatile constituents of petroleum, 
such as gazolene, benzine, petroleum spirit, essence or naphtha, 
are used, in the same way as oil gas, to work a motor. The spirit 
is previously prepared, and the heavier hydrocarbons withdrawn. 
Except that the power necessary to drive the engine is obtained 
by explosion, the action of the volatile spirit is similar to that of 
steam in a steam engine, the spirit being condensed, re-evaporated, 
And used continuously, as in the Yarrow spirit launch. The same 
spirit is also used as a fuel to vaporise the working agent. 

IV. Ordinary petroleum is evaporated at a moderate temper- 
ature in an apparatus contiguous to the engine, and mixed 
with air is used, as in the spirit engine, to drive the piston by 
the force of explosion. Here also the oil constitutes both the 
fuel and the working agent. Engines employing this method 
to produce mechanical energy from petroleum may be divided 
roughly into two classes — (a) Those in which the whole of the 
crude petroleum is vaporised, and so broken up that practically 
no residuum is left ; (b) Those working with oils of lower specific 
gravity, in which cold air is charged with the volatile hydro- 
•carbons, and the heavy residuum wasted. Some of the latter may 



THE UTILISATION OP OIL AS FUEL. 273 

almost be called spirit engines, as the oil they retain for use is 
very light and inflammable. 

Various Methods. — All these methods of utilising petroleum 
as fuel present difficulties, owing to the complex nature of the 
oil, except when it is evaporated as a pure spirit. It was long 
thought impossible to burn the heavy astatki, but when con- 
verted into spray by injecting steam or air into it, it can under 
certain circumstances be profitably employed. When the petro- 
leum is turned into a fixed gas difficulties arise, because the oil 
gas becomes laden with tarry products which, unless it is well 
washed and cooled, clog the pipes and valves. There is another 
obstacle when the lighter constituents of petroleum are utilised 
in an engine. These are given off at different temperatures, and 
the process is assisted if a large surface of the oil is brought in 
contact with the air. It is therefore agitated mechanically, the 
whole of the volatile constituents are gradually evaporated, and 
a heavy residuum remains, which is usually wasted. Some 
inventors prefer thus to utilise only the lighter and more in- 
flammable portions of the oil, and to sacrifice the remainder, 
thereby obtaining much quicker evaporation, more power, and 
cleaner combustion than with heavier oils, though the consump- 
tion is greater. But the method more generally employed, as 
safer and less wasteful, is to evaporate the whole of the oil in 
the cylinder of an engine. This requires the application of ex- 
ternal heat. 

We will now consider — I. Petroleum as fuel, and II. Petro- 
leum when converted into oil gas. In the next chapter we shall 
treat of III. The use of Petroleum spirit, and IV. Crude petro- 
leum in oil engines. 

I. Petroleum as Fuel. — The advantages of petroleum, when 
burned as liquid fuel, are so great that it is safe to predict it 
will in time compete with coal and other fuels, and become an 
important factor in the commerce of the world. There are now 
on the Caspian forty " oil steamers," in which the boilers are fired 
with astatki. All the locomotives on the Tsaritzin and Grazi 
Railway in south-east Kussia are fitted with an apparatus for 
burning petroleum refuse, instead of coal, under their boilers. 
Coal in that part of Kussia being dear and scarce, the economy 
thus realised is considerable. In fact the Baku oil fields have 
created the Caspian fleet. The uses to which petroleum is now 
being turned in Russia, where the oil is obtained on the spot, 
will probably be extended to other parts of Eastern Europe, as 
soon as the pipe lines have been laid along the Caucasus to the 
Black Sea. 

Difl9.otilties. — The difficulties attached to the use of petroleum 
as fuel are — first, its complex constitution ; secondly, its inflam- 
mable nature ; and thirdly, its cost The two first do not apply to 
astatki or petroleum refuse. The heavy oil used on the Russian 

18 



274 PETROLEUM BNGIlTEfl. 

railways is scarcely more inflammable than coal, and there is con- 
sequently no danger in using it. This was proved during an 
accident on the line, when an engine and carriages left the rails, 
and the tank of astatki in the tender did not ignite. The constitu- 
tion of the petroleum is also fairly uniform, because all the volatile 
hydrocarbons have been evaporated, and though it is heavy and 
difficult to break up into spray, yet when combined with injec- 
tions of steam and air it forms a safe and excellent combustible. 
At present, however, it can only be used in countries producing 
it, on account of the cost of transport. In England it is not likely 
to compete with native coal, but it may in the future be found in 
our Colonies and Dependencies, and there be turned to great 
advantage for locomotive and marine engines. The steamships of 
the Chilian Company use 100,000 tons of petroleum yearly. An 
abundant supply is found in Peru, and oil fields are also being 
opened up in Ecuador. In Scotland we have an almost unlimited 
quantity of shale, capable of yielding 120 gallons of oil per ton, 
but it is chiefly utilised at present for making gas, and for 
metallurgical and other processes. The cost of petroleum 
delivered wholesale in London and Liverpool is — American 
Ordinary 3|d. to 4d. per gallon ; Russian Ordinary 3Jd. to 4d. 
per gallon ; Scotch Shale Oil 2Jd. per gallon. 

Advantages. — The first advantage of using petroleum as 
fuel, whether under boilers or in the cylinder of an engine, 
is its purity. It contains no sulphur, and is said to give oflT 
little or no smoke. If the oil is perfectly consumed, petroleum 
is the cleanest of all fuel. Another gain is that additional 
oiling is seldom required in the cylinder of engines driven by 
petroleum, because it acts as a lubricant. Where the oil is 
used as liquid fuel to evaporate water, heat is economised 
because, as it passes automatically into the furnace from a tank, 
it is not necesi-ary to open the tire door, and the temperature 
of the furnace is not lowered. Petroleum is also much more 
convenient to store, and occupies much less space than a cor- 
responding quantity of coal. Lastly it is of much greater 
heating value, as shown by the amount of water it evaporates 
per lb. of fuel. It has twice the evaporative power of some coal. 
Professor Robinson quotes figures to show that it evaporates at 
least 60 per cent, more steam than best Durham steam coal. 
Russian petroleum refuse burnt in a series of shallow troughs 
under ordinary boilers evaporated 14 J lbs. of water per lb. of 
refuse ; coal burnt in the same boiler gave an evaporation of 
7 to 8 lbs. water per lb. of coal. So high a result is not obtained 
when the astatki is sprayed. Professor XJnwin tested the 
evaporative value of petroleum under a steam boiler, and found 
it to be 1216 lbs. water (from and at 212' F.) per lb. of oil 
burned. The rate of evaporation was 075 lb. water per square 
foot of heating surface. He estimates the calorific value of the 



THE UTILISATION OF OIL AS FUEL. 275 

petroleum he used at about 25 per cent, higher than an equal 
weight of Welsh coal. 

Liquid Fuel. — lb is on the Russian South-Eastern Railway, 
between Grazi and Tsaritzin, that the value of petroleum as fuel 
for evaporating steam in locomotives has been thoroughly tested. 
Mr. Urquhart, the able superintendent of the line, has by 
degrees replaced coal by petroleum in almost all the engines 
under his charge. In the oil obtained at Baku there is a 
residuum of 70 to 75 per cent, after the volatile naphtha and 
ordinary kerosene have been drawn off by distillation, and 
prior to its utilisation under boilers on this railway enormous 
quantities of this refuse were thrown away. Before 1882 the 
locomotives were fired with anthracite, but after various attempts 
Mr. Urquhart succeeded in altering the shape of the fire box 
and tubes to burn petroleum. There are 423 miles of railway 
on the Grazi-Tsaritzin line, and 143 engines are now fired with 
petroleum. The specific gravity of the oil used varies from 
0'889 to 0-911, and its weight is 55 to 56 lbs. per cubic foot. 

The tank containing the petroleum is placed for safety inside 
the feed- water tank in the tender. The oil is drawn from the 
tank through a pipe, terminating in a nozzle, and injected into 
the furnace. The size of the orifice has been carefully determined 
by experiments. A smaller tube containing steam from the boiler 
passes down the centre of the oil pipe ; the steam and oil mingle 
at the mouth of the nozzle, and are injected as fine spray into the 
fire box. At the junction of the tube and fire box they are open 
to the atmosphere, and the air, having free access, is drawn by 
suction to the nozzle, and enters with the steam and oil. The 
force of the mingled blast is sufficient to break up the oil into 
very fine spray, which is driven against a fire brick division in 
tlie lower part of the fire box, and thus still further subdivided, 
before it rises into the upper part of the furnace as flame. A 
bridge of fire brick is now used to divide the fire box into two 
sections, and round and through this each jet of air, steam, and 
petroleum vapour has to pass. The actual arrangements of the 
fire box, «kc., vary of course with the class of boiler used, 
whether marine, horizontal, or vertical. Besides the locomotives, 
a great many stationary boilers are fired with petroleum. It 
was at first found difficult to keep the oil in a proper liquid 
state during the severe Russian winters. A certain quantity of 
solar oil (one of the lighter oils obtained from petroleum) is 
now added to it, and steam is carried from the locomotive boiler 
through the oil tank to heat it, by means of a coil of pipes. 

Cost of Working. — As regards the cost of working with 
petroleum, the best proof of its economy is the fact that from 
1882, when it was first used on this railway, to 1888, it gradually 
and entirely superseded coal. The saving in money is stated by 
Mr. Urquhart to be 43 per cent. In 1882 the consumption of coal 



276 PETBOLEUM ENGINES. 

per engine mile, including wood for lighting up, was 55-65 lbs., 
costing 7'64d. In 1887 30-72 lbs. of petroleum refuse were used 
per engine mile, costing 4 '43d. The expense of repairs was also 
much less, owing to the absence of sulphur in the oil. Other 
railways in Russia are now beginning to adopt petroleum as 
fuel. The locomotives on the new Trans-Caspian lines are fired 
with it, as no other combustible is available, and tlie stores of 
liquid fuel will probably form an important factor in the Kussian 
advance across Central Asia. 

On the question of the evaporative power and heating value 
of petroleum as compared with coal, Mr. Urquhart speaks with 
authority. He estimates the heating power of petroleum refuse 
at 19,832 B.T.U., and of an equal weight of good English coal at 
14,112 B.T.U. Theoretically, 1 lb. of petroleum refuse evapor- 
ates 17*1 lbs. of water at a pressure of 8 J atmospheres, while 1 
lb. of good English coal evaporates 12 lbs. water \mder the same 
conditions. In practice he found that the petroleum used on 
his engines evaporated, at this pressure, 14 lbs. water per lb., 
or 82 per cent, of the total possible evaporation. 

Petroleum on an English Railway.— Souie kinds of heavy 
petroleum are also utili.sed as fuel on the Great Eastern Railway. 
Mr. Holden, the locomotive superintendent, finding much diffi- 
culty in getting rid of the refuse from shale oil distilleries, tar 
from oil gas, green oil, creosote, and other heavy residuum, 
has adopted a method somewhat similar to the Russian plan, for 
burning them undor boilers instead of coal. The oil used is 
entirely heavy refuse, thicker and less easy to evaporate than 
Russian a.statki. It is conveyed from the tank through a pipe, 
and injected into a furnace, but the air passes to the spraying 
nozzle through a central pipe, and steam is twice sprayed on to 
the petroleum before it is sufficiently volatilised to be converted 
into fuel. In all cases where heavy oils are broken up by 
injection, superheated steam is found most eftectual. The injector 
is in three annular concentric parts. The liquid petroleum enters 
one passage, a jet of superheated steam pa.sses through another, 
carrying with it a current of air down the central tube. Before 
the oil reaches the nozzle, it is broken up into spray by the steam 
jet. After the petroleum, steam and air are sprayed into the 
fire box, a separate supply of superheated steam is injected into 
the petroleum, and completely atomises it. The vaporised 
liquid strikes against brickwork in the fire box, is broken up, 
and forms a broad, concentrated flame. On the bars of the grate 
a thin layer of fuel, usually cinders mixed with chalk, is kept 
burning, to maintain a uniformly high temperature, to decom- 
pose the oil, and ignite the spray. Arrangements are made to 
fire the boilers with oil or coal, according to the price at which 
they can be procured. It is sometimes cheaper to burn one, 
sometimes the other. As with the astatki burnt on the Russian 



THE UTILISATION OP OIL AS FUEL. 277 

railways, the oil is so thoroughly mixed with steam and air that 
there is no smoke, unless it is purposely produced by diminishing 
combustion. The mixture employed by Mr. Holden consists of 
two parts coal tar, and one part green oil, and costs generally 
about IJd. per gallon. The same system of firing locomotives 
with oil refuse is used on the Great Western Railway in the 
Argentine Republic, where there are abundant oil fields. 

Bailey-Friedrich Engine. — In this motor (which should bo 
carefully distinguished from the Bailey hot air engine), the 
arrangement for burning the oil to evaporate the water is some- 
what similar to that adopted in the locomotive engines driven by 
petroleum on the Russian railways. The double-acting vertical 
motor is a reproduction of the Friedrich steam engine with boiler 
and surface condenser, and can be fired either with coal or oil. 
When petroleum is used, it is drawn from a tank placed below 
the level of the boiler, injected into the fire box with a jet of 
steam to break it up into spray, and ignited as it reaches the 
grate. The flames heat the boiler tubes in the ordinary way. 
When starting the engine, before steam has been got up, the oil 
is injected with a stream of compressed air, obtained with a 
hand pump. The supply of steam to the jet of oil is regulated 
automatically through a diaphragm valve. Ordinary petroleum 
is used for this motor, and the consumption is said to be about 
.2 05 lbs. per I.H.P. per hour. The working cost depends of 
course upon the price of oil. 

Petroletun for Marine Purposes. — Marine boilers have often 
been fired by petroleum. About 1867 experiments were made 
by Mr. Isherwood, of the United States Navy, on board the 
gunboat "Pallas," on liquid petroleum as fuel. He was con- 
vinced of its superiority to coal in heating value, convenience 
of storage, weight, bulk, absence of stoking, and consequent 
saving of manual labour. He found also that the lighter oils, 
which explode very easily, burn completely, and leave no deposit. 
Against these advantages must be set the great drawback of 
using petroleum to any great extent as marine fuel, namely, the 
danger of carrying an iaflammable oil, giving off volatile gases 
at a low temperature, in bulk at sea. For this reason, no 
kinds of oil but heavy residuum and astatki are likely to be used 
at present for marine purposes, except on small ships. The oil 
tested by Isherwood was utilised in the same way as on the 
Russian and Great Eastern Railways — namely, injected into 
the furnaces, after being thoroughly mixed with steam and air. 
Petroleum refuse is as cheap in America as on the shores of the 
Caspian. 

11. Oil Gas. — The manufacture of gas from oil differs little in 
principle from the process of distilling gas from coal. The oil is 
dropped or poured into a retort kept at a strong heat, and the 
vapour given off is purified, washed, and cooled in the same way 



278 PETROLEUM ENGINES. 

as lighting gas. All oils are not equally fit for gas making. Very 
heavy oils, as tar or blast furnace oils, creosote, (be, though they 
are vaporised for a time by the application of heat, condense 
again under pressure, and cannot be converted into a fixed gas. 
The best way of utilising them is to burn them, as already 
described, under locomotive or other boilers. Oil of low specific 
gravity, as petroleum spirit, is too volatile and evaporates too 
readily. For making gas the best oils are the intermediate, such 
as Scotch shale oil, which are too heavy to be vaporised com- 
pletely in an oil engine, but are found to yield a very rich gas, 
well adapted for the purpose of driving motors. Vegetable oils 
and animal grease, fat or dripping can also be used in this way. 
Such motors, however, worked with oil gas in the same way as a 
gas engine is driven with lighting or cheap gas, are not oil engines, 
properly so-called, and must be distinguished from them. They 
do not, as in true oil engines, prepare the fuel for combustion, as 
well as utilise it in ignition and ex])losion. They are in reality 
gas engines, the gas used being distilled from oil instead of from 
coal. Nor is the economy so great as in oil motors, because heat 
must be applied, first to turn the oil into gas, and then to convert 
the gas into energy. In oil engines one application of heat 
suffices for both purposes, but the power generated is not so 
. great. 

Distillation of Oil Gkis — The method of distilling oil does 
not vary much in the different systems, though it is usually 
necessary to modify the process slightly, to suit the oil or other 
refuse utilised. Thus in Alsace and in parts of France where 
there are deposits of bituminous schist, the crude petroleum 
refuse is allowed to fall in a thin stream into the retort, which 
is kept at a dull red heat by means of a tire beneath, and after 
being purified the oil gas is stored ready for use. The gas 
obtained has twice the calorific value of the same volume of coal 
gas. In another process, where a wrought-iron retort is heated 
to a cherry red by a furnace, the gas distilled has four times the 
calorific value of coal gas, and costs about 60 centimes per cubic 
metre. The quality of the gas depends chiefly on the temperature 
of the retort. In other countries various substances are success- 
fully distilled to produce oil gas, such as linseed oil in Brazil, castor 
oil in Burmah, palm oil in West Africa, mutton fat in Australia 
And South America, and in general fatty refuse of all kinds, 
wherever it is found in abundance. In Great Britain oil gas is 
usually made from Scotch shale oil, of specific gravity 0*84 to 
0-87, flashing point'from 235° F. to 250^* F., and yielding about 
100 cubic feet of gas per gallon. The heating value of this inter- 
mediate oil is much increased, if the oil be injected into the retort 
by means of steam jets. The steam is decomposed by the heat ; 
00, a gas very rich in lighting value, is formed by the combina- 
tion of the oxygen in the steam and the carbon in the oil. 



THE UTILISATION OF OIL OAS. 



279 



And deposit of solid carbon is prevented. The following table 
gives the chemical analysis and heating value of oil gas, as 
manufactured by Messrs. Bogers of Watford : — 

Tablk 07 Composition and Heating Value or Oil Gas {Bobifuon). 





Volume of 
Ccinttltuent in 
1 Cubic Foot of 

OilOM. 


IT«at Valae per 
Cubic Foot of 
Conrtituent. 
Heat UniU. 


Heat Value of 

given amount 

of Constituent 

in a Cubic Foot 

of Oil Gas. 

Heat Unite 

(Ibe, X I'd 


Hydrogen, H, . . . 
Marsh gas, CH4, . 
Luminiferous hydro- 
carbons, C2H4, . 
Carbonic oxide, CO, 
Nitrogen, N, ... 
Oxygen, 0, . . . . 


0-3161 
0-4617 

0-1629 
00014 
0-0506 
00073 


191-13 
584-36 

93205 
190-02 


60-40 
269-80 

151-80 
0-27 


10000 


... 


482-27 ! 



The first oil gas producer was introduced into England in 1815 
by Mr. John Taylor, of Stratford, Essex. The oil was passed 
successively through two retorts, to vaporise it thoroughly. 
Experience has since shown that one retort, if kept steadily at a 
proper temperature, is sufficient to volatilise all the lighter hyxiro- 
carbons contained in the oil, and convert them into gas. 

Oil Gas Producers — Mansfield. — The Mansfield oil gas 
apparatus is one of the oldest producers, and that most com- 
monly used. Gas can be made in it, not only from petroleum, 
but from any kind of oil, fat, <fec. Fig. 104 gives an external 
elevation of this producer. A is the receptacle containing the 
oil or fat, which becomes gradually heated and liquefied, if solid, 
by the heat from the retort below. From here the oil passes in 
a thin continuous stream into the siphon pipe S, where it is 
vaporised, and conducted through the wide tube or hood, B, 
to the retort, R, in which it is further decomposed, and made 
into a permanent gas. The retort is placed in the centre of a 
cast-iron casing, C, lined with fire brick, L. Before any oil is 
admitted the brick lining is heated, and the retort brought to a 
cherry red heat, or a temperature of 1,600° to 1,800" F., by 
the fire F under the retort. Unless combustion is carefully 
adjusted by means of the damper D at the top of the furnace, 
regulating the discharge of the products of combustion, and the 
openings M below, admitting the cold air, the quality of the gas 
is affected. The cock through which the oil passes into the 
pipe S is not opened until the retort, as seen through the sight 
hole 77, has been heated to a cherry red. The gases from R pass 
through the hood B down the stand pipe P to the hydraulic 



280 



PETROLEUM ENGINES. 



box H, where they are washed, and freed from the tarry 
products given off in the manufacture of gas, by forcing them 
through water. The hood B rests upon two sockets. O, above 
the retort, is filled with lead, which melts with the heat, the hood 
sinks into it, and an impervious joint is thus formed during the 
gas making process. The other socket, K, is tilled with water 
to prevent the escape of gas unless there is any undue pressure, 
when it forces its way out. At V is another safety valve, in 




Fig. 104.— Mansfield Oil Gas Producer. 

case too much gas is produced ; the tarry deposits are with- 
drawn through the door N. The purified gases then pass 
through the pipe Q to a gasholder. 

Two things are necessary to make good gas in the Mansfield 
producer. The heat of the retort must be sufficiently perfect to 
decompose the oil, and the stream of oil must be so regulated 
that no more passes in at a time than will produce a rich gas. 
With intermediate oil, 1000 cubic feet of gas are made from 7 
to 9^ gallons of oil, or about 100 cubic feet per gallon. When 
iised to drive an Otto gas engine, Messrs. Crossley give the con- 
sumption in a 12 H.P. motor at 9 cubic feet of gas per I.H.P.,. 
or 10 cubic feet per B.H.P. per hour, the gas being more than 
twice as rich as lighting gas. The total cost of oil and fuel, 
with oil at 4 J d. per gallon, is about 6d. per 100 cubic feet. This 
is much more expensive than coal gas in England, but abroad^ 
where coal is usually dearer, power may sometimes be most 
cheaply obtained by an engine driven with gas made from oil or 



THE UTILISATION OF OIL GAS. 2SI 

fat in a Mansfield producer. At the Melbourne Exhibition in 
1888, an Otto engine was driven by gas thus generated from 
dripping or fat at the rate of 100 to 1 20 cubic feet per gallon. 
The flashing point of the fat was above 400' F., and it was 
previously liquefied by a burner. 

Keith. — The Keith oil gas producer is especially adapted for 
oil made from Scotch shale. The principle on which the gas is 
made is the same as in the Mansfield producer, but the process 
is more rapid. The oil filters down through shallow iron troughs 
placed in the retort, till it reaches the lowest pai't, where the 
temperature is highest. Here it is converted into a gas and led 
off to the washer, and then direct to the gasholder, where it is 
cooled and stored. The pipes are large, and the pressure of the 
gas is kept low until it has passed to the holder. As it is prin- 
cipally intended to drive engines, it is unnecessary to purify it 
further. For illuminating purposes it is again passed through 
lime and sawdust, and after it has reached the holder, the pres- 
sure is raised by compression pumps to 150 lbs. per square inch. 
The gas produced, of 60 candle power, is exceedingly rich, and 
too powerful to use in a gas engine without altering the valves 
and passages. It is therefore diluted with air in an apparatus 
called a mixer, in the proportion of 35 parts by volume of air to 
65 parts of oil gas, and is then of about the same strength as the 
lighting gas used in motors. It is, of course, again diluted with 
the proper proportion of air, when introduced into the cylinder 
of an engine. 

The most important application of the Keith oil gas process is 
on the Ailsa Crag lighthouse in Scotland. Here it supplies five 
8 H.P. Otto gas ens^ines, working the air compressors for the 
two fog signals. There are four air-pump cylinders, each 10 
inches diameter and 18-inch stroke ; they are driven at a speed 
of 160 revolutions, and the air is compressed to 75 lbs. per 
square inch. The fog signals are in different parts of the island, 
at a considerable distance from the air compressing station. To 
supply power for fog signals, which are often required at a few 
minutes* notice, gas engines are of special value, because they 
can be started without delay. In this lighthouse twelve gas 
retorts are used, producing 10,000 cubic feet in four hours from 
100 gallons of ordinary illuminating paraffin, distilled from Scotch 
shale. From 20 to 30 cwt. of coal are required to heat the retorts. 
The four engines consume 26 cubic feet of pure oil gas per H.P. 
per hour, or 6*5 cubic feet for each engine. The price of the gas. 
is 5s. 9d. per 1,000 cubic feet; total cost of working, about 1*1 6d. 
per effective H.P. per hour. The output is rather expensive, 
owing to the isolated position of the lighthouse, and cost of 
carriage of coal and oil. 

Bogere. — In the oil gas made by Messrs. Rogers, of Watford, 
steam heated by the waste heat from the furnace is injected with 



282 PETROLEUM ENGINES. 

the oil into the retorts. The steam is decomposed, and the 
oxygen contained in it combines with the carbon of the oil to 
form carbonic oxide, thus preventing the deposition of solid 
carbon to any considerable extent. Another producer has been 
designed by Mr. Thwaite, to utilise poorer oils than can be 
burnt in the cylinder of an oil engine. The system is somewhat 
similar to those already described, but the retort is placed in 
the centre of a slow combustion coke furnace. The oil trickles 
down the middle of the retort, and becomes completely gasified 
as it passes up the annular space at the side, which is heated by 
contact with the coke furnace. In all these processes, where 
the oil is first turned into gas, and then used to drive a motor, 
more power is developed than where it is evaporated directly in 
the cylinder, although some heat is lost. 

Pintsch. — The Pintsch oil gas system differs from those already 
described because the oil, being intended principally for illumi- 
nation, is more thoroughly purified. It is introduced successively 
into two retorts, one above the other. The upper, into which 
the oil first enters through an inverted siphon, is kept at a 
moderate temperature ; the lower retort, in which the process of 
evaporation is completed, is at a cherry red heat. As it enters, 
the oil is received on sheet-iron trays, over which it passes to 
the upper retort, and descends through pipes to the lower. It 
has now become a thick yellow vapour, in which shape it enters 
a hydraulic box, where it is partially washed, and thence passes 
to the condenser, the tar being carried off by overflow pipes to a 
separate tank. The gas is finally purified by forcing it through 
a vessel, the lower part of which is filled with water, and the 
upper with lime and sawdust. When cooled, it can be stored in 
the condenser at a pressure of about 10 atmospheres. The illu- 
minating power of the gas produced is about 40 or 50 candles, 
but the pressure causes it to lose 20 per cent, of its lighting 
power. The best and cheapest oil for the purpose is Scotch 
intermediate oil, having a specific gravity of about 0*840, and 
yielding between 80 and 90 cubic feet of gas per gallon of oil. 
The price of the gas varies according to the cost of the oil, 
fuel, (fee, from 5s. 6d. to 16s. per 1000 cubic feet. The carriages 
on the London Metropolitan and other railways have been for 
some years lighted with compressed Pintsch oil gas, at a cost of 
about 6s. to 7s. per 1000 cubic feet. It is also much used for 
lighting buoys at sea and in rivers, and is burnt in the floating 
lights on the Suez canal. 



VORKIKO METHOD IN OIL EN0IKE8. 283 



CHAPTER II. 

HISTORICAL— WORKING METHOD IN OIL ENGINES— 
CARBURETTED AIR. 

Contents. — Oil Motors — Carburators — Lothftmmer, Meyer, Schrab — 
Vaporisation of Oil — Oil Engines — Hock — Brayton — Spiel — Siemens. 

Oil Motors. — Having examined the first and second methods 
of applying oil to produce motive j>ower, and considered it I. as 
liquid fuel, and II. as a gas, we now come to the study of oil 
motors, properly so called. Even gas engines, though far more 
handy than steam, are not suitable for every purpose for which 
motive force is required. For small powers, where steam cannot 
be used, because of the complication of a boiler, nor gas, when 
there are no gasworks near, petroleum engines supply a want, and 
have undoubtedly a great future before them. It is a peculiarity of 
these motors that the fuel is delivered to them direct, so to speak, 
in its original condition. In a steam engine the water must first 
be evaporated over a furnace ; in a gas motor the working agent 
must either be distilled in a retort, or produced in a generator. 
The fuel for a petroleum engine may be purchased anywhere. No 
previous conversion into vapour is needed before it is delivered 
to the engine, and thus the cost of an additional gasifying or 
evaporating apparatus is saved. An oil engine is self-contained, 
and independent of any external adjunct, but to turn this advan- 
tage to account the difficulties of the constructor are somewhat 
increased. Not only must the engine be designed to utilise the 
working agent, and obtain mechanical energy from it, but the 
working agent must itself be produced, and the fuel prepared 
for combustion. This rather complicates the >^orking of the 
motor, since it must vaporise the oil, keep the quality of the 
spray produced uniform, and make it a proper medium for the 
heat imparted to it. 

There are two methods. Classes III. and IV. of the divisions 
in the preceding chapter, by which oil may, in the cylinder of an 
engine, be turned into a source of energy, viz. : — 

III. Light petroleum spirit, naphtha, benzoline, or carburetted 
air is exploded, and drives out the piston of an engine by the 
expansion of the gases. 

IV. Ordinary lighting or intermediate oil is also used to drive 
an engine by explosion and expansion, after its evaporation and 
conversion into petroleum spray. In Class III. atmospheric air 
at ordinary temperature and pressure is charged with volatile 



284 PETROLEUM ENGINES. 

spirit, in Class IV. the petroleum is pulverised and broken up 
into spray by a current of air, with the addition of heat. 

It must not be supposed, however, that all oil engines can be 
rigidly classed under either of these two divisions, because of the 
complex nature of petroleum, and the different temperatures at 
■which it evaporates. In one engine, the Yarrow spirit launch, 
nothing is used, with due precautions, but pure and rather dan- 
gerous petroleum spirit or ether. In a few motors, as the Priest- 
man and Trusty, the oil is so thoroughly pulverised and con- 
verted into spray (like the liquid fuel on the Kussian railways) 
that the whole is evaporated and no residuum left. There are 
also a laree number of oil engines, evaporating more or less of 
the volatile constituents of the petroleum, and with a propor- 
tionally large or small refuse, according to the amount of heat 
applied during the process, and the specific gravity of the oil 
used. 

There are two methods of evaporating petroleum, both used to 
prepare it for driving an engine — viz., hot and cold distillation. 
We have seen that, the less the specific gravity of the oil, the 
more volatile it is. The higher the temperature to which it is 
exposed, the greater the evaporation, or the amount of hydro- 
carbons given off. It is only the light and highly inflammable 
spirit used in engines of Class III. which can be evaporated from 
petroleum without the application of heat. The heavier oils, of 
greater specific gravity, must always be heated, not only to 
vaporise the larger portion of their constituents, but to counter- 
act the cold produced by evaporation. 

III. Distillation at ordinary atmospheric temperatures is pro- 
duced in the following way: — ^Atmos])heric air is passed over light 
hydrocarbon oil (refined petroleum), and a volatile spirit is given 
off in large quantities, impregnating the air in contact with it. 
This carburetted air is equal in lighting and heating properties to 
coal gas, and, mixed with a proper proportion of ordinary air, it is 
sufficiently inflammable to ignite, and to do work in the cylinder 
of an engine by the force of the explosion. Sometimes, instead 
of passing the air over a layer of the oil, a current is driven 
through substances impregnated with the volatile spirit. The 
specific gravity of this petroleum spirit varies from 0*650 to 
0*700, and its flashing point is generally so low that it cannot be 
used for commercial purposes. Motors in which it is employed 
ought scarcely to be called "oil engines." The working agent 
is simply inflammable petroleum essence, and is perhaps best dis- 
tinguished by the term usually applied to it abroad — "carbur- 
etted air." The ease with which this spirit can be obtained from 
ordinary petroleum by merely passing air over it shows that care 
is necessary. An inflammable vapour generated without the 
application of heat, will ignite at ordinary temperatures, and 
cannot safely be stored. Nearly all the early petroleum motors 



OIL ENQINE8 — CARBURATORS. 285 

employed this spirit as the motive power, and this is perhaps 
one reason why they did not come into general use. Owing to 
the inflammable nature of the working agent, a prejudice existed 
against them, which extended to all oil motors, and was not re- 
moved until the Priestman engine showed how ordinary oils 
could be utilised in the cylinder of a motor without danger. 

Engines driven with carburetted air are also open to two 
objections from an economic point of view. The continued 
evaporation of the more volatile portions of the petroleum leaves 
a heavy useless residuum, difficult to get rid of. As the spirit is 
given off, the cold produced by evaporation rapidly reduces the 
temperature of the oil, and renders it less ready to part with the 
lighter constituents. These essences also carry off with them 
mineral or organic substances, which when burnt in the cylinder 
leave a thick deposit, and clog the working ])arts. Explosive 
gases therefore, produced by passing cold air over petroleum oil, 
are not suitable for use in a gas engine. 

These difficulties are partly remedied by another method of 
obtaining carburetted air for a motor. The oil cistern or tank 
is placed near the cylinder, its temperature is thus raised, and 
the oil is agitated, in order to bring a larger surface in contact 
with the air. If the oil is slightly heated, not only will evapora- 
tion proceed more quickly, but less dangerous oil, having a 
greater specific gravity, can be used. The cost of working is also 
less, because volatile oils, having a specific gravity of about 0*650, 
are costly as well as dangerous. There is another advantage in 
placing the oil tank and carburating apparatus near the engine. 
Air which can be rapidly carburetted by bringing it in contact 
with petroleum essence, becomes decarburetted with equal facility, 
if exposed to a low temperature or pressure, or conveyed to the 
cylinder in long pipes. To carburate it therefore close to the 
engine economises the heat, and produces a more permanently 
infiammable gas. 

Carburators. — There are many devices for producing car- 
buretted air by passing it over petroleum spirit, but with most 
of them the gas obtained is only used for lighting. In America 
it is frequently made in the cellars of a house, as it is wanted 
for domestic purposes. The j>etroleum spirit or gasoline is 
stored in uuderground tanks, and air at ordinary temperature is 
pumped on to it through a pipe, and then drawn off and 
conveyed to the house burners. On this small scale there is 
little danger in employing carburetted air, but carburators above 
ground cannot be used with perfect safety. In most of them the 
principle is the same. Air is forced either by compression or 
suction through or over petroleum spirit, and becomes im- 
pregnated with the essence. In the Lothammer carburator air 
at ordinary temperature is pumped into an outer reservoir, 
containing an inner receiver partly filled with the carburating 



286 PBTBOLEUM ENGINES. 

liquid. It next passes at high pressure from the outer reservoir 
into tubes, which are carried down into the inner receiver below 
the level of the liquid. Here it is discharged through radiating 
horizontal pipes, and forced to pass upwards, the pressure of the 
air breaking up the liquid. By this process the air becomes 
thoroughly saturated with the volatile essence, and is then 
drawn off and stored. M. Lothammer claims to obtain a gas 
which does not lose its heating qualities, even when exposed to 
a teraporatiire of- 18" C. on leaving the carburator. Di-awings 
and a description of the Lothammer apparatus will be found in 
Ohauveau. 

In the Meyer curburator heat is employed to charge the air 
with petroleum essence. The oil or hydrocarbon liquid falls 
drop by drop into a small boiler, where it is evaporated by the 
heat from a burner below. The oil vapour at a high pressure 
next passes through an injector, where a proper proportion of 
air is drawn in witli it, and the two are thoroughly mixed before 
they enter the gas holder. Production is automatic, and the bell 
of the gasholder is made to regulate the admission of oil to the 
boiler, and the size of the flame. This method is said to produce 
carburetted air of nearly 10,000 calories per cubic metre heating 
value; it is principally used for driving engines. An ingenious 
method of carburating air, which does not yet seem to have been 
applied in practice, has been proposed by M. Schrab. Hydro- 
carbon liquid is substituted for water in the jacket of an engine 
cylinder, and is heated to about 80" C. by radiation from the 
walls. It then passes into a vaporising chamber, through which 
the exhaust gases are driven. The gases compressed into the 
boiling liquid become charged with hydrogen, carbonic oxide, and 
other combustible vaj>ours, and return to the cylinder, where 
they form the fresli charge, and are ignited and exf)anded as 
before. The inventor aflirms that these gases only require one- 
sixteenth as much petroleum essence to form an explosive 
mixture, as would be needed if fresh air were used, and that 
1 litre of gazolone per H.P. is sufficient to work his engine for 
10 hours. The idea has not apparently been further developed. 
There are numerous other carburators, especially in France, as 
the Mounier, Pieplu, <kc., but they are chiefly used to furnish 
carburetted air for illumination. Each oil motor employs a special 
type of carburator, or method of vaporising the oil, and these 
will be described later, in the account of the various engines. 

Utilisation of Oil. — Professor Unwin is of opinion that the 
three methods of utilising petroleum, as fuel under a boiler, as 
oil gas, and to carburate air, are none of them capable of any 
wide application, owing to the expense, the difficulties of trans- 
port, and the danger of using a highly inflammable liquid. The 
true oil engine of the future is probably of the fourth class, 
and comprises motors using and more or less completely eva- 



WORKING METHOD IN OIL ENGINES. 287 

porating ordinary lighting or heavy petroleum oils. Oil engines, 
however, are still in their infancy. If gas engines are younger 
and more modern than steam, and therefore liave more possi- 
bilities of future development, the same applies in a still greater 
degree to oil engines. In some respects a greater heat efficiency, 
both in theory and practice, ought to be obtained from oil than 
from gas motors. In the latter the pas must be kept cool till it 
is introduced into the cylinder, and therefore, as it has hitherto 
been found impossible to utilise the exhaust gases, a large propor- 
tion of the heat is wasted. In an oil engine the working agent 
should be at a high temperature from the first. A certain 
amount of heat is necessary to render the oil fit for evaporation, 
and this heat is usually supplied by making the exhaust gasea 
circulate round the oil tank or vaporiser. Hence more heat is 
utilised, the exhaust gases are comparatively cool at discharge, 
and a better working cycle should be the result. Hitherto,, 
however, in the few trials made on oil engines, the heat efficiency 
is found to be about the same as with gas engines. 

IV. In the fourth method of producing heat from oil — namely, 
by evaporating ordinary petroleum, and firing it as in a gas- 
engine — the density of the oil used varies from 0-800 to 0-840. 
To ignite so heavy a liquid, and utilise the force of the explo- 
sion to drive a piston, the oil must be broken up into spray, and 
converted at a high temperature into an inflammable vapour, 
before it is admitted to the cylinder. A blast of compressed air 
is generally forced into the petroleum, to divide it up ; the 
process is sometimes assisted by the injection of steam. All oil 
engines have a vaporiser or hot chamber, where the j)etroleum, 
either liquid or in the form of spray, is converted into 
vapour. The vaporiser is usually heated by a lamp at start- 
ing only, and afterwards by the exhaust gases. The air neces- 
sary for combustion is admitted and mixed with the charge of 
petroleum, after the latter has become vapour by the applica- 
tion of heat, air, and steam. The mixture is then drawn into 
the cylinder, as in a gas engine, by the suction of the piston. 
The process of ignition is rather delicate, because of the in- 
flammable nature of the oil. Sometimes a hot tube is used, but 
in general electric ignition is preferred. A gas engine employ- 
ing the latter method can easily be driven with petroleum by 
merely adding a carburator. A safety or non-return valve is 
also necessary, to prevent the flame from shooting back into the 
vaporiser. With these precautions ordinary lighting oil with 
a flashing point of from 25* C. to 50** C. may be used to generate 
mechanical power, as safely as gas or steam. It has not yet 
been adapted to any extent for marine purposes, except for 
small power launch engines, because the danger is great of 
storing quantities of inflammable liquid. In case of fire in a 
ship carrying light petroleum spirit, it would be impossible to 



288 PETROLEUM ENGINES. 

get rid of the fuel. The spirit being lighter than water, if sent 
overboard, would float on the surface of the water as a sheet of 
flame. The danger would be much less if heavy petroleum were 
used. 

Vaporisation of Oil. — There are three ways in which oil is 
treated, when employed as a combustible in the cylinder of an 
engine. In the first, it is broken up into spray, and thoroughly 
mixed with air, before it passes into the cylinder, as in the 
Priestman engine. In the second, liquid oil is injected into 
compressed and heated air, and instantly vaporised, as in the 
Hornsby-Akroyd engine. The third method is to admit the oil 
in small quantities into a vaporiser maintained at a very high 
temperature, which acts as a retort, and converts the oil into 
gas before it reaches the cylinder, as in the Trusty and Capitaine 
engines. One or other of these principles is followed in almost 
all oil motors, to render the petroleum fit for combustion, but a 
different arrangement is adopted in each particular engine, for 
the admission and vaporisation of the working agent or fuel. 

Oil Engines. — The earliest attempts to use petroleum to 
produce mecliauical energy were made soon after the introduc- 
tion of gjis engines. At that time, however, it was considered 
impossible to use ordinary petroleum, of about 0*800 specific 
gravity, because the difficulty of evaporating it was so great. 
To break it up into spray by a blast of air had not been pro- 
posed. Light petroleum spirit or inflammable ether was there- 
fore employed, and probably retarded the development of the 
oil engine. 

Hock. — About twenty years ago two engines appeared almost 
simultaneously, the Hock in Vienna, and the Bray ton in America. 
In the Hock engine, the patent for which was taken out in 1873, 
benzoline or volatile hydrocarbon gas was used, drawn from a 
reservoir at the back of the horizontal cylinder. The engine was 
of the two-cycle, single-acting, non-compressing type, with an 
explosion every revolution; the whole series of operations was 
carried out in one forward and return stroke. On one side of 
the cylinder was a small valve chest containing two valves, one 
for the admission of air, the other for the discharge of the exhaust 
gases, both worked by an eccentric from the main shaft. On the 
other side was the igniting apparatus. A little air pump, driven 
from the crank shaft, forced a current of air at each stroke into 
a small receiver filled with benzoline. The air became charged 
with benzoline, and a stream was directed through a nozzle against 
a permanent burner, placed close to an opening at the back of 
the cylinder. The benzoline ignited at the flame, a flap covering 
the admission valve was lifted by the suction of the in stroke, 
the flame drawn in, and the mixture in the cylinder ignited. 
The permanent burner was fed with petroleum spirit from tho 
same receiver. 



BRATTOl^ OIL ENGINE. 28^ 

The motor piston having passed the inner dead point, the 
suction of the out stroke drew a small quantity of hydrocarbon, 
at atmospheric pressure, from the reservoir at the back through 
a nozzle into the cylinder. At the same time a flap valve was 
lifted, and a stream of air, also at atmospheric pressure, was 
admitted through another nozzle beside it. The two nozzles 
being set slightly inclined to each other, the air pulverised the 
benzoline, and broke it up into spray. As the charge was too 
rich to use, it was next diluted with a second supply of air from 
the valve chest. When the piston had passed through about 
half the stroke, ignition took place as already described, the 
mixture being so arranged, that the richest portion lay nearest 
the ignition flame. The return stroke discharged the products 
of combustion. The centrifugal governor driven from the crank 
shaft acted by regulating the supply of air from the valve chest. 
If the speed was increased, the valve was held open longer, a 
larger quantity of air was admitted, and less benzoline. When 
the speed was reduced, and the balls of the governor fell, less air 
entered, the composition of the charge became richer, and the 
explosions more certain and stronger. This engine was popular 
for a time, but it was not permanently success&l, on account of 
the inflammable nature of the petroleum spirit used. Drawings 
are given in Schottler's book. 

Brayton. — The engine patented by Bray ton in 1872, and first 
constructed at Exeter, United States, was introduced into England 
about 1876. It was a better and more pi*actical motor than the 
Hock, because the oil used was of greater density, higher flashing 
point, and less inflammable. Brayton was the first to employ 
ordinary heavy petroleum and kerosene, boiling at about 150* C, 
in the cylinder of an engine, instead of light spirit or essence. 
His engine, called the " Ready Motor," was also the first, and 
till now the only engine of any note, to embody the principle of 
combustion at constant pressure, instead of at constant volume. 
It was originally worked with gas, and was first brought out in 
America ; the English patent was acquired by Messrs. Simon of 
Nottingham, who introduced it into this country in 1878 (see 
p. 51). A view of the Bray ton-Simon engine is given at Fig. 11. 
The charge of gas and air was ignited before its admission into 
the cylinder, entered in a state of flame, and drove the piston 
forward without any rise in pressure, a steady combustion being 
maintained behind it during one-third of the forward stroke. 
As Brayton found that the flame of the gas, in spite of the gauze 
diaphragm shutting it off from the pump cylinder, was apt to 
strike Imck, and ignite the compressed charge in it, he substi- 
tuted ordinary petroleum, instead of gas, as the motive power. 
The specific gravity of the oil used was 0*850, and one volume of 
petroleum was sufficient to carburate 21 volumes of air. 

The chief improvement exhibited by the Brayton engine over 

19 



290 PETROLEUM ENGINES. 

the Hock was that botli the air and the oil were admitted, at 
high pressure, into the motor cylinder from two pumps worked 
from the main and the auxiliary shafts. The pressure of the 
injection pulverised the petroleum, and the air became thoroughly 
impregnated. In all oil engines hitherto constructed, the use of 
light petroleum spirit made it unnecessary to spray the oil. The 
system of breaking it up by forcing a blast of air into it rendered 
possible the use of heavy petroleum oil. Bray ton was therefore 
the inventor of the first safe and practical oil engine, and in this 
respect his motor was the forerunner of the Priestman. Various 
modifications of it were brought out, some horizontal, others 
vertical, and one double-acting type is mentioned by Professor 
Witz. 

As shown at the Paris Exhibition of 1878, the Brayton engine 
was vertical and single acting, resembling the Simon at Fig. 11, 
p. 52, except that the crank and distributing shaft are above 
the cylinder. There is an impulse every revolution. The two 
pistons, motor and compressor, work downwards upon a beam 
joined to the motor crank by a connecting-rod. Both cylinders 
are of the same diameter, but the stroke of the compression pump 
is half that of the motor piston. From the pump, part of the 
compressed air is delivered direct through the carburator into the 
motor cylinder, and part is forced into a reservoir in the base. 
The air here stored is intended to equalise the pressure, and to 
assist in stai*ting the engine. On the other side of the motor 
cylinder is a small pump worked from an eccentric on the 
auxiliary shaft, to inject petroleum into the carburator. The 
different lift-vaJves to motor cylinder, pump and exhaust, are 
worked by cams from this auxiliary shaft, driven by bevel gear 
from the crank shaft, and revolving at the same speed. The 
admission cam to the working cylinder is moveable, and is shifted 
by the governor, in order to admit more or less of the charge, 
according to the speed of the engine. 

Carburator. — Fig. 105 gives a view of the carburator placed 
at the top, just above the motor cylinder. It is in three compart- 
ments. The carburation of the air takes place in the middle 
division B, which is filled with felt, sponge, or other porous 
substance, and is separated by a layer of perforated metal plates 
at P from the space below, 0, communicating through the opening 
D with the motor cylinder. The chamber C is always full of 
fiame. Petroleum is injected from the small oil pump through 
pipe £, and air from the pump through F into B. The jet of air 
pulverises the petroleum and breaks it up into spray, which 
thoroughly impregnates the porous material filling the chamber B. 
At this moment the valve V rises, and fresh air is drawn through 
the pipe O into the outer chamber A. In its onward passage 
through B, it carries with it a portion of the volatUised petroleum, 
and is ignited on reaching 0. From hence it passes forward into 



BRAYTON OIL ENGINE. 



291 



the cylinder in a sheet of flame. There is no explosion, the pres- 
sure of combustion of the charge being sufficient to drive out the 
piston. Thus, as in later oil engines, air is twice applied, first 
to break up the petroleum and convert it into spray, and then to 
dilute it in the same way as the charge in a gas engine. When 
the piston has passed through one-third of its stroke, the valve 
V closes, shutting off communication with the outer air, and the 
ignited vapour is expanded through the remaining two-thirds of 
the stroke. During the return the products of combustion are 
discharged . A s the dia- 
grams show , the pressure 
in the Bray ton engine is 
not high, and expansion 
is prolonged. Mean- 
while the two pumps 
have injected a fresh 
-charge of compressed 
air and petroleum into 
B, and by the time the 
piston has completed 
the in stroke, and before 
the valve V rises, the 
porous material filling 
the chamber is saturated 
with pulverised petro- 
leum, ready to be carried 
into the cylinder at the 
next admission of air. 
To start the engine, 
petroleum is pumped 
in by hand, and com- 
pressed air admitted 
from the reservoir, and 
when the carburator is full of oil vapour, the little plug at G 
is withdrawn, and a lighted match applied; the mixture ignites, 
and the piston begins to work. 

The Brayton engine is constructed on the same principle as the 
Davy safety lamp, namely, that of preventing back ignition by 
the use of a wire gauze, or perforated metal plates. It was found 
that, when heavy petroleum was used, the fiame did not shoot 
back, though with compressed gas, accidents were of frequent 
occurrence. Combustion in the chamber C is maintained con- 
stant by the compressed air injected at F, and the engine is said 
to work with extreme regularity. The change introduced by 
Brayton seems to show that ordinary petroleum is, under certain 
•circumstances, not so inflammable as lighting gas, but as used by 
him it had one great disadvantage. The petroleum vapour 
•deposited much carbon and soot in the passages, ports, <fec., and 







Fig. 105. — Brayton Carburator. 




PETROLEUM ENGINES. 

the eogine required frequent cleaning. Some of the deposit 
helped, it was said, to lubricate the engine. 

Trials. — A careful trial of a 5 H.P. American Brayton 
petroleum engine was made at Glasgow by Mr. Dugald Clerk in 
1878. The mean pressure was 30 2 lbs. per square inch, dia- 
meter of cylinder 8 inches, length of stroke 12 inches. The 
engine made 201 revolutions per minute, and the consumption 
of petroleum was 2*16 lbs, per I.H.P. per hour. Much of the 
total power developed was absorbed in driving the air and petro- 
leum pumpSi or in other words there was a good deal of friction. 
During the trial the engine indicated 9-5 H.P. in the motor 

cylinder. Of this the pump 
absorbed 4*1 H.P., there- 
fore the available H.P. was 
>4i2»o«. only 5-4. Only 6 per cent. 
Fig. 10e.-Brayton*8 Petroleum Engine ^^ ^^® total heat generated 
—Indicator Diagram. was utilised. The results 

show a much lower effi- 
ciency than might have been expected, owing to faulty con- 
struction. Fig. 106 gives a diagram taken from the motor 
cylinder during the trial, in which the prolonged expansion 
obtained with ignition at constant pressure is noticeable. 

SpieL — Both the two motors described above were brought 
out before the success of the Otto engine had fully established 
the superiority of the four-cycle type. In the next oil engine, 
patented by Spiel, and made in England by Messrs. Shirlaw & Co., 
Birmingham, the Beau de Bochas four-cycle is introduced, and the 
engine resembles the Otto in many respects. It has the drawback 
of using inflammable petroleum spirit of 0*700 or 0*730 specific 
gravity, instead of the safer heavy petroleum. Being easily 
volatilised, this spirit does not require so complicated a process 
to convert it into spray as in engines employing oil of greater 
density, and the method of introducing it in the Spiel is simple. 
The engine is horizontal and single-acting, standing on a solid 
base, with the reservoir of oil above. The organs of admission, 
distribution, and exhaust are worked from an auxiliary shafb, 
geared from the main shaft in the usual way. The exhaust is 
opened, as in the Otto, by a cam and levers from this shaft, and 
ignition is by a flame carried in a slide valve, working at the 
back of the cylinder ; the Spiel is probably the only oU engine 
firing the charge in this way. A portion of the compressed 
charge of oil and air in the cylinder passes through a grooved 
passage to a chamber in the slide valve which, as the slide is 
moved by a cam on the auxiliary shafb, is brought opposite a 
permanent flame in the valve cover, and fired. A spring eflects 
the return movement of the slide valve, when released by the 
cam, and the lighted mixture is brought in line with the cylinder 
port, when the remainder of the charge is fired The pressures 



SPIEL OIL EXOINE. 293 

of the charge in the cylinder, and of the flame in the ignition port 
are equalised, as in the Otto engine, by means of a small passage 
connecting them. 

The benzoline is drawn from the reservoir and injected into 
the cylinder by a small pump, the piston of which is worked 
by a cam, lever, and spring from the auxiliary shaft. The air- 
admission valve is also in connection with a crosshead attached 
to this pump. At the bottom of the pump is a double-seated 
horizontal lift valve, usually held open by a spring, in which 
position it communicates freely with the oil reservoir above. 
When the plunger pump is driven down, carrying with it the 
crosshead, the air valve is first lifted, and air enters a mixing 
chamber at the back of the cylinder. As the piston continues 
to descend, the horizontal valve is closed, and a passage opened 
from the pump into the mixing chamber. The pump sends a 
jet of petroleum spirit into the air, and in its passage it is 
broken into spray by striking against a projection. Thus the 
out (admission) stroke of the motor piston sucks into the cylin- 
der a stream of air mixed with petroleum spray. The engine 
has a ball governor which, if the speed be too great, interposes 
a small projection between the valve-rod of the pump and the 
levers working it. The two become locked and cannot move, 
and the valve remains open, admitting air only to the cylinder, 
until the projection falls back, and the speed is reduced. 

Drawings of this engine are given by Robinson and Schottler. 
Fig. 107 shows an indicator diagram of a Spiel oil engine when 
making 180 revolutions a minute. The consumption of oil, when 
this diagram was taken, was about 1 pint per B.H.R per hour. 
In another 14 B.H.P. 
Spiel engine having a 
cylinder diameter of 91 
inches, with 18 inches 
stroke, and making 160 
revolutions per minute. 

the consumption of — ^__ 

naphtha was 0-81 lb. per surttnn stroke. 

B.H.P. per hour,and the Fig. 107.— Smel Engine-Indicator 

cost of working 0'84d. Diagram, 

per B.H.P. per hour. 

The specific gravity of the oil used was about 0*725. It is con- 
tended by the English makers of the Spiel engine that, in spite 
of the difficulties of storing and transporting naphtha, owing to 
its inflammable nature, it is greatly superior to heavy oils for 
producing motive power. Some interesting experiments were 
made with a small model engine, running at over 500 revolutions 
per minute, in which the Beau de Rocbas cycle, comprising the 
operations of admission, compression, explosion plus expansion, 
and exhaust were carried out four times in a second. In another 




294 PETROLEUM ENGINES. 

experiment it was found possible, with an initial pressure of , 
over 300 lbs. per square inch, to remove the ignition flame, and 
obtain regular spontaneous combustion of the charge. Some 
hundreds of these engines are said to be at work. 

Siemens. — No account of internal combustion engines would 
be complete, without a mention of the motors designed and 
patented by Sir William Siemens. In 1860 he first devoted his 
attention to the subject, and from that time till 1881 he brought 
forward various engines, all intended to illustrate the principle 
of utilising the waste heat of the exhaust gases, by passing them 
through a regenerator before discharge. The incoming mix- 
ture entered the cylinder through the same regenerator. This 
idea of a regenerator in heat motors originated with Dr. Robert 
Stirling, a Scotch minister, in 1827, but it has hitherto been 
found impossible to apply it in practice, except in the case of hot 
air engines, though in metallurgy and other manufactures it is 
largely used. 

Sir William Siemens made many alterations and improvements 
in the heat engines he designed. In one he proposed to add a 
gas generator, producing water gas by the passage of steam and 
hot air under pressure through incandescent fuel. The gas 
thus made was pumped into a reservoir, and from thence into 
four cylinders, each serving to charge the next through a regen- 
erator formed of layers of metallic gauze. As the gas entered each 
cylinder it was ignited, and the burning gases expanded at con- 
stant pressure. This engine was not worked ; difficulties would 
doubtless have arisen in practice from the impossibility of pro-, 
ducing water gas continuously, and the inventor a^rwards 
turned his attention with more success to the generation of this 
gas for metallurgy. From 1846 to 1881 Sir W. Siemens took 
out a series of patents for internally fired engines. The last, 
shown at Fig. 108, designed not long before his death, exhibits 
his matured views on the subject. Strictly speaking, it is neither 
a gas nor an oil engine, but both combined, the gas used as the 
working agent being mixed with light petroleum spirit, to make 
it ignite more readily. The engine which, like the Bray ton, 
exhibits the principle of combustion at constant pressure, stands 
really in a separate class as a "regenerative" engine, and al- 
though never worked, it is valuable as indicating possibly on 
what lines the heat engine of the future may be improved. 

Siemens' Regenerative Engine. — Fipr. 108 shows a sectional 
elevation of the Siemens* Regenerative Engine. There are two 
motor cylinders, A and A^, working vertically through the con- 
necting-rods C and C^, upon the crank shaft K at an angle of 
180° apart. The pistons are solid, and lined on their upper face 
with fire-clay, to protect them from the heat. The cylinders are 
practically divided into two parts. The lower in each has a 
water cooling jacket, W, the upper part is lined with fire-clay, 



SIEMENS* REGENERATIVE ENGINE. 



295 



or other non-conducting material. The differential pistons com- 
press the mixture on one face during the down stroke, -while the 
explosive gases are expanded on the other. At the top of each 
cylinder are the regenerators R and Rp consisting of thin sheets 
of metallic gauze. All the valves for admission, distribution, 
and exhaust are contained in a revolving cylindrical valve F, 
worked from the crank shaft by equal bevel wheels G. The 
exhaust E is at the top, above the revolving valve, through 




Fig. 108. — Siemens' Regenerative Engine. 

which a passage at p^ is opened to it alternately from either 
cylinder. Gas and air, mixed in the ordinary proportions, are 
admitted through the pipes m and n, and ports p, opened by the 
rotatory movement of the valve, to the lower part of either 
cylinder, during one revolution of the cylindrical valve. The 
suction of the up stroke draws them in, the down stroke com- 
presses them into a reservoir at the side. From here the com- 
pressed mixture passes to the upper part of the cylinders, through 
the regenerator and the ports jOg. The products of combustion 
discharged on the upper face of the piston by the up stroke are 
forced through the regenerator on their way to the atmosphere, 



296 PETROLEUM ENGINES. 

ancl some of their surplus heat is stored up in it. As the fresh 
charge enters, drawn in by the vacuum produced by the expulsion 
of the exhaust gases, light hydrocarbon oil is dropped on to it 
from the oil tank O above. Part of the mixture of oil, lighting 
gas and air, heated already by contact with the regenerator, is 
fired by an electric spark within the cylinder, the dynamo of 
which is driven from the main shaft. The remainder of the charge 
is immediately kindled, and flows forward as flame into the 
cylinder, the flame being prevented from spreading back into 
the reservoir by the gauze diaphragm of the regenerator. The 
piston is driven down by the expansion of the gases, and com- 
presses below it a fresh charge into the reservoir ; during the 
up stroke the cylindrical valve opens communication with the 
exhaust. The differential pistons are deep, and the parts in 
contact with the cylinder walls touch only the cooler jacketed 
portion. 

Two ingenious and economical ideas are embodied in this 
engine. Some of the heat of combustion is stored in the re- 
generator, and imparted to the fresh charge, and inflammable oil 
is used to mix with the gas, and render it easier to ignite. 
Neither of these innovations has hitherto been applied to any 
extent in practice to gas or oil engines. This regenerative engine 
of 1881, however, may be considered as illustrating Sir William 
Siemens' latest ideas upon heat motors. It exhibits the outcome 
of the mature study of a man of scientific genius, and the direc- 
tion in which he thought the problem of heat engine efficiency 
should be solved. 



CHAPTER III. 



THE PRIESTMAN OIL ENGINE AND YARROW 
SPIRIT LAUNCH. 

Contents.— Requisites of Oil Engines — The Priestman — Spray Maker 
— Vaporiser — Governor — A pplications — Trials — Petroleum Spirit — 
Evaporative Power— Zephyr Spirit Launch. 

If Otto can claim the honour of having made the g€» engine a 
practical working success, after the efforts of Lenoir, Hugon, 
and others, the same credit belongs to Messrs. Priestman as 
regards oil engines. Long before the introduction of their 
motor into this country, oil engines had been designed and 
worked, but there was a prejudice against them, because of 
the inflammable petroleum spirit with which they were chiefly 
driven. The Brayton, the only engine using non-explosive petro- 



THE PBIBSTMAN OIL EKGINE. 297 

leum, had never become popular, owing probably to the imper- 
fections in its cycle, its extravagant consumption of oil, and low 
mechanical efficiency. Whatever the cause, oil engines were 
scarcely known or used until the appearance of the Priestman 
in 1888. About this time Messrs. Priestman acquired Et^ve's 
patent, and their oil motor was introduced at the Nottingham 
Agricultural Show in the same year. 

Requisites of Oil Engines. — In any engine intended to 
supply the deficiencies, and remedy the drawbacks of gas or 
steam, the following points must be considered. It should be — 
I. Self-contained and quite independent, having everything requi- 
site for its efficient working for a certain length of time. II. Safe 
and simple, using as the working agent a combustible which is 
neither difficult to procure, nor dangerous to transport. IIL 
Easy to handle, so that any ordinary unskilled workman can 
drive it. This is advisable, because these engines are frequently 
placed in the hands of labourers without any knowledge of 
machinery. lY. Compact, and easily transported from place to 
place. Y. Economical in working. 

These conditions are found in the Priestman engine, which is 
well adapted for all kinds of industrial operations requiring 
small powers. In many country places where gas cannot be 
procured, and abroad where coal is scarce and dear, it has pro- 
oably a great future before it, because it uses only common 
petroleum, which can be had everywhere. Coal is generally 
required in gas and steam engines, and in many countries it is 
obtained with difficulty. The store of petroleum is practically 
unlimited, and fresh sources are continually being opened up in 
different countries. 

Priestman. — This oil engine uses almost any kind of heavy 
petroleum, but it is not suitable for light volatile spirit. It 
works best with common petroleum, having a specific gravity 
of 0*800, and flashing point 100° F., but it may also be driven 
with heavy Scotch paraffin, of 0*820 specific gravity, and flashing 
point 150° F. Even common creosote of still lower density is 
available, but there are practical difficulties in the way of using 
it. Of course, the heavier the oil the thicker will be the 
residuum, and the more carbon is deposited inside the engine, 
the oftener it must be cleaned. Nor can these very heavy oils 
be properly treated in an engine cylinder, by raising the tem- 
perature. If the oil is too much heated, it is convei*ted into oil 
gas instead of vaporised spray, and tarry deposits accumulate 
in the working partn. The proper temperature of the charge of 
oil vapour and air on entering the cylinder has been determined 
by experiments at from 170° to 300' F., according to the size of 
engine. The proportions are 191 cubic feet of air to 015 cubic 
inch of oil vapour for a 1 H.P. engine. 

Fig. 109 gives an elevation, and Fig. 110 a sectional view of 



298 



PETROLEUM ENGINES. 




the cylinder, water jacket, and valves of the Priestman oil engine. 
Both drawings, as well as several of the following details, are 



THE PRIESTMAN OIL ENGINE. 



299 



taken from Professor Un"^in's paper in the Proceedings of the 
Institution of Civil Engineers, vol. cix., 1892. The horizontal 
motor cylinder, A, is divided from the compression space, C, the 
proportional volumes of the two being — clearance or compres- 
sion, 88 cubic inches ; volume described by the piston, 191 
cubic inches, for a 1 H.P. nominal engine. The piston P works 
on to the crank shaft K through a connecting-rod. At the 



Water 



IfUH Val^ 







Fig. 110.— Priestman Oil Engine. 

back of the cylinder are two valves, inlet and exhaust, as shown 
in the drawing, Fig. 110. The exhaust is worked by an eccentric, 
ky on the auxiliary shaft, R, Fig. 109, revolving at half the speed 
of the crank shaft, to which it is geared by wheels in the usual 
proportion. In the Priestman, as in most other oil engines, 
ordinary lift valves are used, of a simple type. Unless almost 
perfect combustion is obtained, there is much more deposit than 
in gas engines. The simpler the valves, the less liable they are 
to become clogged. 

Spray Maker. — The most important parts of the engine are 
the vaporiser and spray maker, shown below the cylinder 
(Fig. 109). The oil tank in Fig. 109 is under the crank shaft, 
and when full, is sufficient to last for two or three days. A glass 
gauge shows the level of oil. A small air pump, J, is worked by 
the eccentric A:, which also drives the exhaust valve. The air 
to supply this pump is filtered through gauze and cotton wool, 
and is then compressed into the oil tank at a pressure of 8 to 
15 lbs. per square inch above atmosphere. This pressure forces 
two streams of oil and air at a and b into the spray maker S, 
from whence they are injected into the vaporiser V. The oil 
is drawn from the bottom of the tank, the compressed air from 
the top, above the level of the oil, and both pass out through a 
six-way cock, r. When this cock is set upright, the supply of 
oil and air to the spray maker Ls cut off; when the cock is turned 



300 



PETROLEUM ENGINES. 




Fuf. 111.— Prieatman Oil 
Engine — Spray Maker. 



to the right they are admitted, and when set to the left they 
pass to a small lamp, L, below the vaporiser, used to heat it 
when starting the engine. 

The spray maker is one of the most ingenious parts of the 
motor. The oil and air from a and 6 are injected into the 
vaporiser through two concentric nozzles, as seen at Fig. 111. 
The pulverisation of the oil and its complete mixture with the 
air depend on the shape of the nozzles, 
and their exact form has only been deter- 
mined after numerous experiments by 
Messrs Priestman. Fig. Ill shows the 
latest type. The oil passes through the 
central tube in a small stream, and on 
being ejected from the mouth of the 
nozzle, spreads out in a fan shape. The 
annular air nozzle surrounds the central 
oil orifice, and the air is turned back 
with considerable force to meet the 
issuing oil at more than a right angle, 
the result being that both are violently 
driven out in a spray as fine as is re- 
quired. Fig. 112 shows the spray maker 
at its entry into the vaporiser, the method 
of regulating the supply by the governor, 
and of admitting the air necessary for the dilution of the charge. 
The oil and air from the spray maker enter at the pressure of the 
air pump. At the same time the in stroke of the motor piston 
lifts the non-return valve G, and draws into the vaporiser a 

supply of air from outside 
through the throttle valve 
F. This auxiliary charge 
enters round the oil and 
air admitted from the spray 
maker, and passes through 
a number of fine holes, d 
d, in the circular air pass- 
age of the vaporiser 6 6, 
and a filtering layer of 
cotton wool. The sudden 
inrush of fresh air sweeps 
forward the oil and air 
with it into the cylinder. 

Vaporiser. — The vapor- 
iser is divided into two 
parts. In the first the oil 
and compressed air are mixed with, and broken up by, the 
air admitted through F ; in the second the charge is com- 
pletely vaporised by the heat from the exhaust gases which 




Fig. 112.— Priestman Oil Engine — 
Vaporiser. 



THE PBIE8TMAN OIL ENGINE. 301 

at a temperature of about 600^ F., are led through pipe H, Fig. 
109, round the vaporising chamber, before being allowed to 
escape into the atmosphere. Thus there are two admissions of 
air — one to the spray maker under pressure from the oil tank, 
the second at atmospheric pressure to the vaporiser through F. 
In each case the oil is sprayed, and is thus twice pulverised 
before its actual vaporisation by heat begins. Unless the heat 
from the vaporiser were also applied to the oil spray, it would 
condense and separate from the air, before reaching the cylinder. 
The vaporiser is contained in the frame of the engine, under 
the cylinder, as seen at Fig. 109. 

Goyernor. — The speed of the engine is regulated by means of 
the spindle S above the throttle valve. It contains a small V- 
shaped opening at^ through which the oil is admitted from the 
tank to the spray maker, and the wing of the valve F is keyed 
to the lower part of the same spindle. The size of the sharp 
end of the Y, which is presented to the passage of the oil, can 
be exactly regulated to admit a given quantity. If the speed 
is too great, the centrifugal governor, which is connected to the 
spindle by levers, drives it down, and partly contracts the 
opening ^ admitting the oil from the tank. At the same time 
it acts upon the throttle valve, and reduces the quantity of outer 
air passing to the vaporiser. Thus the governor acts by dimin- 
ishing the strength of the explosions, not by cutting them out 
altogether, and the proportions of oil and air are always the 
same per stroke. As no explosions are ever missed, the engine 
works with great regularity. 

The charge, after being thus converted into spray and com- 
pletely volatilised, passes through the automatic admission valve 
n, Fig. 110, to the back of the cylinder. Here the usual series 
of operations carried out in internal combustion engines of the 
four-cycle type, takes place. The first out stroke draws in the 
air through the throttle valve F ; the charge is then mixed in 
the vaporiser, passes through into the cylinder, and the next 
back stroke compresses it into the space C. As the inner dead 
point is reached, the mixture is fired by the electric spark, the 
explosion drives out the piston, and during the next back stroke, 
the exhaust gases are discharged through the valve e, opened by 
the eccentric, into the jacket round the vaporiser, and thence to 
the atmosphere. 

Ignition. — The electric spark for firing the charge is generated 
in a battery shown to the left in Fig. 109. Many oil engines use 
this method of ignition, and its advantages over the hot tube 
are, in this class of motor, very great. The spark is more 
powerful, ignition more certain, and it is also safer, because 
there is no risk of previous explosion. Since there must always 
be a certain amount of inflammable oil vapour generated by the 
working heat of the engine, premature ignitions might occur 



302 PETROLEUM ENGINES. 

with other methods; with electricity there is no such danger. 
In the Priestman engine the electric spark is produced in the 
igniting plug t, inside the compression space, Fig. 110. Two 
platinum wires are conducted from the battery to this plug, 
where they are insulated in porcelain tubes; contact is estab- 
lished at the right moment by a projection on the eccentric rod, 
and an intermittent spark is produced. 

The shaft R driving eccentric k has three functions to perform. 
It causes the electric ignition of the charge; it works the valve 
e to open the exhaust, and it drives the small air pump J, through 
which the oil and air are sent from the tank to the spray maker. 
A small hand pump, seen in Fig. 109 at A, is used to pump air 
into the oil tank, before the engine is at work. To start, all 
that is necessary is to work the handle of the pump, and to turn 
the six- way cock, that a supply of oil from the tank may reach 
the lamp L below the vaporiser. When the lamp is lit, a few 
turns by hand are given to the flywheel, to draw a charge into 
the cylinder, the electric current is switched on, and the engine 
begins to work. The oil tank and vaporiser are easily accessible 
through the opening in the frame. 

Although the pressure with petroleum vapour rises more rapidly 
than with gas, the curve of pressures, shown by the indicator 
diagram of the Priestman engine, does not rise as high as in gas 
motors, owing partly to the larger compression space. One of the 
advantages of the engine is that it requires no lubrication. A 
small portion of the oil is condensed during the compression 
stroke, and deposited upon the inner surfaces of the cylinder. 
This oil is never burnt, but forms a layer of grease, and effectu- 
ally lubricates the engine, no other oiling in the cylinder being 
needed. As the fuel used is heavy mineral oil, it is not inflam- 
mable. Some interesting experiments to prove this have been 
made by Professor Robinson, who exhibited an engine before the 
Society of Arts in May, 1891, in which the air was shut off from 
the vaporiser, and oil injected alone. A lighted match held to 
this oil jet would not ignite, but it was readily fired as soon 
as the air was again admitted, to divide and break it up. 

Applications. — Although only brought out in 1888, the 
Priestman engine has already been applied to many purposes. 
The first portable oil engine of 6 H. P. was exhibited at the 
Jubilee Meeting of the Agricultural Society in 1889. In this 
and similar engines, the motor is made complete in itself by the 
addition of a tank, the water from which is circulated in the 
Kjylinder jacket by a pump, driven by an eccentric on the same 
shafb as the exhaust valve eccentric. As a portable locomotive 
engine to replace steam, the Priestman has already been found 
of great value. The small bulk of oil and its great heating value 
make it suitable for marine work, when the danger of storing 
is minimised by using heavy oil. A vertical double cylinder 



THE PRIESTHAN OIL ENGIXB. 



303 



5 H.P. engine of this type has been fitted up on board a steam 
launch. It runs at 250 revolutions a minute, has a cylinder 
diameter of 7 inches, with 7 inch stroke. The construction and 
working are similar to those of the horizontal single cylinder 
motor already described, except that with two cylinders an explo- 
sion every revolution is obtained. The engine can be reversed 
or stopped by a hand wheel acting on the main driving shaft, 
and is very easily worked. Hitherto these and other types of 
Priestman engines have only been made for small powers, but 
larger sizes will no doubt be produced in time. They are also 
used as motive power for barges, of which there are two on the 
Manchester Ship Canal, driven by a 10 H.P. Priestman oil engine. 
The fog signals on the Point of Ayr and Corse wall lighthouse 
stations are worked by three 5 H.P. engines, compressing the air 
to 40 lbs. per square, inch. Each engine uses 6 pints of oil per 
hour. Another installation is at Oxo in Norway, where an 
11 H.P. engine compresses air to 60 lbs. per square inch. The 
oil used is of 0*82 density, and the consumption 11 lbs. per hour. 
Trials. — Several excellent trials have already been made on 
this engine, chiefly by Professor Unwin. In 1889 he tested at 
the Agricultural Show at Plymouth a 5 H.P. horizontal Priest- 



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^-Ciearance votume . — >♦ •6lro4» colunif'' — — 

Fig. 113. — Priestman Oil Engine— Indicator Diagram. 

man motor of the newest type, with 8^-inch cylinder and 12-inch 
stroke. Five trials were made with two kinds of oil, and every 
care was taken to ensure accurate results. In the first test an 
American oil, "Eoyal Daylight," was used, of 0*793 density, 
flashing point 77* F., and heating value about 19,700 B.T.U. 
per lb. The four other trials were made with Russian oil, of 



304 



PETROLEUM ENGINES. 



density 0*822, flashing point 86"* F., and calorimetric value taken 
at 19,500 B.T.U. per lb. Fig. 113 gives a diagram taken during 
the trials with Russian oil. In trials at full power the following 
results were obtained : — 

Results of Tbial by Professor Unwin ok a 5 U.P. 
Priesthan Engine. 



Name of Oil. 


^ 


Mean 
Efficient 

BqVlnS. 


B.H.P. 


L H.P. 


Efflelener. 


B.H.P. 


U^ 
L'ffp. 


American "Day- 

Ught," . . 
Russian, . 


204 
207 


63-20 
41-38 


7-72 
6-76 


9-36 
7-40 


0-82 
0-91 


Lb. 

0-84 
0-94 


Lb. 
0-09 
0-86 



The heat expenditure was as follows: — Heat utilised, 16-12 
per cent.; carried away in jacket water, 47-54 per cent.; in 
exhaust gases, 26*72 percent.; lost by radiation and unaccounted 
for, 9*61 per cent. The engine was examined at the end of the 
trials, and found to be perfectly clean and free from smoke or 
deposit, and the points of the electric wires were not coated with 
carbon. 

Another trial was carried out on a 5 H.P. Priestman engine 
by Professor Unwin at Hull in December, 1891. The same oils 
were used as before — namely, Russolene and American Day- 
light — and tests were made, as in the other trials, with the 
engine running at full power, half power, and light. The trials 
with full load lasted nearly three hours. With Russian oil the 
mean speed was 208 revolutions per minute, mean pressure 
41-38 lbs. per square inch, B.H.P. 6*76, T.H.P. 7*40, and the 
mechanical efficiency 0*91. The consumption of oil was 0*94 lb. 
per B.H.P., and 0*86 lb. per I.H.P. per hour. With the 
American oil slightly higher results were obtained. Details of 
these experiments will be found in the table at p. 404. Two 
trials at full and half power were made on a semi-portable 
4^ nom. Priestman engine, by Professor Unwin and Mr. Pidgeon, 
at the Plymouth Agricultural Show in 1890. They differ very 
little from those already given, except that Broxbourne light- 
house oil was used, of 0*810 density, and having a heating value 
of about 19,000 T.U. per lb. In the full power trial, the engine 
indicated 5*24 H.P., B.H.P. 4-49, cylinder 8*5 inches, and 
12 inch stroke. The mean pressure was 33*96 lbs. per square 
inch, consumption of oil 1*06 lb. per I. H.P. and 1*24 lb. per 
B.H.P. per hour. In all these trials the amount of heat sup- 
plied, and the different items of heat expenditure were carefully 
noted. Full particulars will be found in Professor TJnwin'a 
paper already quoted. 

Another trial was carried out in 1890 by Mr. W. T. Douglass 



THE PRIESTMAN OIL ENGINE AND YARROW SPIRIT LAUNCH. 305 

on a nom. 25 H.P. double-cylinder Priestman engine, driving an 
electric plant. The B.H.P. was 25-5, and the oil consumed per 
B.H.P. per hour 0-88 pint. The progressive decrease in the oil 
consumption per H.P. in these engines, as shown yearly at the 
Eoyal Agricultural Society's meetings, is striking. In 1888 
1*73 lb. of oil was required per B.H.P. per hour, in 1889 
1'42 lb. At Plymouth the consumption was 1*24 lb., and in 
the latest trials by Professor Unwin in 1891 0-94 lb. per B.H.P. 
per hour. These results obtained at Agricultural Shows are 
satisfactory, because the advantage of this motor is chiefly as 
an agricultural portable engine, in fields and other places where 
gas and steam are not available. 

American Type. — The engine has been taken up by a firm 
in America, where oil is very cheap, and there is a great demand 
for machinery for light work and electric illumination. The 
type there made resembles the straight line steam engine of 
Professor Sweet- Professor E. Thompson of America uses pure 
silver igniter electrodes, in lieu of platinum, as in the English 
engines. He considers them better, and the wires do not 
get blackened or coated. These silver contacts have been at 
work for several weeks without cleaning. His oil engine is 
started with gas, which is more convenient than oil for the lamp, 
and it runs at about 260 revolutions per minute. Another 
American authority using the Priestman engine had trouble 
with the internal passages and back of the cylinder, which 
became choked with soot, until pure air, instead of air not 
filtered, was admitted. The engine in this case was used for 
pumping water from a mine. 

Up to the present time Messrs. Priestman make their engines 
in 10 sizes, 1 to 25 H.P. ; a 5 H.P. nominal has a cylinder 
diameter of 8^ inches, with 12-inch stroke. The two largest 
sizes of the horizontal types are with double cylinders only, the 
others are single cylinder engines. Theses are chiefly for land 
motors. The engines run at from 220 revolutions for smaller 
sizes down to 160 revolutions for larger. The marine type of 
engine is made vertical, in four sizes and with double cylinders, 
from 2 to 25 nominal H.P., and runs at from 270 to 220 revolu- 
tions. For portable engines, 3 single cylinder types are made, 
from 5 to 11 nominal H.P., running at about 170 revolutions 
per minute. Messrs. Priestman have already constructed from 
400 to 500 engines. 

Zephyr Spirit Launch. — The Yarrow "Zephyr" spirit launch 
stands in a different category to all other oil engines, because it 
is the only motor using pure and highly volatile petroleum spirit, 
having a density of 0'68, and evaporated in the same way as 
steam. Sometimes the spirit is also used as the fuel. Its evapo- 
rative power, and therefore its heating value, is not so great as 
ordinary kerosene, about 12 per cent, less, but it has a higher 

20 



306 



PETROLEUM EK0INB8. 



pressure for a given temperature than steam, as shown by Professor 
Robinson's tests. At a temperature of 155° F. it has a pressure 
of 10 lbs. per square inch. At 212° F. (the temperature of boiling 
water) its pressure is 40 lbs. per square inch, while at 300° F., 
with steam equal to 50 lbs. pressure per square inch, petroleum 
spirit has a pressure of about 115 lbs. It is easily evaporated, 
and may be cooled without condensing to a temperature of 130° F. 
Thus the range of temperature is greater, for the same pressures, 
with petroleum spirit than with steam, and since efficiency 
depends theoreticsJly upon this range, more work should be 
obtained under similar conditions. 

The following table exhibits the results of tests undertaken by 
Messrs. Yarrow, to determine the relative power of steam and of 
petroleum spirit, when evaporated in a boiler. The fuel used 
under the boiler in both cases was gas, the consumption of 
which was measured by a meter. 



Table of Comparative Workikg Results of Steam and 
Petroleum Spirit. 



Boiler Experiment. 



Gas oonBumption in cubic feet per hour, . 
Mean pressure of spirit in coil (lbs. per sq. inch), 

„ speed — ^revolutions per minute, 

„ pressure in boiler (lbs. ), 

Tension on brake in lbs., 

Work obtained on brake in ft. -lbs. per minute. 
Work in cylinder „ „ ,, 



steam 


Spirit 


Braporated. 


Bvaporated. 


82-20 


83-48 


,. 


56-80 


312-6 


652-2 


37-99 


30-07 


1-154 


1-222 


2524 


4722 


5199 


11975 



Eyaporation of Petroleum Spirit. — As petroleum spirit eva- 
porates at a lower temperature than steam, less heat is put into 
it to raise it to the same pressure ; in other words, if the same 
amount of heat be applied to it as to steam, a much higher pres- 
sure and more work are produced. But as less heat is required 
to evaporate it, less heat is withdrawn in the exhaust; the 
quantities of heat both imparted and abstracted are smaller 
than with steam, for a given amount of work. At atmospheric 
pressure nine times as much spirit as water will be evaporated 
by the same amount of heat, but the spirit being very volatile, 
it does not increase as much in volume, and only expands to 
one-fiflh the volume of steam. As a working agent petroleum 
vapour turns more heat to account than steam ; the one serious 
drawback is its inflammable nature, and difficulty of storage. 

Zephyr Iiaiuich. — In the ** Zephyr" launch, the spirit is 
introduced into a spiral coil enclosed within a casing of non- 
conducting material, called the vapour generator, to which heat 
is applied. In its passage through the coil the spirit is evaporated, 



THE YABROW SPIRIT LAUNCH. 307 

and passing into the cylinder drives tJie piston forward by its 
pressure. The exhaust products are discharged by the action of 
the engine into two cooling pipes, where they are liquefied and 
forced back to the supply tank, an air-tight copper vessel in the 
bow of the ship. Thus the same spirit is used over and over 
again, with very little waste, and the working principle and 
action are similar to those of a surface condensing steam engine. 
The risk of explosion from the inflammable spirit is also greatly 
reduced, since it passes through a complete closed cycle of opera- 
tions, and is never brought in contact with the external air. The 
danger is also avoided of storing a large quantity of petroleum 
spirit ; a small amount is sufficient, if used continuously in this 
way, to produce power for many hours. A small "Zephyr" 
launch, 36 feet by 6, running at 8 miles an hour, can carry fuel 
enough for 200 miles. The action of the engine is first utilised 
as a pump, to force the spirit from the tank to the vaporising 
coil, and then to drive the exhaust vapour back to the tank. 

The process of heating the spirit, or generating the vapour in 
the copper coil, presents greater difficulties. There are two ways 
of obtaining this heat. The simplest method is to use part of 
the petroleum spirit as fuel, as well as working agent. Some- 
times it is allowed to pass through a valve to a ring gas burner 
under the coil, ignited in the usual way, and the flame evaporates 
the spirit above. A constant supply being maintained, with a 
proper proportion of air, the flame bums steadily, and the heat 
is continuously generated. This arrangement has the great 
disadvantage of requiring the storage of a large quantity of the 
dangerous spirit to feed the burner, although in the coil itself 
only a comparatively small portion is needed, to replace the loss 
by leakage. A much better plan, and that generally adopted, is 
to use ordinary heavy petroleum, which can be stored without 
danger, to heat the spirit. A small air-pump driven by the 
engine forces air into the oil tank, and a mixture of oil vapour • 
and air is injected as spray into the fire box or furnace beneath 
the coil, in the same way that liquid fuel is broken up, injected 
and burnt under a locomotive boiler. After being completely 
vaporised by the heat, it is mixed with more air, and burns with 
a continuous flame like a Bunsen burner. With this method 
there is little risk of explosion, but a separate tank is required 
for the mineral oil, and power to drive the air-pump, diminishing 
slightly the total useful work of the engine. 

In the Zephyr spirit launch the engine and spirit generator 
are carried in the stern of the boat, and the spirit supply in the 
bow, to balance the vessel, leaving the centre free for goods and 
passengers. The machinery is very light, and the engine, tank, 
<&c., weigh only 1 ton in a boat 36 feet long. This class of engine 
is specially adapted for small launches and torpedo boats, but is 
unsuitable for large powers or great speeds. It can easily be 



308 PBTBOLBUM EKGINB6. 

started in from two to five minutes after lighting the burner, and 
like other vessels driven by petroleum, the Zephyr spirit launch 
is smokeless. The consumption of fuel for burning is about one- 
third of a gallon per H.F. per hour. 



CHAPTER IV. 
OTHER OIL ENGINES. 

Contents. — ClasaificAtion — Hornsby- Akroy d — TruBty — Root's Petroleum 
Motor— Otto— GriflRn — Weatherhogg— Lenoir — Simplex— S^curit^ — 
Ragot — Tenting — Durand — Forest — Capitaine— Daimler — Adam — 
Altmann and KiippermaDn—Lude- Vulcan. 

ClasBsifloation. — The Priestman oil engine is at present one 
of the few motors adapted for driving only with oil. Most 
other oil engines were originally constructed to use gas as the 
motive power, and the oil carburetting apparatus has been added 
afterwards. All oil motors, however, including the Priestman, 
employ the usual gas engine cycle, the series of operations 
proposed by Beau de Rochas and adopted by Otto, comprised in 
four strokes of the piston, with one explosion every two revolu- 
tions. Excellent results are obtained with this cycle, and the 
engines work more smoothly than gas motors, owing to the 
peifect lubrication alSbrded by the oil. The action and method 
of utilising the power developed does not dilfer from that 
hitherto described. The difference consists in the treatment 
of the petroleum. In no two motors is the process of burning 
the oil precisely the same, though in all it is sprayed or broken 
up by the addition of air or steam, and vaporised by applying 
heat. The following classification, given in ^A^ jL'ngineer of 
June 24th, 1892, of the methods by which the oil is evaporated, 
may be found useful : — 

il. Engines in which the oil, before entering 
the cylinder, is converted first into oil spray, 
forming an oil shower, and next into vapour in a 
hot chamber. 
2. Engines in which the liquid oil is injected 
into a prolongation of the eng^e cylinder, a hot 
cartridge chamber or combustion space, where it 
is converted into vapour or gas. 
3. Engines in which the oil is converted into 
vapour or gas in a chamber contiguous to the 
cylinder, and communicating with it by a valve. 
4. Engines in which the oil is converted into 
vapour or gas in a separate chamber, heated apart 
from the cylinder. 



OTHBB OIL ENGINES. 



309 




The charge thus prepared for use is fired in one of ^the three 
following ways : — 



310 PETROLEUM ENGINES. 

1. By electricity. 

2. By a tube heated by an oil flame. 

3. By spontaneous ignition of the oil vapour, due to its com- 
pression, and to the heat of the vaporising chamber. 

The Hornsby-Akroyd oil engine has one peculiarity which 
distinguishes it from the other heat motors hitherto described. 
It has neither hot tube, electric spark, nor slide valve with flame^ 
but the charge is fired according to the method described in the 
third division above. The oil is injected into a red hot chamber 
(or cartridge) at the back of the cylinder, into which heated air, 
compressed by the back stroke of the piston, is forced as it 
reaches the inner dead point, and the mixture ignites spontan- 
eously. The internal surface of this chamber is provided with 
radiating ribs, to aflbrd a greater heating area. It is maintained 
at a red heat by the combustion and explosion of the oil and 
air at every other stroke. The engine is of the usual four-cycle 
type, and the functions of admission, compression, explosion 
plus expansion, and exhaust are carried out during four con- 
secutive strokes. The Hornsby-Akroyd is perhaps one of the 
simplest oil engines hitherto produced. Its action and the 
method of vaporising the oil will be best understood from 
Fig. 114. 

Here A is the motor cylinder, P the piston, B the compression 
space, into which the piston does not enter, and the cartridge 
or combustion chamber beyond it. The walls of the cylinder are 
cooled by a water jacket shown at W, but the combustion cham- 
ber C is surrounded only with an air jacket, to keep it at a 
uniform temperature. The highly heated charge in it is pre- 
vented by the intermediate compression space B from coming in 
contact with the cooler cylinder walls. Below is the lamp L> 
used to heat the combustion chamber or vaporiser at starting. 
The oil for this lamp is drawn from the same tank as that feed- 
ing the engine. Air is admitted above it from a fan, F, worked 
by hand. A small piece of asbestos or other absorbent material 
is pushed through the little plug at p, dipped in the oil and 
ignited, and as the air enters it rapidly ians the oil into a 
fierce flame, which rushes out through the hole at the top, and 
in a few minutes heats the vaporiser C. As soon as the latter 
is red hot, the current of air is stopped, the lamp extinguished, 
and the engine then works automatically, aft^r a few turns of 
the flywheel by hand. The T-shaped air and exhaust valves, 
seen at c and d, are worked by cams and levers through an aux- 
iliary shaft, geared to the crank shaft in the proportion of 2 to 1. 
These valves communicate with the cylinder through the same 
opening, in order that the heat of the exhaust products may 
warm the fresh air admitted through valve d. The temperature 
of the air is further raised by the heat of the cylinder, and of the 
back compression stroke. As the piston reaches the inner dead 



HORNSBT-AKROTD OIL ENGINE. 311 

point, it forces the compressed air into the red hot cartridge 
space, where a small quantity of oil is injected into it. The oil 
is drawn from a tank in the base of the engine, and a few drops 
are delivered by the little oil pump O at every other stroke, 
through a narrow tube and simple nozzle into the hot chamber 
C. The oil pump, worked by the same lever as the exhaust, 
sends the oil to the chamber in a fluid condition, and not, as in 
other oil engines, in the form of spray. The heat of chamber C 
and the pressure of the air charge immediately vaporise it ; 
the maximum pressure of the inner dead point causes the igni- 
tion, and the piston is driven out. The burning charge passes 
into the compression space of the cylinder through a very small 
passage, s, that as little heat as possible may be dissipated 
through the walls, and the pressure of the flame increased. The 
exhaust is opened by the side shaft worked from the main crank. 
The centrifugal governor G acts on the little horizontal valve 
through which the oil is admitted to the vaporiser, and closes 
the narrow tube when the speed exceeds the normal limits. At 
the same time it opens a little bye-pass valve, and the oil is sent 
back to the tank ; thus the oil pump works continuously, the 
governor regulating only the direction in which the oil passes. 
The valve box has a water jacket, to keep the oil cool till it 
reaches the vaporiser. The quantity conveyed to the engine 
to form a charge is regulated by adjusting the stroke of the oil 
plunger. The air being dry and hot, the engine has to be lubri- 
cated in the usual way. 

Method of Vaporisation. — The peculiar feature of the 
Hornsby-Akroyd engine is that no attempt is made to vaporise 
the oil or convert it into spray, until it is actually injected into 
the combustion chamber. Hence the density of the oil is a 
point of no importance, and heavier petroleum may be used than 
in most other engines. The specific gravity of the oil is usually 
about 0*850, and its flashing point 150° F., but the engine will 
work with oil of specific gravity 0-864, flashing point 220° R, and 
weighing 8^ lbs. to the gallon. Thus it is one of the safest and 
simplest of oil motors, and these two advantages should make 
it popular, when better known. The quantity of oil injected 
at a time is very small, only about -015 cubic inch per stroke of 
the oil pump in a 6 H. P. engine. The proportion of air present 
is so large that combustion is complete, and there is said to be no 
heavy residuum. The exhaust products are employed to warm 
the incoming air, the heat of combustion to vaporise the oil, and 
raise the temperature of the next charge to the ignition point. 
Much of the heat generated is thus utilised, while if very heavy 
petroleum is used as the working agent, the heat of the jacket 
water may be employed to keep it in a proper fluid condition. 
The consumption of the engine is about one pint per hour 
per B.H.P., and the cost of working under id. per B.H.P. per 




312 PETROLEUM ENGINES. 

hour. Fig. 115 gives a diagram of an engine indicating 674 H.P.,- 
taken by Professor Robinson. The specific gravity of the oil 

was 0*854, flashing point 
220** F., and the engine 
made 224 revolutions per 
minute. The consump- 
tion of oil wan about 0*9 
pint per B.H.P. per hour. 
The engine is made by 
Messrs. Hornsby & Sons, 
' Grantham, in ten sizes 
Fig. 115.— Homaby.Akroyd Engine— ^^m 1^ to 19 B.P., 

Indicator Diagram. and runs at 250 to 200 

revolutions per minute. 
Trusty. — A different method of vaporising the oil has been 
adopted in the Trusty engine, brought out by Messrs. Weyman 
& Hitchcock, of Guildford, and resembling the gas engine of 
the same name, with the addition of an apparatus for gasifying 
the oil. Some years ago an engine was invented by Mr. Knight 
of Farnham, in which the oil was vaporised in a jacket round 
the combustion chamber. The patent of this engine has now 
been acquired by the makers of the Trusty, who have applied 
and improved the principles of the early motor. In the Knight 
engine, ignition was obtained by making a flame, produced by 
the action of bellows, play at the right moment upon a coil of 
platinum wire. In the Trusty, the charge was at first fired by 
directing an air jet upon an oil flame, but this method has now 
been abandoned in favour of ordinary tube ignition. 

The engine is horizontal and single acting, with one cylinder ; 
the action is similar to that described in the Trusty four-cycle gas 
engine (p. 133). Fig. 116 gives an end view, with the method 
of introducing the oil into the vaporiser. The latter, shown at 
V, consists of a jacket fitting round the compression end of the 
cylinder, and divided internally into sections. The air admission 
and exhaust valves, S and S^ are worked by levers L and Lj, firom 
a side shaft gearing into the main shaft in the proportion of 
2 to 1, as in the Trusty gas engine. At o, o^ are the screws for 
adjusting the valves, the exhaust outlet is at K The method 
of vaporising the oil is original. It is drawn through the 
pipe p from a tank below the engine, and pumped from the 
horizontal pump P through the second pipe pp into the column 
or receiver C at the top of the engine. From here it passes into 
the jacket or vaporiser Y through a small glass tube just above 
the cylinder, shown in Fig. 118, through which and through 
valve H it is admitted drop by drop into V, where it is imme- 
diately vaporised. The igniting tube I is at the back of the 
<;ylinder and evaporating chamber, and is maintained at a red 
heat by a lamp J. The rod Q actuating the oil pump P is 



TRUSTY OIL ENGINE. 



313 



worked at M by a hit-and-miss device, controlled by the pen- 
dulam governor G. If the speed is too great, the projection on 
thegovernor cannot reach 
the notch on the valve rod 
in time, a lever D is in- 
terposed, and theoil pump 
does not work. The lever 
also acts upon the valve 
n, admitting the oil to 
the vaporiser, and the 
supply is thus doubly 
checked by the governor. 
As the combustion of 
the charge takes place in 
the compression chamber, 
the jacket round it be- 
comes so hot that the oil, 
as it enters, is instantly 
turned into vapour. The 
out stroke of the piston 
draws in a charge of fresh 
air through the admission 
valve Bij and at the same 
moment,through valve H, 
the vaporised oil is ad- 
mitted into the compres- 
sion chamber from the 
jacket. The oil vapour 
and air mingle in the 
cylinder, and are compres- 
sed by the return stroke 
of the piston, driven up 
the tube, ignited in the 
ordinary way, and explosion and expansion of the charge 
follow. The oil is vaporised by the heat of explosion, during 
which the highest temperature of the cycle is reached, and 
greater pressure? are said to be attained than in the Priestman 
engine, where the oil is vaporised by the heat of the products 
of combustion only. The Trusty engine also runs at higher 
speeds than the Priestman, and gives a good heat efficiency. 
The special feature of the engine is the vaporisation of the oil 
drop by drop, as it is required, the quantity being regulated by 
the stroke of the oil pump, which in a 4 H.P. engine is about 
^incb diameter. As the oil is not sprayed before it enters the 
•cylinder, neither its density nor the varying temperature at 
which it evaporates affect the working of the engine. There is 
sometimes a little residuum, because the petroleum is turned 
into true oil gas by the heat of combustion. The parts and 




Fig. 116.— Trusty Oil Engine. 



314 



PETROLEUM ENGINES. 



passages being easily accessible, the occasional cleaning required 
is carried out without difficulty. Broxbourne lighthouse oil, 
distilled from Scotch shale, with flashing point ISO** F. and speci- 
fic gravity 0*81, is usually 
employed, but a much 
heavier oil with flashing 
point 250* F. may be used. 
Trials. — In a two hours' 
trial on a Trusty oil engine 
"^ made by Mr. Beaumont, 
the specific gravity of the 
oil was 0*8 10. The engine 
indicated 6-2 H.P., and 
gave 4*28 H.P. on the brake; the mechanical efficiency was 69 
per cent, and the speed 230 revolutions per minute. The oil 
used amounted to 0-963 lb. per B.BLP., and 0667 lb. per 
I.H.P. per hour. All the items of heat expenditure were care- 
fully noted ; particulars will be found in the table at p. 404. 
The ratio of heat shown in the indicator diagram as work done, 




Fig. 117.— TruBty Oil Engine 
Indicator Diagram. 




Fig. 118.— Trusty Oil Engine— External View. 

to that supplied in the oil was about 20^ per cent. Fig. 117 
gives a diagram taken during the trial, and Fig. 118 an external 
view of the engine. The marker's types range from ^ H.P. to 1 2 
H.P. nom. in eleven sizes ; the speed per minute is 220 to 180 
revolutions. 

Boot's Petroleum Motor. — A small engine, in which the 
oil is vaporised in a new and original manner, has been 
used to drive a little boat running on the Thames. The 
engine is known as Boot's Petroleum Motor, and the launch 
was built by Messrs. Vosper & Co., of Southampton. It 



OTTO OIL ENGINE. 315 

is a vertical double -cylinder engine, the crank, shaft, and con- 
necting-rods being all covered in. The petroleum is admitted 
from a receiver at the top, and falls first through ports into 
grooves in a reciprocating bar or lever. Movement is communi- 
cated to the latter, through a series of vibrating levers, from an 
eccentric driven from the crank shaft by wheels. From hence 
the oil is led through pipes into an annular vaporising chamber 
in the centre of the engine. This chamber is placed above the 
space containing the ignition tubes, which are heated by a jet 
burner below them, fed with fine oil spray. One cylindrical 
casing encloses both the vaporiser and the hot tubes. Air enters 
through holes at the bottom of the vaporiser, and passing 
upwards is heated by the flame and the ignition tubes. It ia 
then led off through pipes, heating all the ports and passages, 
through which the oil filters down into the vaporiser, before 
it returns to the hot chamber. Thus the air, heated by the 
flame and hot tubes, is impregnated with the oil, and carries, 
back a certain quantity to the vaporiser, the heat from the 
enclosed ignition chamber being sufficient to turn the oil into 
vapour. From here the charge of oil and air passes to the motor 
cylinders through automatic admission valves, held on their seats 
by springs, and raised by the pistons in their descent. Tho 
mixture is ignited, and drives down the pistons in the usual 
way. The exhaust valves at the top of each cylinder are worked 
by the same vibrating levers and eccentrics as those admitting 
the oil. In spite of the numerous ports and passages through 
which the oil has to pass, there is apparently no deposit. Draw- 
ings of this engine will be found in The Engineer, September 30, 
1892. 

Otto. — ^The Otto may truly be called the prototype of all 
modern gas engines, and to its many advantages has now been 
added that of working with petroleum, where gas is not avail- 
able. In the oil motor introduced by Messrs. Orossley the usual 
four-cycle type is adhered to in every respect, and the engine 
works in the same way as with gas, except that in some cases 
electric ignition has been employed. Besides the ordinary parts, 
there is an oil pump driven trom the side shaft, and also a. 
vaporiser at the back of the engine. Two methods of volatilis- 
ing the oil have been adopted. With the first, only light oil or 
benzoline can be used. It is stored in a small receiver, and 
heated by the exhaust gases, which are carried along the bottom 
of the receiver. The level of the oil is maintained constant by 
a float. Air, sucked in by the out stroke of the piston, enters 
the receiver, and is drawn up from the bottom of the liquid 
through a perforated disc, in order that it may pass through the 
oil in as many streams as possible. From hence the air, now 
carburetted, is conveyed, through a vessel filled with gravel to 
cleanse it, to the admission valve, where it is mixed with freshi 



316 PETROLEUM ENGINES. 

air drawn in from the base of the enjs^ine, before it enters the 
motor cylinder. The charge is fired electrically, and the spark 
is produced by interrupting the current from a small dynamo, 
by means of a projection on the distributing shaft. This method 
has been chiefly used in Germany. 

In the more modern applications of petroleum to drive the 
Otto engine the use of inflammable spirit is abandoned. The 
oil to be vaporised has a specific gravity of 0-820 and 30° 0. 
= 86' P. flashing point, but heavier oil, flashing at 120° F., 
can be employed. A current of air at considerable pressure is 
drawn, by the suction stroke of the piston, past a nozzle from 
which oil is sprayed into it. This oil is drawn by gravitation 
from a tank above the engine. The vapour thus formed passes 
into a hot chamber, and from thence into the cylinder. It is 
compressed by the next back stroke of the piston to a pressure 
of 200 lbs. per square inch, together with a charge of fresh air 
supplied through an automatic valve to dilute it. Ignition is 



^tootbt.iieriiq.in 




Fig. 119. — Otto Petroleum Engine — Indicator Diagram. 

•obtained by a tube heated by a lamp of special shape, fed with 
petroleum and air from a separate vessel. The pressure in this 
receiver can be raised by hand to about 40 lbs., and will last for 
a considerable time. The lamp is also used to heat the vaporiser 
at starting. If the speed of the engine be too great, the governor 
closes the admission valve, and keeps the exhaust open. The 
burnt products re-enter the cylinder at the next out stroke, and 
its temperature is therefore not much reduced. In a trial 
made with a 4 U.P. nom. Otto petroleum engine (diagram, 
Fig. 119) the B. H.P. was 5-3, the engine made 212 revolutions 
per minute, and consumed 0*7 gallons of oil per B.H.P. per 
hour. Messrs. Orossley make this class of engine in three sizes, 
2 II.P., 4 H.P., and 9 H.P. nom., running at a speed of about 
200 revolutions per minute. 

GrifOLn. — The Griffin oil engine, lately brought out by Messrs. 
Griffin & Co., of Bath, must be distinguished from the Griffin 
gas engine, made by Messrs. Dick, Kerr & Co., of Kilmarnock. 
The ordinary Beau de Rochas cycle is used, and there is an 
•explosion every two revolutions, as in the Otto. It is a single- 



GRIFFIN OIL ENGINE. 317 

cylinder horizontal engine, and the admission and exhaust valveft 
are driven from a side shaft gearing on to the crank shaft in the 
usual way. The novelties claimed for this engine are the method 
of vaporising the oil, of ignition, and of governing. The 
vaporiser is placed in the bed plate, at right angles to the 
cylinder. The oil drawn from a tank in the base is injected into 
the vaporiser in the form of fine spray. The spraying jet con- 
sists of two concentric nozzles, one inside and set behind the 
other. The oil is injected from the inner nozzle into the outer, 
and the air, at a pressure of 12 lbs. per square inch, carries the 
line oil particles to the vaporiser. Here they are converted into 
vapour by the heat of the chamber, which is surrounded by a 
passage containing the exhaust gases, and ribbed internally to 
afford greater heating surface. Much of the heat of explosion 
must pass into this chamber. As the oil vapour emerges from 
the vaporiser at the other side of the engine, it is carried 
through a curved pipe to the cylinder above. Below this pipe is 
a perforated box, through which air is drawn to mix with the 
charge. This air is also heated, because the exhaust gases are 
carried through the curved pipe, before they are discharged to 
the atmosphere. The charge then enters the cylinder, and is 
ignited by the tube, kept at a red heat by an oil spray Bunsen 
flame. The ignition of the charge is also original. A small 
quantity of oil is conveyed from the tank to a little vessel, where 
it is drawn upwards by capillary attraction. It is next broken 
up into spray by a blast of air from the air pump, and carried 
forward into a pipe kept at a high temperature by the heat from 
the burner. Here it is vaporised, ignited at the Bunsen burner, 
and the flame plays continually on the tube. 

Gk>vemmg of Griffln and other Oil Engines. — To regulate 
the speed of an oil engine by reducing the number of explo- 
sions, cutting off the supply of oil, and passing air only 
through the cylinder, is not altogether desirable. If there is 
no explosion, no heat can be communicated from the exhaust 
gases to the vaporiser. The latter becomes chilled, and the 
next time oil is admitted, the temperature is not high enough 
to evaporate it completely ; unburnt oil passes into the cylinder, 
and waste and deposit of residuum are the result. In the Griffin 
engine the centrifugal governor acts upon two valves placed side 
by side, one admitting the completely mixed charge to the 
cylinder, the other discharging the exhaust gases, after they 
have heated the vaporiser and the incoming charge. If the 
speed is too great, neither of these valves act, and the admission 
of air to the vaporiser is also suspended. As no charge either 
euters or leaves the cylinder, there is little waste of heat. The 
engine works with ordinary petroleum of 0*80 specific gravity, 
and 100° F. flashing point. At starting the air pump is worked 
by hand, and the oil spray jet thus formed is ignited, and enters 



318 PETROLEUM ENGINES. 

the vaporiser as a strong flame. In ten minutes it is sufficiently 
hot to work the engine. The air pump is then connected to the 
eccentric and side shaft driving the valves. Drawings of this 
engine will be found in Engineering, November 4, 1892. 

Weatherhogg. — The Weatherhogg petroleum engine forms 
the solitary exception to motors employing the Beau de Rochas 
four-cycle. It is a six-cycle engine, with a scavenger charge of 
air introduced and expelled between each admission of oil vapour 
and air. The oil is injected by a pump into a vaporisiag coil 
heated by a blow-pipe flame, and in its onward passage to the 
cylinder is diluted with the proper proportion of air. Ignition 
is by hot tube. This engine appears to be still in the experi- 
mental stage. 

Bocket. — A petroleum engine called the " Rocket" has lately 
been introduced by Messrs. Robert Stephenson & Co., of New- 
castle-on-Tyne (Kaselowski's Patent), in this motor, petroleum 
from a tank above the cylinder flows by gravity into the 
vaporiser, where it is sprayed by an air current, and vaporised 
by the heat of the exhaust gases. From thence it passes to the 
engine, being diluted on its way with the proper proportion of 
air. No pumps are required for the oil, *fec. Hot tube ignition 
is used, with a timing valve worked by a cam on the auxiliary 
shaft. The governor is so arranged that when the normal speed 
is exceeded, the supply of oil vapour is cat off, and no compres- 
sion of the waste gases in the cylinder takes place. 

Lenoir. — In later oil engines the tendency is certainly to use 
heavier and less inflammable oils, as shown by the modifications 
in the Otto. In the French Lenoir motor a carburator has been 
added, in which the more dangerous lighter oils are employed. 
Fig. 1 20 gives a view of this engine working with carburetted air ; 
the action is the same as in the modern Lenoir gas motor. The 
position of the carburator above the cylinder is near enough for the 
heat of the engine to keep the oil in a proper fluid condition, and 
counteract the cold of evaporation, but not near enough to con- 
vert the oil into vapour. Hence the use of lighter petroleum, 
which can be evaporated without much heat. The carburator 
is attached to the engine, and a very slow rotatory movement is 
transmitted to it by a small strap and worm wheel, running at 
4 revolutions a minute. The air is drawn into the carburator 
through a Altering vessel, and through the tube to the right 
of the carburator in the drawing. When charged with petroleum 
vapour it is carried off to the engine through the tube at the 
other side, the shape of which prevents any unevaporated 
particles of carbon from reaching the cylinder. 

Lenoir at first divided the carburator or rotating cylinder 
into comjiartments filled with sponge or other porous substance, 
which was impregnated with light oil having a specific gravity 
of 0*65. It was found that the air charged with this volatile 



LENOIR OIL ENGINE. 



319 



spirit soon became decarburetted, and the apparatus was conse- 
qaentlj remodelled. In the cylinder now used, a number of 
small semi-circular troughs are set round the inner circumferenca 




Fig. 120. — Lenoir Petroleum Engine— External View. 

The bottom is half filled with gazolene/and as the cylinder rotates, 
the troughs pass successively tlirough the oil, and fill themselves. 
Baised by the continued movement of the carburator, each in 
turning is emptied of its contents, which fall in a fine rain or 
mist back into the oil below. 
Thus the cylinder is always full 
of pulverised gazolene, thoroughly 
saturating the air as it passes 
through. The carburet ted air 
is then conveyed to the motor 
cylinder through a passage or 
bulb, in which metallic wires are 
fixed, to prevent the flame from 
shooting back into the carburator. 
; v> A series of careful experi- 
ments were made by M. Tresca 
on a Lenoir engine working with carburetted air. Two engines 
were tested, of 2 H.P. and 4 H.P. nom ; the density of the 
oil used was 65. In the first the B.H.P. was 1-96, and 
consumption of volatile spirit 106 pint per B.H.P. per hour; 




Fig. 121. — Lenoir Petroleum 
Engine— Indicator Diagram. 



320 



PETROLEUM ENGINES. 



in the second the B.H.P. was 4-15, and consumption of oil 
ri4 pint per B.H.P. per hour. The Lenoir petroleum engine 
has also been used for portable motors, and to propel a steam 
launch. Fig. 121 shows an indicator diagram taken during the 
second trial by M. Tresca. 

Simplex. — The Simplex gas engine-of MM. Delamare-Debout- 
teville and Malandin, made at Rouen, and described at p. 140, 
has also been supplemented by a carburator. In this apparatus 
the density of the oil used is rather greater than in the Lenoir, 

but as the heat of the engine 
does not vaporise it, heavy 
petroleum cannot be employed. 
Fig. 122 gives a view of the 
Simplex carburator, and ex- 
plains the working method. 
R is the tank, usually open at 
the top to the atmosphere, and 
containing liquid petroleum of 
0-65 to 0-70 density; D the 
valve for admitting it into the 
column E ; B is a spiral horse- 
hair brush, which breaks the 
oil falling on to it into spray; 
at C is the casing round the 
column, heated by the hot water 
from the motor cylinder jacket. 
This water leaves the jacket 
at a temperature of 60' to 70* 
C, and falls to 40" or 50' C. 
by the time it reaches the 
carburator, where it helps to 
counteract the cold produced 
by evaporation. F is the small 
cock from which water, also 
drawn from the jacket, falls 
in a light shower into the 
column, and mingles with the narrow stream of oil entering 
through D from R. The water helps to break up the oil into 
finer spray, and also to purify it, by holding in solution the 
coarser particles of dirt. The oil and water filter down through 
the spiral brush into the vessel L below, to which they are 
admitted through the valve V. Here the water and impurities 
are deposited at the bottom, and the water kef)t at a constant level 
by the overflow pipe N. The suction stroke of the piston draws air 
down from the top of the carburator through the column C, which 
is filled witli oil spray and water, and this air, charged with petro- 
leum vapour, is carried off from the vessel L through the pipe S 
to the motor cylinder. A safety valve is placed in this pipe, to 




Fig. 122.— Simplex Carburator. 



^^S^GUBIT^" OIL ENGINE. 321 

hinder the flame produced by the explosion of the charge from 
shooting back into the carburator. The hot water prevents all 
clogging of the valves by oil deposit, and the engine is found to 
work without trouble. As the electric spark is used in the 
Simplex engine, no difficulty is experienced in igniting the 
charge. 

S6ciirit^. — A horizontal petroleum engine patented by MM. 
Diederichs (Belmont, Chabond, and »Diederich8) and known as 
the "Security/' appeared at the Paris Exhibition of 1889. It is 
rather complicated, but is self-contained, and requires no external 
connections of any kind. Instead of an electric battery to fire 
the charge, the engine carries with it the ignition apparatus. 
This is an advantage in motors which are intended for use in 
the country, and to be handled by labourers. The " S^urit6 " 
engine may be driven with any kind of petroleum, but the best 
for use is heavy mineral oil distilled from bituminous schist, of 
0*82 to 0*85 specific gravity. It is the only petroleum engine, 
properly so called, which was shown at the Paris Exhibition. 
Like the Priestman, it is not a gas engine adapted to the use of 
petroleum by the addition of a vaporiser, but has from the first 
been intended to work with oil. 

Fig. 123 gives a general view of the engine. Two kinds of 
petroleum are used, both contained in separate compartments 
of the reservoir T. A lighter petroleum spirit is required to 
start the engine, and this is one of its drawbacks ; after it is at 
work, ordinary heavy petroleum is used. A is the horizontal 
motor cylinder, and R the auxiliary shaft, worked from the crank 
shaft by bevel wheels 2 to 1. The engine stands on a strong 
foundation, B, which is hollow, and part serves as a reservoir 
for the compressed air. The shaft R works the ignition, admis- 
sion, and exhaust valves by two cams and crank levers. One 
lever opens the admission valve under the cylinder as shown. 
The centrifugal governor G is also worked from R by means of 
bevel wheels, and regulates the admission of oil to the vaporiser 
by acting upon a cock, r, in the oil pipe. The petroleum for work- 
ing the engine is contained in the front part of the reservoir T. 
From hence it passes through a small pipe, p, and the cock r to the 
vaporiser Y beneath the cylinder, in which is a coil of pipes. 
The exhaust gases pass into the vaporiser at E, and heat the 
petroleum, which in its passage through the coil becomes com- 
pletely vaporised. It is then led out through a nozzle at the 
bottom, and injected into a pipe, F, leading to the admission valve 
of the cylinder. As it is already at high pressure and temper- 
ature, the suction of the oil spray jet draws in with it a current 
of atmospheric air from below the vaporiser at N, and the two 
become thoroughly mixed as they pass on to the cylinder. If 
the speed be too great, the balls of the governor rise^ and act upon 
the pipe p, closing the cock r. No oU enters the vaporiser, and 

21 



322 



PETROLEUH BKGINE8. 



consequently only fresh air is drawn into the cylinder by the 
next out stroke of the piston. 

The ignition apparatus is somewhat complicated, but has the 
advantage of requiring no battery, or gas to heat the tube. 
Petroleum essence, much lighter than the oil used for driving 
the engine, is contained in the vessel U above the cylinder. At 
P is the pump immediately below the crank shaft, and driven 
from it by an eccentric, through which air is pumped by the 
pipe h into a compartment in the hollow base of the engine, B, 
and from thence through h^ to tlie vessel U. The hand pump C 



ffahr 



IPhUr 




Fig. I23.~Moteur S^curitd— External View. 

is used to compress the air into the reservoir when starting the 
engine. The pressure of this air in the vessel U forces the 
petroleum essence along the pipe c, past the cock Cj adjustable 
by hand, and it falls drop by drop into a current of compressed 
air conveyed in the branch pipe d from the air pipe by The two 
are carried through pipe d^ into the compression space M at the 
back of the motor cylinder A. Before reaching the burner, the 
highly inflammable carburetted air is heated by passing it 
through a small coil of pipes, rfo, kept at a high temperature by 
the heat from the cylinder. The burner consists of a small 
platinum capsule maintained at a red heat by a carburetted air 
flame. The charge in the cylinder, compressed by the back 



BAQOT OIL ENGINE. 323 

Stroke of the piston, is ignited on reaching the capsule, and 
explosion and expansion follow. Communication is established 
between the cylinder and the igniting chamber M by a plug 
worked from the side shaft, which uncovers the small passage 
between them at every other revolution. The cylinder is kept 
cool by a water circulating jacket, as shown in the sketch. The 
consumption of oil is said to be about 1 pint per H.P. per hour. 
Bagot. — Another oil engine shown at the Paris Exhibition 




124.— Ragot £ngin&— External View. 



of 1889 waa the Belgian "Moteur Ragot," the only engine 
competing with the "S^curite." It was originally intended, 
like most other oil engines, to be driven by gas, and the vapor- 
iser added by the inventor, for petroleum where gas is not 
available. The Eagot engine is small and simple, both in its 



324 PETROLEUM ENGINES. 

method of ignition and of vaporising the oil. It uses heavy 
petroleum, having a density of 0*800 to 0*820, and the con- 
sumption of oil is said to be only about f pint per H.P. per 
hour. Fig. 124 shows a view of this compact little vertical 
engine. The crank and motor shaft are at the top of the cylinder, 
and the piston works on to them through a connecting-rod ; the 
oil vaporiser and pulveriser are seen below the cylinder. Upon 
the motor shaft is a small pinion wheel and pulley. The pulley 
works the centrifugal governor; the wheel gears into another, 
below it, of twice the diameter, from which the admission and 
ignition valves are worked by means of cams and levers, as 
shown in the drawing. The ordinary four-cycle is used, and 
there is an explosion every other revolution. The charge is 
fired electrically, and the cylinder cooled by a water jacket in 
the usual way. The chief peculiarity of the engine is the 
vaporiser, consisting of two hollow cones, of different propor- 
tions, fitting one over the other, with a space between them. 
Into this space the oil is dropped from a small receiver, com- 
municating through a pipe with an injector or nozzle. The 
suction of the motor piston draws a small quantity of air into 
the nozzle, with the oil, and the two fall together into the space 
between the cones. Here the oil is pulverised and the air 
heated. The gases of combustion are admitted from the motor 
cylinder into the inner cone, and by their heat convert the oil 
above into vapour. Through a small pipe establishing communi- 
cation between the cone and the cylinder, the oil spray and air 
are drawn, by the slight vacuum produced by the out stroke, 
into the mixing chamber, where the oil is further vaporised, 
and diluted with fresh air to render it explosive. The exhaust 
gases are also carried round this chamber before passing to the 
atmosphere. The charge is compressed by the return stroke of 
the piston in the ordinary way, and fired by an electric battery. 
The admission valve is controlled by the governor, and the 
strength of the charge, not the number of explosions, varies 
according to the speed. In the semicircular space below the 
vaporiser a lamp, fed with ordinary petroleum, is placed to heat 
it when starting, and in from 10 to 15 minutes the engine begins 
to work. The process can be quickened by introducing a few 
drops of petroleum essence or gazolene into the vaporiser. The 
" Albert ' petroleum motor, made by Messrs. Glover <k Hobson, 
is a reproduction of the " Ragot." Although handy and compact^ 
this little motor does not seem to have been very successful. 

Tenting. — A few other French engines are arranged to work 
with petroleum, where lighting gas cannot be had. In the Tenting 
engine, described in the gas engine section at p. 157, a carburator 
of the simplest description is added to the ordinary motor. It is a 
cylindrical vertical reservoir divided horizontally into three parts; 
the volatile hydrocarbons are stored in the upper, and are thence 



OTHER OIL ENGINES. 325 

supplied to the second chamber below it, which forms the car- 
burator itself. Enough liquid can be carried in this reservoir for 
an ordinary day*8 work. The products of combustion from the 
cylinder are led through the lowest division, warm the carburator, 
and counteract the cold produced by the evaporation of the 
hydrocarbon liquid. The Tenting carburator is a good example 
of the method of carburating air by bringing it in contact with 
light hydrocarbon, without the application of much heat. Air, 
drawn in by the out stroke of the piston, is passed over the 
surface of the liquid in the central chamber. It enters on one 
side, and is -carried off from the other to the cylinder, charged 
with the volatile petroleum essence. 

Durand. — In the Durand engine the vaporisation of the oil 
is effected on a different principle to that usually adopted in 
petroleum motors. As a rule, the oil is sprayed by dividing it 
up with the injection of air, and evaporating it by great heat, 
the aim being, if possible, to convert the whole into vapour, 
without any residuum. M. Durand uses only the light volatile 
constituents of the oil, the heavy hydrocarbons are allowed to 
accumulate at the bottom of the carburator, withdrawn and 
wasted. He thinks there is a gain in power and smooth working 
by this method, and these advantages more than compensate for 
slightly increased consumption of oil. The Durand carburator 
is fixed above the cylinder, the heat from which counteracts the 
cold produced by evaporation. By this arrangement the car- 
buretted air descends only, and does not lose its inflammable 
properties, as it has been found to do when ascending. Air is 
drawn into the carburator through a vertical tube, the bottom 
of which is below the level of the hydrocarbon liquid. It rises 
through a spongy mass on the top of the liquid, always saturated 
with hydrocarbon. Thus charged, the air is carried off through 
a pipe to the distributing chamber, where it is further mixed 
with fresh air to form the charge. The opening of the valve 
admitting the oil vapour to the chamber is regulated by the 
governor, according to the speed. Electric ignition is used; 
contact is interrupted and the spark produced by a rotating 
disc, worked from the auxiliary shaft (see p. 72). 

Forest. — M. Forest of Paris has lately turned his attention 
specially to small marine engines working with petroleum, and 
in conjunction with M. Gallice has produced several motors, 
which have attracted the attention of the French Government. 
One of their engines, of 30 H.P. with six cylinders, bought by the 
French Admiralty, was tested at Brest in 1890. Details of the 
trial will be found in the table at p. 404. A carburator on the 
Pieplu system is used, with light hydrocarbon. The surface of 
the petroleum is agitated by a rotating cylindrical brush. The 
air is drawn in by suction, and the petroleum being sprayed into 
it by the brush, it becomes charged with the evaporated liquid. 



326 PETROLEUM ENGINES. 

The special feature of these Forest motors is that they are re- 
versible, rapidly started, and that the direction of the engine can 
be instantly changed. The marine motors have two or more 
vertical cylinders working downwards on the crank shaft. A 
distributing shaft, from which all the ignition and exhaust 
valves are driven, runs above the cylinders. This shaft has a 
double set of cams, one for working the boat forward, the other 
for reversing the direction, and by slightly shifting the position 
of the cam to the right or left, one or the other set can be brought 
into play. The charge is fired electrically, and the spark is 
produced or missed, according to the movement of the distributing 
shaft. The arrangements for rapidly changing the direction by 
reversing the engine depend on the adjustment of this shaft. 
Drawings of this ingenious motor will be found in Witz. Other 
Prench engines working with petroleum are the Mire and the 
Noel, both shown at the Paris Exhibition of 1889. 

Cspitaine. — Among German motors, the Koerting can be 
used with petroleum. The Benz is also sometimes driven with 
carburetted air, and the charge fired by electricity. A more 
important engine is the vertical Capitaine, described at p. 187. 
It has already been about four years at work, and was one 
of the first motors to use common petroleum. It has been 
introduced into England, and a launch driven by a Capitaine 
oil engine, fitted with friction cones and bevel gearing, was tested 
at Chester in December, 1891. By means of a handle attached 
to the gearing, the motion of the boat could be reversed or sus- 
pended. This launch was 35 feet long by 6 feet 10 inches, and 
carried fifty passengers. The 6 J H.P. engine made 240 revolu- 
tions per minute ; the boat went at 8 J knots an hour. About 
twenty-five of these little boats are at work in Hambui*g, and 
many are used in other parts of Germany. The manufacturers 
state that over 1,000 engines have within twelve months been 
made for Germany and Russia. 

Like the gas engine of the same name, the Capitaine petroleum 
motor differs in one or two respects from others, and especially 
in the stratification of the charge. In both engines the same 
cycle and method of construction have been adhered to. The 
diameter of the water-jacketed cylinder is larger than in the 
usual type of motor, and the stroke shorter. The admission 
ports are so designed that the charge enters at a high pressure, 
and is rapidly expanded. The compression chamber is conical, 
and where it joins the cylinder it is of the same diameter. 
The ignition port is so arranged that part of the charge enters 
the tube at the moment of ignition, and is fired without a timing 
valve. In both the gas and oil engines the exhaust valve is 
worked by an eccentric on the crank shaft, and in the petroleum 
motor this eccentric also drives the oil pump, which is on the 
other side of the cylinder. As tlie four-cycle is used, with an 



CAPITAINE OIL ENGINE. 327 

explosion every second revolution, an alternating mechanism is 
employed to throw tlie levers operating the exhaust and oil 
pumps out of gear, and cause them to miss the valves at every 
second stroke. The governor is carried on the flywheel, and 
revolves horizontally. If the speed be too great the governor 
balls fly out, the bell crank operating the exhaust is caught, 
and the valve held open, while at the same time the rod working 
the oil pump is maintained in its highest position. No oil is 
admitted, and all the valves are at rest until the speed is reduced. 
Above the ignition tube, at the opposite side of the cylinder to 
the exhaust, we have in the Capitaine oil engine a vaporiser. 
The valves D and S (Fig. 93, p. 188) are retained at the to)», 
but they admit air only, to mingle with and dilute the already 
vaporised charge. TJie oil enters the suction of the oil pump 
by gravity ; it is then forced upwards by the small piston driven 
by the eccentric working the exhaust into the vaporiser, which 
occupies the same position as the ignition tube B, Fig. 93. The 
vajx>riser is a small horizontal iron tube, maintained at a red 
heat by a lamp below. This lamp is provided with a long bent 
tube, at the end of which is a conical burner; the flame of the 
burner not only evaporates the oil in the vaporiser, but in the 
tube. Being bent, the oil in it is exi)osed to greater heat from 
the flame. In the earlier oil engines, the flame also played upon 
the small ignition tube. Firing by tube has recently been dis- 
carded, and the heat of the vaporiser alone is found sufficient 
to ignite the charge, after its compression by the piston. Unlike 
the arrangement usually adopted in oil engines, the heat of the 
exhaust gases is not utilised to vaporise the oil. 

On entering the vaporiser, the oil is met by a small current 
of air, drawn in at the same time, at right angles to the oil, by 
the down stroke. As the oil pump injects only a minute quan- 
tity of oil at each stroke, it is instantly vaporised by the heat, 
and passes on to the cylinder. The air continues to enter, and 
thus a cushion of highly inflammable oil vapour is formed next the 
piston, and behind it probably a cushion of hot air only. At 
the same time the suction stroke lifts the valves, and air enters 
through the admission valve at the top of the cylinder (as in 
Pig. 93) J the charge is diluted, the next compression stroke of 
the piston forces it back into the vaporiser, where it is ignited 
and fires the charge. These two currents of air are said to form 
a non-inflammable layer, and to prevent the oil vapour in front 
from communicating with the red-hot vaporiser, until the return 
stroke of the piston. The air drawn into the vaporiser by the 
suction of the piston, drives before it the inflammable oil vapour 
into the cylinder. Herr Capitaine maintains that all the heat 
is employed to vaporise and ignite the charge, and both vapor- 
isation and combustion are therefore more complete. Owing to 
the stratification of the oil vapour and air, the top of the piston 



328 PETROLEUM ENGINES. 

is hotter than the bottom, heat is imparted to the charge during 
its expansion, and raises the pressure curve. The indicator 
diagrams are said to confirm this theory. The consumption of 
oil claimed for the Gapitaine engine varies from 1 pint per B.H.P. 
with 1 H.P. engines, to 7 pint per B.H.P. per hour with engines 
of 4 H.P. and upwards. It is maintained that premature igni- 
tion is impossible, and that the engine, on account of the great 
heat of the vaporiser, and therefore of the charge, works with- 
out any deposit of carbon. A drawing of the Gapitaine oil 
engine, with indicator diagrams, will be found in Engineering^ 
January 1, 1892. 

Daimler. — The Daimler petroleum motor differs in some 
respects from the gas engine of the same name described at 
p. 178. It has already been successfully employed for driving 
small boats, and has been fitted in about 480 launches ; a 37 feet 
launch driven by a 10 H.P. Daimler oil motor was recently 
supplied to the London Gounty Council. The author was lately 
permitted to inspect one of these little petroleum launches on 
the Thames. It ran quietly, with no smoke, and no perceptible 
smell, was easily steered, the direction reversed, or the boat 
stopped at a moment's notice. The speed varies from 8 to 10 or 
11 miles an hour. More than fifty boats equipped with these 
motors are in use in Hamburg, and they have also been applied 
for driving fire engines. 

As in the gas engine, the Daimler petroleum motor has 
two single-acting cylinders, the pistons of which are set at 
an angle of 180*, and worJc upon the same crank shaft, but 
they have no valves. Fig. 125 shows the arrangement of the 
parts. In the oil receiver or vaporiser A (which is previously 
filled with petroleum), vapours are generated by means of the 
suction of heated air through the oil. The tube conveying this 
hot air to the top of the vaporiser is surrounded with a jacket, 
through which the products of combustion are led on their way 
to the open air. The oil vapour and air then pass to the regu- 
lating valve H, where more air is added to dilute them in proper 
proportions. They are next conveyed to the cylinder, entering 
through an automatic lift valve, as in the gas motor. The back 
stroke of the piston compresses the charge in the usual way. 
Ignition is effected by means of two small lamps, L, one for each 
cylinder. These lamps are fed from the receiver B, to which oil 
is supplied fix)m the reservoir R, and the valve cock ;;. The 
passage of the oil to the lamp is regulated by means of the valve 
V, and the lamps burn with a clear blue flame. Within them 
are fixed two very small platinum tubes b, kept at a white heat, 
which fire the charge in either cylinder automatically, without a 
timing valve, at the end of the compression stroke. Upon the 
proper burning of these two little lamps, the efficient working of 
the engine in great measure depends. The same passage serves 



OTHER OIL ENGINES. 



329 



to admit the fresh charge to the cylinder, and to carry off the 
gases of combustion ; the exhaust valve rod is worked from the 
crank shaft by wheels 2 to 1. The governor on the flywheel 
checks the admission of the combustible gas, when the normal 
speed is exceeded. The engine works with petroleum of 0*68 
to 0*70 specific gravity, and flashing point under 73* ( Abel's 
test). Great care must therefore be exercised in handling and 




Fig. 125. — Daimler Oil Engine — Section of Cylinder and Valves. 

storing the oil. The cost of working is said by the manufac- 
turers to be about Id. per H.P. per hour. The sides and covers 
of the cylinders are cooled by water jackets. Drawings and a 
full description of the Daimler oil motor will be found in The 
Engineer, April 14, 1893. 

Adam. — The Adam petroleum engine resembles the gas motor 
of the same name, already described at p. 171, with the addition 
of a vaporiser. Benzine or naphtha are used to drive this, 
engine, and enter the generator in a liquid state from a receiver. 
The oil is here converted into gas and passes to the cylinder, 
part going to form the charge, and part to heat the ignition tube. 
During the whole process, the benzine is carefully protected from 
coming in contact with the outer air. The consumption is given 
at a little over 1 lb. of benzine per H.P. per hour. The engine 
is made in nine sizes, from ^ to 10 H.P. indicated. 



330 PBTEOLEUM ENGINES. 

The Berliner Maschinen-Bau Gesellacbafb have also brought 
out a small engine for petroleum. 

Altxnann and E'lippermann. — An oil engine made by this 
firm in Berlin is compact and simple ; the method employed for 
vaporising and igniting the oil is very practical. The engine is 
verticjil, and the piston works upwards on to the crank. Admis- 
sion, ignition, and exhaust are effected from a small auxiliary 
shaft, worked from the main shaft by two sets of conical wheels. 
The petroleum is drawn from the reservoir through a suction 
valve, and delivered by a small pump with adjustable stroke into 
the vaporiser, a shallow vessel heated by a spirit lamp below. 
The lamp is protected by a cover, and the hot ignition tube pro- 
jects into the flame. A separate receiver, into which air is com- 
pressed by an india-rubber valve, feeds the lamp. The vaporised 
oil then passes to another valve chamber, where it is diluted 
with air before entering the cylinder. Here it is exploded, and 
expands in the same way as gas, the usual Beau de Rochas four- 
cycle of operations being carried out. The oil pump and the 
suction valve admitting the oil from the reservoir are worked 
from the same lever. A cam on the auxiliary shaft lifts a roller 
on the lever once in every two revolutions, if the speed is 
regular. If the engine is running too quickly, the cam, which 
is held in position by a spring, is thrown out of gear by a smaller 
projection, and misses the roller. The lever not being lifted, no 
oil enters the cylinder until the speed is reduced. 

Iiilde- Vulcan. — A more important petroleum engine, con- 
structed by Langensiepen of Magdeburg, and designed by 
Herr v. Liide, has been tested by Professor Schottler. It is a 
horizontal four-cycle motor, self-contained, with hot-tube ignition. 
Although its advantages are somewhat counterbalanced by the 
many levers, <kc., Professor Schottler is of opinion that it is the 
arrangement of the parts, not their number, which makes the 
engine appear complicated. The admission, distribution, and 
exhaust valves are worked by cams and levers. The exhaust 
lever is acted upon by a cam on the auxiliary shaft, parallel to 
the crank shaft, and driven from it by spur wheels ; the same 
shaft works the oil pump and admission valve. The ball gover- 
nor is fixed upon the crank shaft inside the driving pulley, and 
acts by cutting out the number of explosions. If the speed be 
too great, it pushes forward a projection, which catches in the 
lever of the admission valve ; the valve is not raised, and no 
charge enters the cylinder. 

The most original parts of this engine are the methods of 
conveying the oil to the vaporiser, and the lamp. The oil 
descends by gravity from a petroleum tank above the cylinder, 
and passes through the suction valve of the oil pump, worked by 
the auxiliary shaft, which also regulates the descent of the little 
plunger piston. The stroke of the pump is always the same, and 



AMERICAN ENGINES. 831 

delivers an equal quantity of oil, but the pump communicates 
with two delivery valves and pipes. One opens a passage back 
to the oil reservoir above. The other has a nozzle attached, 
through which a certain quantity of oil is injected, at every 
stroke of the oil pump, into the air valve. Air enters at the 
same time, the valve being worked by the same lever. The 
proportions of oil sent on to the vaporiser and motor cylinder, 
and returned to the reservoir, are determined by the adjustment 
of a screw in the plunger of the oil pump; the stroke is regulated 
by moving a handle. The oil being sprayed into the air, the two 
pass into the vaporising chamber below, communicating with 
the cylinder. At starting, this chamber is heated by a lamp fed 
from a second reservoir of petroleum spirit. As soon as the 
engine is at work, the heat generated by the explosions is 
sufficient to keep the vaporiser at a suitable temperature; the 
lamp on its stand is then drawn back a little, and serves to heat 
an ignition tube of the ordinary type, connected to the vaporiser. 
The lamp consists of a coil of pipes, in which the petroleum is 
converted into gas by the heat of the flame ; the amount of oil 
passing into it at a time is regulated by a screw valve, and it is 
said to bum with very little carbon deposit. The engine runs 
at a high speed, making in the small 1^ H.P. motors 600 revolu- 
tions per minute. In the motor testeid by Professor Schottler, 
the mean speed was 325 revolutions per minute. The engine 
indicated 6*7 H.P., and the consumption of petroleum, not 
including the lamp (which requires J pint per hour), was ^ pint 
per H.P. per hour. The specific gravity of the oil used in the 
trial was 0*828. Like most engines in which the oil is gasified 
in a separate vaporiser, the parts have to be lubricated in the 
ordinary way. 

The same engine is made by G. Kiihn of Stuttgardt, under 
the name of the " Vulcan." It was shown at the Frankfort 
Exhibition of 1891, and the author saw it working well at the 
high speeds given. The consumption of oil varies, according 
to the makers, from I'l lb. for engines of 1 to 2 H.P., to about 
I lb. in engines of 5^ to 6^ H.P. These two last engines are 
fully illustrated in Zeitschrifi des Vereines deutscher Ingenieure^ 
August 29, 1891. 

An oil engine has been recently patented by Brunler, of 
Leipzig, having three cylinders and pistons revolving round the 
crank. Air, into which a jet of petroleum is injected, is drawn 
into the cylinders at each stroke; the petroleum is previously 
vaporised in a separate chamber. 

AMERICAN ENGINES. 

Caldwell. — The Caldwell-Charter engine, made by Messrs. 
H. W. Caldwell & Son, Chicago, is intended to be driven with 



332 PBTROLBUM ENGINES. 

either gas or petroleum. In the latter case the oil is drawn 
from a reservoir in the base, and forced by a small pump, close 
to and worked from the crank shaft, into a brass pan, where it is 
mixed with air in the proper proportions. The air is drawn in 
through two pipes, and the admission regulated by the governor 
on the crank shaft. The engine works with the ordinary four- 
cycle, has a ^ater jacket, and ignition by a hot tube heated by 
a small gazolene burner. A 95 I.H.P. engine is running at 
Camden, United States. 

Fogs. — Another American engine, working with either gas 
or light petroleum spirit (gazolene), is made by the Foos Gas 
Engine Company, Springfield, Ohio. The motor is fired electri- 
cally, the connection and separation of the electrodes being 
effected from the main shaft through gear wheels. No attempt 
is made to vaporise the oil. It is contained in a tank at the side 
of the engine, and air, previously warmed by passing round the 
exhaust valve, is drawn by the suction stroke of the piston through 
the petroleum vapour, which it absorbs in its passage to the 
admission chamber. The engine is of the usual four-cycle type. 

Kane. — Of the same class of motor is the Kane, built by 
Messrs. Kane, of Chicago. The carburator is simply a small 
circular tank partly filled with light petroleum spirit, through 
which air is drawn, and is charged with oil vapour in its passage. 
No heat is applied to the air or oil. The engine is fitted with 
reversing gear, and has been specially adapted for marine use. 

Nash. — An engine working chiefly with gas, and not fitted 
with any carbu rating- or vaporising apparatus, is the Nash, made 
by the National Meter Co., New York. As in some other 
engines already described, the crank is enclosed to form a cham- 
ber for compressed air, and the motor resembles the Day in some 
respects, though not so simple, and has an explosion every 
revolution. The charge is compressed below the piston, and 
passed up through a passage in the side of the cylinder to the 
top, where combustion takes place. Ignition is by a flame, 
which is made to rotate in a circular chamber. 

Safety. — The SSafety Vapor Engine, made by the Company of 
that name in New York, is a small vertical gas engine of the 
usual four-cycle type, which can also be driven with gazolene. 
It has one noticeable feature. The valve for admitting the 
charge to the cylinder and expelling the burnt products is a 
circular rotatory valve, worked by a chain revolving on a pulley 
of twice the diameter of a smaller pulley on the crank shaft, 
from which it is driven. Although hitherto made only in sizes 
from ^ to 6 H.P., the engine is intended for marine use, and has 
frictional driving gear for connection to the propeller shaft. 

Van Duzen. — A more important motor, made in several 
types, stationary and portable, for both gas and petroleum, is 
built by the Van Duzen Gas and Gazolene Engine Co , of Cin- 



AMEBICAN ENGINES. 333 

cinnati. The engine is horizontal, of the four-cycle type ; the 
admission, ignition, and exhaust valves are worked by rods and 
cams on an auxiliary shaft below the crank shaft, and revolving 
at half the speed. This engine is fitted with a carburator, 
though no heat is used to vaporise the oil. Light petroleum 
spirit is contained in a chamber at the side of the engine. Air 
is drawn upwards into a vertical tube below this chamber, and 
lifts a valve, causing the oil to flow down and mingle with it, as 
it forces its way through another lift valve, and down the sides 
of the vertical carburator. The petroleum is vaporised by the 
force of the air current, as it drops through gauze rings. At 
the end of the admission stroke the flow of air ceases, the valves 
fall back on their seats, and the supply of oil is cut off. Hot 
tube ignition is used, and above the chimney protecting the 
tube is a ball, which is said to act as a cushion, and disperse the 
waste products in the ignition tube. This engine is especially 
adapted for portable motors. 

SintB. — llie Sintz engine is made in sizes from 1 to 15 H.P. 
by the Sintz Gas Engine Co., of Grand Rapids, Michigan. It 
closely resembles the Day ; when intended to be driven by oil a 
small pump is added, which injects a fine spray of light petroleum 
into the compressed air, as it passes from the enclosed crank 
chamber to the upper part of the cylinder. 

Hioks. — The only noticeable feature of the twin -cylinder 
Hicks gas engine, made at the works of that name, Cleveland, 
U.S., is that the two cylinders are placed vertically one above 
the other, and are supported on the same frame. In other 
respects the engine follows the usual four-cycle series of opera- 
tions, but having two cylinders, an explosion in one or the other 
is obtained at every revolution. 

Hartig. — A small vertical engine, in sizes from ^ to 8 H.P., 
is made by the Hartig Gas Engine Co., Brooklyn, New York. 
It is worked with gas only, and does not appear to have been 
adapted for petroleum. The usual four-cycle is employed. There 
are four valves — the governor, admission, ignition, and exhaust. 
The admission of the gas and air is automatic ; the other valves 
are driven by rods, cams, and gear wheels from the crank shaft. 

Tniflty. — The Trusty oil engine has been taken up by Messrs. 
Connelly, of the Connelly Motor Co., and especially adapted for 
use on tramways. Several of the Chicago lines are worked with 
it, and it is largely used in the United States. The engine is 
the same as that already described at p. 312, but it is fitted with 
mechanism for varying the contact pressure on the rails, giving 
the maximum on a curve or when starting the engine, and the 
minimum when running at full speed. The motor is also made 
to travel in either direction. The charge is fired electrically. 
There are two cylinders, and an impulse every revolution is 
obtained from them alternately. The motor now used (1893) to 



334 PETROLEUM ENGINES. 

drive a tramway in London is of 12 actual H.P., and runs at a 
maximum speed of 12 miles an hour, at a cost of about 24d. 
per engine mile. It carries with it sufficient oil for a day's run. 
It is described with drawings in Tlis Engineer, September 30, 
1892. 

Pacific. — An engine using the ordinary four-cycle, with 
electric ignition, and in which the motive power is derived from 
either gas or gazolene, is the Pacific, made by the Union Gas 
Engine Co., of San Francisco, and the Globe Gas Engine Co., of 
Philadelphia. It is especially adapted for marine use, fitted with 
reversing gear, and has a clutch lever for starting and stopping 
the propeller shaft. Water for the cooling jacket is drawn from 
and returned to the water round the boat. The engine itself is 
never reversed, but only the direction of motion of the propeller 
and secondary engine shafts. The exhaust valve is raised once 
in every two revolutions by a double-grooved cam on the crank 
shaft, into which a projection fits, after the same manner as in 
the Daimler engine. The governor acts on the exhaust valve, 
and holds it open if the normal speed be exceeded. The vapor- 
isation of the oil is efiected as in the Van Duzen engine. Air, 
previously heated by the exhaust gases, is drawn upwards by 
the suction stroke of the motor piston into the vaporiser, a glass 
or metal chamber, above which is a tank containing light petro- 
leum or gazolene. The current of air lifts a valve, and a small 
quantity of gazolene flows into the vaporiser, where it is said to 
be instantly turned into oil vapour by the hot air. The engine 
is vertical, and is made with two cylinders for larger powers. 

Union. — In the Union horizontal engine, built by the same 
Company, the charge is also fired electrically, contact being made 
and interrupted between two electric wires by projections carried 
on the ignition and exhaust valve rods. The usual four-cycle is 
employed, and the valves are acted upon by cams from an auxili- 
ary shaft. A weight governor is carried on the crank shafts and 
if the speed is too great, the exhaust valve is held open, and at 
the same time the admission valve closed by a small beam. Only 
stationary engines of this type have hitherto been made.* 



NOTE ON THE OIL INDUSTRY IN THE CASPIAN REGION. 

{From Marvin's ** Hegim of Eternal Fire.") 

Until 1872 the oil industry at Baku was a monopoly of the Crown of 
Russia, farmed out to a merchant named Meerzoeff. The European market 
was flooded with American oil, which was exclusively used, even in Russia, 
and it was to encourage the home trade that the Russian Government were 

* Most of these particulars of American oil engines have been taken from 
a series of papers by Mr. Albert Spies. 



OIL INDUSTRY. 



335 



induced to put an end to the monopoly. At that time there were 417 wells, 
with an annual output of 24,800 tons of oil, and the price of petroleum was 
£3, lOs. per ton. An excise duty was imposed until 1877, since which date 
there has been no tax or check upon tne development of the petroleum 
industry. The first oil fountain was '* struck " in 1873, and the abundant 
and continually increasing supply has reduced the price from forty-five 
kopecks to five kopecks per pood. The number of drilled wells increased 
from 1 in 1871 to 400 in 1883, and the production of refined oil from 16,400 
tons in 1872 to 206,000 tons in 1883. The price of land in the oil district 
round Baku has also risen enormously, and in 1884 it varied from lOs. to 
£2 per square sajene = 7 feet square. The specific gravity of the crude oil 
is about 0*822 ; it yields 27 per cent, of kerosene or ordmary lighting oil, 
having a flashing point of 36" C. 

RoMrt Nobel, a Swedish engineer, started his first oil refinery at Baku 
in 1875, and was soon joined by his brother Ludwig, who assumed the 
principal direction of affairs. The Nobels were the first to lay down a pipe 
une, at a cost of £10,000, instead of conveying the oil in carts to the 
distilleries, and the outlay was covered in the first year. There are now 
seven pipe lines, two belonging to Nobel Brothers, three to private Russian 
firms, and two to companies ; 161 million gallons of oil are thus conveyed 
yearly to the refineries. Beinjy^ foreigners, the Nobels had from the first to 
struggle with severe competition from the Russian firms, and after laying 
down their pipe line were next obliged to build their own steamers to 
receive the oil. The first oil or *' cistern steamer" was constructed in the 
Nobel shipbuilding yard at St. Petersburg, and appeared on the Caspian 
in 1879. The firm have now a regular fleet of vessels, each holding about 
750 tons of kerosene, as well as twelve smaller distributing ships on the 
Volga. They have also established a system of tank cars on all the 
Russian railways, and possess twenty -seven oil dep6ts at various chief 
towns in Russia. More than fifty-four million gallons are sold by them 
yearly, and they have over forty wells, one of which yielded, in 1882, 
112,000 gallons of crude oil. The following table shows the output and 
price of petroleum from 1873 (the year after the monopoly was taken off) 
to 1883 :— 



Year. 


Ontpat. 


Price per Ton at Baku. 




Ton,. 


«. 


d. 


1873 (monopoly abolished), . 


64,000 


7 


9 


1874, 


78,000 


6 


3 


1876, 


94,000 


15 


6 


1876, 


194,000 


7 


9 


1877 (excise duty taken off). 


242,000 


12 


6 


1878, >! /^ . . 


320,000 


8 


8 


1879, 


' 


370,000 


6 


3 


1880, 
1881, 


^ Nobel Period, ^ • 


420,000 
490,000 


3 
2 


8 
6 


1882, 


. . 


680,000 


2 


6 


1883, ; I . . 


800,000 


2/6to6d. 


& lower. 



PAET III. 



AIR ENGINES. 

Contents. — Theory — Cay ley — Buckett— StirUng's First Engine — Stirling's 
Second Engine — Robinson — Ericsson — Wenham — fiuley — Rider— 
Jenkin's Regenerative Engine— Bonier— DieseL 

Theory. — In dealing with oil engines, no mention has been made 
of the theory of heat motors, and of their theoretical and actual 
heat efficiencies, <fec., because in these respects oil and gas engines 
are based on the same principles. The effects of an explosion of 
coal gas with air, or oil vapour with air, when mixed in the 
cylinder of an engine, are similar, and the temperatures, from 
which the heat efficiencies are calculated, are the same. When we 
consider hot air engines, the conditions are different. There is 
no explosion, and no great rise or fall of temperature. A certain 
quantity of heat is applied to air, which expands and drives 
a piston, doing work. No boiler is needed, nor is any cost 
incurred for gas or oil from a tank, the air as working agent 
being taken from the surrounding atmosphere. There is no risk 
of explosion from inflammable gas or oil vapour. No change of 
physical state in the working agent takes place, and therefore 
all the heat generated and imparted to the air can, in theory, 
be utilised in work. The two main sources of waste of heat 
in gas engines are the cooling water jacket and the exhaust. 
In a hot-air motor there is no jacket (unless as a refrigerator), 
and therefore less heat should be dissipated, and more available 
for work. From these considerations, therefore, it seems as 
though a hot air engine must be not only better in theory, but 
more economical in practice, than other forms of heat motor. 

Such, however, is not the case. Practically, hot air engines 
do not give results as satisfactory as might have been expected. 
Though the first engine of this type was designed in 1807, com- 
paratively few have since been made, and their construction has 
not been much developed, except for special purposes. The 
reason for this neglect may probably be found in their low actual 
efficiency — that is, the amount of heat they turn into work. In 
theory the whole of the heat furnished to the air being utilised 
in expansion, a high ratio of efficiency should be obtained. 

22 



338 AIB ENGINES. 

Practically expansion cannot be continued to the pressure of 
the atmosphere, and therefore some heat remains in the air, 
and is wasted at exhaust. The theoretical heat efficiency of 
an engine depends upon the range of temperature — that is, 
its highest and lowest working temperatures. But if heat 
be added to the air up to 900" F., and if the temperature of 
exhaust is 600' F., only the difference, or 300", will be spent 
in expansion, and heat equivalent to 600" will be wasted. As 
in gas motors, the difficulty consists in utilising the expansive 
force of the agent, or air. Since expansion cannot be unlimited^ 
only a certain proportion of the heat imparted can be turned 
to account as work. If it were possible by expansion to reduce 
the air in a hot air engine to the temperature it had before 
entering the cylinder, an efficiency of about 59 per cent, 
might, according to Professor Jenkin, be realised ;• the actual 
heat efficiency, or percentage of work to total heat received 
in these engines, is only from 7 to 10 per cent., not very 
different from that obtained in steam engines. The Stirling 
engine worked between the temperatures 343* 0. and 65" C. 
The theoretical efficiency, according to the formula at p. 216, was 
Ti-To 343" -65" 278 ,- ^ rru ^ i 

-T->^" 343" + 273"(abs.) ^4T6P^)°^^^ Theactual 

efficiency (see p. 344) was 7 per cent. 

Difficulties of Hot air Engines. — To increase the efficiency 
and check the source of waste in these engines —that is, the high 
temperature of the exhaust, — the only method would appear to 
be to increase the ratio of expansion, and this can only be done 
by raising the initial compression of the air. But this does not 
produce any real advantage, because the pressure which is ex- 
pended must be deducted from the pressure exerted upon the 
piston. To compress the air before it is admitted to the cylinder 
requires a certain amount of negative work, pr work done on the 
working agent. The further compression is carried the greater 
the proportion of negative work, and the lower the proportion of 
positive work, or work done by the air. If the air be compressed 
to 100 lbs., C5 per cent, of the work would be required in theory 
to obtain this compression. It is also difficult to prevent leakages 
where high pressures of air are used. To keep all the parts 
of the engine perfectly air-tight is almost impossible, while to 
obtain an efficient working pressure it is necessary to use & 
large body of air. Air is a very bad conductor and does not 
absorb heat readily, and it expands in comparison with its bulk 
much more slowly than steam. In the Ericsson air engine, the 
pressure was only 3 lbs. per square inch. 

Hot air engines are therefore bulky, and seldom suitable to 
replace steam or gas. Their special advantages are — 1. Ease 
in working. 2. Absolute safety. For these reasons they are 
generally employed for driving fog signals on lightships, light- 



BUCKETT AIR ENGINE. 



339 



bouses, and in other isolated places, where these advantages 
outweigh the defects. They are also used for domestic and 
other purposes, namely, pumping, sawing, printing, driving 
tools, &c. 

Cayley-Buokett. — The earliest hot air or caloric engine was 
introduced by Sir George Oayley in 1807, and patented by him 
in 1837. The original design has been adopted by Mr. Buckett, 
and practically the same engine is now made by the Caloric 
Engine Company. Fig. 126 gives a modified view of the Cayley- 
Buckett Caloric engine. It consists of two distinct parts, like the 
boiler and motor cylinder of a steam engine. A is the working 




Fig. 126.— Buckett Hot Air Engine— Single Cylinder. 



cylinder containing the piston P, B is the furnace in which 
the air is heated. Above the motor cylinder is a second pump 
cylinder J, into which air is admitted through the valve M, 
and compressed by the action of the piston Pj. The two pistons 
are connected to each other, and the up expansion stroke of the 
one forms the compression stroke of the other. The air, after 
being compressed in J, passes through the valve I and down the 
passage c? in the direction of the arrows, till it reaches a cylindrical 
valve c, directly controlled by the governor G above it. Here 
the current of compressed air is divided. Part of it passes down 
the passage ^, between the fire-brick lining W of the furnace and 
the outer casing, and is admitted through holes at the bottom of 



340 AIR ENGINES. 

the grate to the furnace B, where it stimulates combustion. The 
rest passes through the upper part of the valve, enters above 
the furnace at J\ as shown by the arrows, and mingling with 
the products of combustion, prevents the escape of unbumt 
carbon. From here the hot air and products are carried off 
through the passage h into the motor cylinder, where by expan- 
sion they drive up the piston P. They are admitted through a 
lift valve V which, as well as the exhaust valve E on the opposite 
side of the cylinder, is driven by valve-rods, levers, and cams 
from the crank shaft K. Coal is fed into the furnace through the 
hopper H and the door D. During this time the valve R closes the 
top, to maintain the air pressure in the furnace during stoking. 
By opening the cock at r a portion of the hot air enters the hopper, 
and the pressure is equalised. As soon as D is closed, K is 
lowered into the furnace by the chain «. Combustion is regulated 
by passing more air, either under the furnace at ^, or over it 9Xf. 
If the speed is too great, the governor acts upon the cylindrical 
valve, and checks combustion by forcing the greater part of the 
air to mingle with the products of combustion from the fire. 
The Cayley-Buckett engine has no regenerator, but by an 
ingenious arrangement the cold air, after being compressed in J, 
is led round the valve Y, admitting the hot air and gases to the 
motor cylinder. Thus the valve is kept cool, and the fresh charge 
of air heated on its way to the furnace. The air being exhausted 
at each stroke, a closed cycle cannot be obtained. 

Trials. — In a trial on a 12 H P. nom. double-cylinder vertical 
Buckett engine, the difficulties of this class of motor were well 
shown. The gross I.H.P. was 41*24 and the pump I.H.P. 21-04. 
Thus more than half the power was employed in negative 

work, leaving only 20*2 
-9oih». H.P. for working the 

engine. The B.H.P. 

'**• was 14-39, and me- 

-loxbt, chanical efficiency only 

7 1 per cent. The mean 

Mi;^, j,r.«„7v«.../.^i/A*. ^ pressure on the pistons 

Fig. 127.--Biickett Hot Air Engine- ^jis 18-5 lbs., on the 

Indicator Diagram. pumps 16-/ 8 lbs. per 

square inch. The coke 
consumption was 2 54 lbs. per B.H.P. per hour, and only about 
8 per cent, of the total heat supplied was turned into work. 
The engine ran at 61 revolutions per minute, the diameter of 
the working cylinders was 24 inches, of the pumps 18 inches, 
stroke 16 inches. Fig. 127 gives an indicator diagram of the 
engine. A motor similar to the Cayley-Buckett was described 
with illustrations in Engineering in 1887. 

Stirling. — The first application of the principle of the re- 
generator to heat engines is due to Robert Stirling, a Scotch 




STIRLING AIR KNGINE. 341 

minister, who, with his brother James Stirling, an engineer, took 
out several patents for heat motors, the first dating from 1 827. 
Stirling's double merits as an inventor have not until lately 
received sufficient recognition from scientific men, perhaps 
because he was, like many other pioneera, in advance of his 
time. He first endeavoured to carry into practice the principle 
of a perfect heat engine (Camot's cycle), and he also designed 
the regenerator. In a perfect heat motor the same quantity of 
heat is imparted to and withdrawn from the working agent, so 
that at the close of the cycle it returns to its original state, and 
the series of operations may be reversed. Robert Stirling 
obtained this perfect theoretical cycle by means of the second 
great improvement he introduced, the use of a regenerator, in 
which the heat of the working agent (air) is stored as it leaves 
the cylinder, and refunded afterwards, as it returns to the 
furnace. Many scientific men are of opinion that the proper 
development of the principle of the regenerator affords the chief 
possibility of improving the working cycle of heat motors. The 
regenerator has been ingeniously called a " filter," because both 
the hot and cold charge are " filtered," or passed through it at 
their highest and lowest temperatures. It is intended to 
diminish as far as possible the waste of heat at exhaust. 
It acts by arresting and storing the heat remaining in the 
working fluid after expansion, instead of allowing it to escape 
to the atmosphere, and gives back this heat to the next charge 
in its passage to the cylinder. The result is obtained in this 
case by making the hot gases pass through thin metal plates, 
wire gauze, or other heat-absorbing substances, to which they 
give up their heat, and ctirrying the cold charge back through 
the same metal to receive heat from it. 

Stirling's First Engine. — Stirling took out two patents for 
hot air engines working with a regenerator. In the first, dated 
1827, he proposed to have a motor cylinder and piston, an air 
pump and two hot air vessels. The vertical motor cylinder and air 
pump were attached to a horizontal beam driving the crank ; an 
eccentric and parallel motion worked the pistons of the air vessels 
through a balance beam. Each of these air vessels or cylinders 
contained a plunger piston composed of thin metal plates forming 
the regenerator. A furnace being lighted beneath the cylinders, 
air, compressed by the air pump into a receiver in the base, was 
admitted at the bottom to start the engine, and to supply the 
loss by leakage. By its expansion it drove up the motor piston, 
and in its passage through the plungers gave some of its heat to 
the regenerator. The cylinder covers of the air vessels were 
kept cold, and the air on reaching the top became immediately 
chilled. The hot air cylinders communicated, the one with the 
bottom, the other with the top of the motor piston. As the 
air decreased in temperature its pressure fell, and both the motor 



342 



AIB ENGIKB8. 



piston and the piston of one of the air vessels descended. At 
the same time the air in the other cylinder being heated expanded, 
and by its pressure drove down the piston of the motor cylinder. 
Each time the cold air descended, it passed through the regener- 
ator, and became heated afresh. 

In Fig. 128 a modified view of this engine is shown. A is the 
motor cylinder and P the piston, B the air or displacer cylinder, 
and D a plunger piston working in it, F the space where the 
air is heated by the fire. The plunger or displacer D is filled 
with brick-dust, or other non-combustible material. The circular 
regenerator R is round D, and consists of metal plates about 



f 




Fig. 128.— First Stirling Engine. 



-f\y inch in thickness and J^^ inch apart. E is the refrigerator at 
the top of cylinder B, and is formed of coils of copper tubes 
through which cold water circulates; the hot air from the dis- 
placer cylinder acts on the motor piston. The cycle of the 
engine is as follows : — When the displacer piston is at the top of 
cylinder B, all the air is below it in F, heated by contact with 
the fire. As the air expands, its pressure is transmitted to the 
working cylinder, and it drives up the piston P. The displacer 
piston is now driven down, and forces the air below, through 
the regenerator, into the vessel and refrigerator at the top of 



STIBLINO AIB ENGINE. 



343 



cylinder B. While the displacer is in its lowest position, the 
motor piston comes down. The air in B, which has already 
deposited the greater part of its heat in the regenerator, is 
further compressed, and passes around the refrigerator pipes E, 
where it is cooled, the heat from the furnace being shut out by 
the non-conducting material in D. By the energy of motion 
left in the flywheel, D is lifted, and beginning to rise forces 
down the cold air above it through the regenerator, where heat 
is added to it before it reaches the furnace. The motor piston P 
is driven up by its expansion, and the cycle recommences. 

Stirling's Second Engine. — In Stirling's second engine, 
introduced in 1840, Patent No. 8652, the regenerator and 
refrigerator are placed on 
one side of the cylinder. 
Fig. 129 shows the arrange- 
ment, the parts are lettered 
88 before. C is the displacer 
cylinder, D the plunger, 
F the space below it, A 
the passage leading to 
the motor cylinder. E 
is the refrigerator cooled 
by water, I the passage 
to the regenerator. The 
action of the engine is the 
same as before. There are 
one motor and two hot air 
cylinders. The air is 
delivered into the cylinder 
by a small pump at a pres- 
sure of 150 lbs. per square 
inch, and passes through 
the regenerators from one 
hot air cylinder to the 
other, driving the motor 
piston up and down in its 
passage. There is no ex- 
haust, the same air being 
used continuously, and a 
closed cycle is thus ob- 
tained. This engine pre- 
sents in a compact form the 
main principles of Stirling's 
invention, and illustrates 
better than any other type ^ig- 129.-Second Sfcirluig Engine, 
of motor the construc- 
tion of a perfect heat engine. Here we have the source of heat 
(the furnace), the source of cooling (the refrigerator), and between 




344 AIR ENGINES. 

the two the regenerator, which abstracts heat as the air passes 
to the refrigerator, and refunds it as it returns to the source of 
heat. One of Carnot's chief propositions is here put in practice. 
Heat is imparted to the working agent at its highest temper- 
ature, and withdrawn at its lowest. In both cases its tem- 
perature, previous to this addition and subtraction of heat, is 
raised and lowered by the regenerator. A perfect reversible 
heat engine was the result, but in practice it did not work well, 
and only about 7 per cent, of the total heat producecl was 
utilised as motive power. A Stirling engine was used to drive 
machinery for three years at the Dundee Foundry. It indicated 
40 H.P., had a cylinder diameter of 16 inches, and 4 feet stroke, 
and required about 2^ lbs. coal per H.P. per hour. 

Bobinson. — A small engine embodying Stirling's principles 
has been brought out by Robinson, and made by Messrs. Pearce 
& Co. of Manchester. It is very compact, with one vertical 
single-acting cylinder containing two pistons. The lower is the 
displacer and regenerator, and is filled with wire gauze, acting 
in the same way as in the Stirling engine. The section of the 
cylinder in which the displacer moves to and fro is lined with 
fire-brick, to retain the heat. In the upper part of the same 
cylinder is the working piston, and here the cylinder is sur- 
rounded by a water jacket, to serve as a refrigerator. The two 
pistons work through connecting-rods on two different cranks at 
right angles to each other; the crank of the displacer is in 
advance of the motor crank, and the displacer-rod works through 
a stuffing box in the motor piston. Instead of a grate and coal, 
in which much heat is dissipated, the temperature of the work- 
ing agent is raised by a Bunsen burner, fed with air heated by 
passing through a jacket outside the chimney carrying off the 
products of combustion. When the displacer piston is at the 
top of its stroke, all the air below it is heated by the burner, 
expands, and drives up the motor piston. As the displacer 
comes down, it forces the air to pass through the regenerator 
into the space above, between the two pistons. Some of its heat 
has already been carried off by the regenerator, and it is here 
further cooled by contact with the cold water jacket of the 
refrigerator. The pressure falls, and the working piston descends. 
The displacer now rises, and the cold air is forced down through 
the regenerator. In its passage it regains the heat it had parted 
with, before it reaches the hot plate above the Bunsen burner, 
where it is heated afresh, and the cycle repeated. In this 
engine the only cost is the supply of gas to the burner, which 
is about Jd. an hour for a 1-nian power engine. The air pres- 
sure is low, and no pump is used to supply loss by leakage; the 
power produced is very small for the size of the engine. The 
largest size made is a 2-man power, running at 270 revolutions 
per minute ; the cylinder diameter is 8 inches, length of stroke 



ERICSSON AIR ENGINB. 345 

5 inches. A drawing of this engine is given in Professor Jenkin's 
valuable paper on " Gas and Caloric Engines " (Proceedings o/ths 
Institution of CivU Engineers, 1883), from which many details 
of this and other hot air engines have been taken. 

One chief reason for the low pressures and small amount of 
work obtained from the Stirling, and its failure as a practical 
engine, was that the air was not brought into direct contact with 
the heat of the furnace. In the displacer cylinder, a thin metal 
plate intervened between the fire and the hot air, the bottom of 
which was soon burnt by the great heat. There is no exhaust 
in engines of this type, the air being used over and over again, 
and the pump only replacing loss by leakage, but this advan- 
tage is counterbalanced by the difficulty of heating the air. In 
the Cayley-Buckett engine it is passed through the furnace and, 
mingled with the products of combustion, drives up the motor 
piston, and is exhausted after expansion, as in an ordinary heat 
engine. 

Ericsson. — The latter type of motor is best exemplified in the 
celebrated engine produced by Ericsson in 1826. As an engineer, 
Ericsson was a genius not inferior to Robert Stirling. Curing 
the first half of this century he introduced numerous mechanical 
inventions, and is said to have designed the first screw propeller. 
In his engine hot air was used in conjunction with steam. It 
was drawn into a furnace below a steam boiler, and after produc- 
ing combustion of the fuel, and evaporating the water, it was 
carried ofi^, together with the products of combustion, and drove 
up the piston of an air cylinder by its expansion. On its way it 
passed through a regenerator. In an alternative engine described 
in the same patent, it was proposed to mix the products of com- 
bustion and the hot air with the steam, and admit them alter- 
nately at either end of the motor cylinder, as in an ordinary 
double-acting engine. After expansion, they were exhausted 
into the atmosphere. Thus the heat was applied directly to the 
air. Of course it was impossible to use the air over again, since 
it was required fresh at every stroke, to support combustion. 

These two engines, the Stirling and the Ericsson, form two 
distinct classes, into one or the other of which all hot air engines 
can be divided. In the first, the air does not come in contact 
with the fiame, but is heated by conduction and by the regen- 
erator, and is not discharged at each stroke. In the second, it is 
applied directly to feed the flame, and, mingled with the products 
of combustion, produces motive power by expansion, after which 
it is exhausted. In both engines the practical heat efficiency, 
as compared with the theoretical, is very low. Admirable 
as types, they cannot, for the amount of heat they turn into 
work, be ranked with gas,- oil, or steam engines. The chief 
reasons for this deficient utilisation of heat have been already 
explained. A large quantity of heat must be added to the air. 



346 AIB EHGIITBS. 

before its temperature is high enough to produce a proper work- 
ing pressure. This necessitates large cylinders, that a sufficient 
volume of air may be heated^ and their bulk, weight, and friction 
are serious drawbacks to the extended use of heat motors of this 
type. In a Stirling 37 H.P. engine, the maximum temperature 
was only 650** F., and the weight 1 ton per I.H.P. The con- 
sumption of coal per effective H.P. is also very great, especially 
in engines of the Ericsson type. The 600 H.P. engine originally 
made by Ericsson was said to consume 6^ lbs. coal per H.P. per 
hour, the heating surface of the regenerator was 4,900 square 
feet. Another of f H.P. was used for thirty years by the Trinity 
House authorities on board a lightship, and for driving a fog 
signal was found to give good results. In the Ericsson engine 
tested by Professor Norton, the I. H.P. was 321, and consumption 
of anthracite 1*8 lb. per I.H.P. per hour, but there were four 
motor cylinders, each nearly 14 feet in diameter. These two 
air motors form the standard types, followed more or less closely 
by all other hot air engines. 

Wenham. — The Wenham engine, introduced about 1873, is 
in some respects similar to the Buckett. The motor is of 
the Ericsson type, and the air is heated by forcing it through 
a furnace lined with fire-brick, after which it passes to the 
vertical water-jacketed motor cylinder, driving up the piston 
by expansion. The distinctive feature of the engine is that 
the upper surface of the motor piston ia used as an air pump. 
Air is admitted into the top of the cylinder through an 
automatic lift valve, when the piston is in its lowest position, 
and the pressure has consequently fallen. As the piston rises, 
forced up by the expansion of the heated air from below, the 
pressure closes the valve, and as soon as the air is com- 
pressed to 15 lbs., it forces open another lift valve, and passes 
to the furnace at the side. In the passage through which it 
is led off is a valve, connected to the centrifugal governor. 
Here the current of compressed air is separated, part passing 
over and part beneath the fire grate, to stimulate combustion. 
The governor regulates the proportions of the two, and thus the 
rate of combustion, and the pressure of the air delivered to the 
motor cylinder. Ordinary coal is burnt as fuel. The hot air, 
after passing upwards, is led off, mingled with the products of 
combustion, and admitted to the bottom of the motor cylinder 
through a lift valve, worked by a cam on the main shaft. 
A similar cam operates a second lift valve for the exhaust. The 
admission and discharge ports are both at the bottom of the 
cylinder. The engine is single-acting, the expansion of the hot 
air drives up the piston, it descends by the motion of the fly- 
wheel, and by the pressure of the air stored above it, and drives 
out the burnt products. There are two piston-rods, both workr 
ing on to the same crank shaft. The consumption is said to be 



BAILBT AI& B2V61NE. 



347 



as much as 8 lbs. of coal per H.P. per hour, which is probably 
the reason why these engines have not hitherto been much 
used. A description with drawings will be found in Proc. Inst. 
Mech, Engs.y 1873. 

Bailey. — The Bailey engine, shown at Fig. 130, is constructed 
on the Stirling principle. The products of combustion pass from 
the furnace to the displacer and power cylinder, where they 
mingle with and heat the air, driving the piston. The cylinder 
is horizontal, but in most respects, and especially in the arrange- 
ment of the regenerator, the Bailey resembles the vertical Robin- 
son engine. There is one long cylinder, Aj, the crank end of 
which, closed by the piston, is surrounded by a water jacket, 
and acts as a refrigerator. The other end serves as the heater 
and regenerator. This cylinder contains two pistons — P the 
motor, working on to the crank by a connecting-rod, c, and series 
of levers, and P^ the long displacer, the connecting-rod of which 




Fig. 130.— Bailey Hot Air Engine. 

passes through the motor piston, and works on to a separate 
crank at right angles to the main crank. The displacer P^ does 
not fit closely into the cylinder A^ but a small passage is left 
between them, shown at D. This piston is used merely to cause 
the air to travel backwards and forwards in the cylinder; all 
the work, including that of driving the displacer, is done by the 
motor piston. At H is a steel casing enclosing the inner end of 
the cylinder ; F is the furnace. The hot gases and products of 
combustion pass upwards from the furnace over the fire bridge, 
in the direction of the arrows, into the space G round H, and 
the burnt products are carried ofif through the flue C. The air 
enclosed in the space L becomes highly heated, and drives out 
the displacer. As it reaches the narrow opening D, it is chilled 
by the water jacket, and before it has passed into L^ on the 
other side of the displacer piston P^, it has parted with all its 



348 AIR EKGINE& 

heat. As the air cools its pressure is reduced, the working 
piston and displacer make their return stroke, and the cold air 
is drawn back into the space L, to be reheated first by the steel 
casing, then by the furnace gases. Thus the heat is added when 
the temperature of the air has already been raised by the hot 
end of the cylinder, and withdrawn by the refrigerator after it 
has been cooled by expansion. 

The Bailey engine is said to be based on the designs of MM. 
Lehmann & Laubereau, but it is really an English engine, strictly 
modelled on the Stirling type, though the idea of a regenerator 
is not much developed. There is no exhaust for the hot air, 
which is used continuously, and the loss by leakage is replaced 
from time to time through a small valve, when the pressure falls 
below atmosphere. The absence of valves is an advantage in 
this class of engine, because the great heat necessary to obtain a 
working pressure soon wears them out, and causes them to become 
loose. As the air is introduced direct from the surrounding 
atmosphere, and no compression pump is used, the maximum 
pressures are very low. The following details of a trial from 
Professor Jenkin's paper on "Gas and Caloric Engines" gives 
the working of a Bailey hot air engine: — The speed was 106 
revolutions per minute, and the engine indicated 2-37 H.P. ; the 
mechanical efficiency was 55 per cent., the brake H.P. being 1*31. 
The stroke was 6| inches, diameter of cylinder 14^ inches. The 
highest pressure obtained was 14*7 lbs. per square inch above 
atmosphere, and the temperature at this pressure was 823" C. 

The consumption of 
coal w^as said to be 

hour. Fig. 131 
gives an indicator 
diagram taken dur- 
ing this trial. The 
Fig. 131.~Bailey Hot Air Engine— engine works easily 

Indicator Diagram. and steadily, and 

requires scarcely 
any attendance. Messrs. Bailey make 7 sizes, from | to 3J- H.P., 
at speeds from 1 20 to 80 revolutions per minute. 

The figures of the trial show that to obtain a pressure of only 
one atmosphere, a relatively high consumption of coal and high 
temperature are necessary. These are partly owing to the trans- 
mission of the heat through metal to the air. But the difficulty 
is not removed by passing the air directly over the fire, as in the 
Ericsson engine, and driving the piston by the expansion of the 
hot furnace gases. Since the air must be discharged at every 
stroke, fresh air is continually introduced, and much of the heat 
obtained is wasted at exhaust. It has also been found that the 
air, in its passage through the furnace, becomes charged with grit 




RIDER AIR ENGINE. 349 

and unbumt carbon, which score the valves and passages, and 
cause friction and wear of the working parts. 

Bider. — The Rider is an ingenious little hot air engine brought 
out in America, and made in this country by Messrs. Hay ward 
ii Tyler. It is a compact and handy single-acting motor, and is 
used for domestic purposes, and to pump water. It presents 
almost all the features of the Stirling type, the regenerator, the 
furnace below heating the air through metallic walls, with no 
exhaust or other valves. There are two vertical cylinders, as 
shown at Fig. 132 ; one is heated by the furnace beneath, the 
other is kept cool by a water jacket. The same air is used 
continuously, and is passed alternately from one cylinder to 
the other. Unlike the Stirling, however, the motor piston is 
placed in the hot cylinder of this engine, and it is here that the 
power is developed. A is the working, and B the second cylinder, 
which acts as compressor, displacer, and refrigerator. Each has a 
plunger piston of unequal stroke and diameter, P and Pj, working 
through connecting-rods, J and J^, on two cranks on the main 
shaft, carrying the flywheel. The cranks are set nearly at right 
angles. The cylinders are open at the top, closed only by the 
pistons. W is the water jacket surrounding the compression 
cylinder B ; the piston of cylinder A ends in a concave cylindrical 
part, F, over the furnace, round which the hot air circulates. 
Between the cylinders is a passage containing the regenerator R, 
formed of a number of very thin iron plates. As the air passes 
through this regenerator it either takes in or ijives out heat, accord- 
ing to the direction in which it is going, whether from the hot to the 
cold cylinder, or back again. The fire at G greatly heats the air in 
the space above it at F, and forces up the piston P by expansion. 
Meanwhile the displacer Pj is at the lx)ttom of its stroke, it then 
Ijegins to rise slowly, drawing over into cylinder B, by its suction, 
part of the hot air in A. Until this air is completely cooled, 
its pressure helps the ascent of piston Pj. When the motor 
piston P has reached the top of its stroke, the other plunger is 
more than half way through, and as P descends, it displaces all 
the hot air in cylinder A, and drives it into the cold cylinder B, 
through the passage and regenerator E, where a large portion of 
its heat is deposited. The air, already reduced in temperature, is 
further cooled by the water jacket W, its pressure falls, and the 
plunger piston P, descends, compressing the cold air below it. It 
is during this period — the last part of the down stroke of P^ — 
that the flywheel does work, there being no air in the hot 
cylinder to act by expansion, but the power exerted during this 
compression stroke is not nearly as great, as the power previously 
developed by the expansion stroke in A. By the time the 
plunger P^ has reached the end of its stroke, the motor ])iston 
has begun to rise, and the air is again displaced and transferred 
from the cold to the hot cylinder. As it passes back, it absorbs 



350 



AIB BNGIlfEB. 



heat from the regenerator, and more heat from the concave part 
F in the motor [piston, which forces it against the hot walls of A. 
When it reaches the furnace the cycle recommences. 

The chief peculiarity of the Rider engine is that the motive 
power is not only generated but exerted in the hot cylinder. 




Fig. 132.— Rider Hot Air Engine. 

above the furnace. This is not a desirable arrangement. In all 
his various designs, Stirling was careful to keep the motor cylinder 
cool, and even in the modifications of his engine where all the 
operations take place in one cylinder, that part of it containing 



jenkin's rkgekbrative engine. 351 

the working piston is cooled by a water jacket. The Rider engine 
is mostly made in sizes from 1 H.F. and less. The speed is from 100 
to 140 revolutions per minute, and the maximum pressure about 
20 lbs. above atmosphere. The consumption of coke varies in J 
and ^ H.P. engines from 25 lbs. to 18 lbs. per B.H.P. per hour. 

Jenkin's Regenerative Engine. — A hot air engine on the 
Stirling principle, with a regenerator, but in which hot air passes 
directly over the furnace and, mingled with the products of 
combustion, drives up the piston, was introduced by Fleeming 
Jenkin. In the first type of his Fuel Eegenerative engine, 
patented in 1874, coal gas and hot air were used together to 
form an explosive charge. This vertical engine had a combustion 
cylinder with displacer piston, a motor cylinder with working 
piston, and two pumps for compressing the air and gas, all driven 
from the same crank shaft. The combustion cylinder is lined 
with fire-brick, and has below it a chamber formed by the clear- 
ance space, and continually maintained at a white heat by the 
explosions of compressed gas and hot air taking plnce in it. The 
displacer piston contains the regenerator of fine wire gauze, as in 
the Stirling engine; at the top of this cylinder is the cooling 
chamber. The air from the air pump is driven into the upper 
part, and forced downwards through the regenerator by the dis- 
placer piston as it rises. In the combustion chamber it mingles 
with the coal gas or petroleum admitted into the cylinder by a 
second pump, and the compressed air, already heated by its 
passage through the regenerator, produces the ignition of the 
charge. The hot gases and products of combustion expand, and, 
entering the bottom of the motor cylinder at a high pressure, 
force up the piston. The exhaust gases are passed through the 
regenerator before being allowed to escape into the atmosphere. 
A drawing of this engine will be found in Kobinson. 

A second regenerator engine, designed by Professor Jenkin 
and Mr. Jameson was described, with drawings, in Professor 
Jenkin's paper already referred to. Here the object was to 
construct an engine of the Stirling type, but in which the heat 
was directly transmitted to the motor piston. One cylinder only 
was used, the upper part containing the refrigerator, and the 
lower the regenerator. To keep in the heat, it was found neces- 
sary to line, not only the clearance space, but the cylinder itself 
outside the regenerator with non-conducting refractory material. 
Great difficulty was experienced in dealing with this substance, 
owing to its porosity. The inventors were finally obliged to use 
a fire-brick lining of great thickness, and a separator or metal 
plate, dividing it into two parts. Even with these precautions 
the clearance space was much too large, and there was conse- 
quently great loss of pressure. To work the engine a coke fire 
was made below the cylinder, and the air as it became heated 
drove up the pump or displacer. As it expanded, it passed 



352 



AIR ENGINES. 



through the regenerator round the circumference of the cylinder. 
Here heat was withdrawn from it, and it became still further 
cooled by contact with the refrigerator or water jacket, at the 
top of the cylinder. The contraction of the cold air caused it 
to pass downwards again to the fire, and heat was restored from 
the regenerator, and from the fire-brick lining of the clearance 
space. This enajine did not go beyond the experimental stage. 

Benier. — MM. Bonier, whose gas engine is mentioned at p. 
70, brought out in 1886 a hot air motor, which appears to have 
met with considerable success. It is a vertical single-acting 
engine ; the piston-rod works through a horizontal beam on to 
the connecting-rod and crank. Fig. 133 gives an external view. 




Fig. 133.— Bdnier Hot Air Engine. 

There is one motor piston, with furnace below ; the connecting 
rod and crank shaft are shown to the left in the drawing. 
Another rod works the horizontal air pump, seen through the 
opening in the base of the engine, by means of a rocking lever. 
The air pump is single-acting, and sends a current of air at each 
stroke to the furnace below the cylinder through a slide valve. 
The valve works between a slide face and cover, and has open- 
ings corresponding to ports in the cylinder. It is driven by a 
cam on the crank shaft actuating a lever, and is held in position 
by springs. The centrifugal governor inside the central column 
is worked by a pulley on the crank shaft. It acts through 
a small lever, a series of rods, and a disc, upon a small 
crank below the air pump, and closes the air opening from 



AIR ENGINES. 353 

the pump to the furnace more or less according to the 
speed. A spring maintains the disc and crank in position. 
The air is drawn cold into the air pump, and delivered 
at a pressure of 15 lbs. per square inch into the furnace, where 
it expands and acts directly upon the piston, as in engines 
of the Ericsson type. The greater part passes downwards to the 
grate, but part is ingeniously introduced into a small groove 
hollowed out in the cylinder. The motor piston is very long, 
and the lower part is made slightly smaller than the cylinder, 
and does not exactly fit it. In the space thus formed round the 
lower end of the working piston, the current of cold air circulates, 
keeps the piston cool, and prevents the escape of dust or unburnt 
carbon from the furnace below. The exhaust is on the other 
side of the cylinder. The products of combustion are discharged 
through an ordinary lift vsdve, raised as the motor piston begins 
to descend, by levers acted on by a cam on the crank shaft. The 
furnace is fed automatically by means of two hoppers. The 
proper quantity of small coke for each charge is conveyed from 
one to the other, and the second hopper, shown to the right in 
the drawing, discharges its contents into a port in a slide valve 
which, in its onward motion, shoots the coke down into the 
furnace. This distributing slide valve is driven by wheels from 
the crank shaft, and holds the grate hermetically sealed during 
expansion and the ascent of the piston. 

The B6nier appears to be one of the simplest and most efficient 
of the hot air motors, and requires no attention beyond cleaning 
out the grate once a day. For coast fog signals it has been tested 
and approved by the Trinity House Authorities, and is much 
used in France. Although it works without a regenerator, it 
gives fairly economical results. A 7 H.P. engine was shown 
at the Paris Exhibition of 1889, in which the consumption of 
coke was about 2 lbs. per H.P. per hour. In a 6 H.P. engine 
the average consumption, with varying loads, was 3 lbs. coke 
per H.P. per hour. A complete and careful test on a 4 H.P. 
nominal engine was made by Professor Slaby at Cologne in 
December, 1887. The speed of the engine was 117 revolutions 
per minute. The total indicated work in the motor cylinder 
was 9-23 H.P., pump 338 H.P.; available power only 585 H.P. 
The B.H.P. was 4*03, and mechanical efficiency 69 per cent. 
The consumption of coke was 3*6 lbs. per B.H.P. and 3*1 lbs. 
per I.H.P. per hour. All the items of heat expenditure were 
carefully noted, and it was found that only 6 per cent, of the 
total heat supplied was transformed into useful work. The 
makers give the consumption of coke at from 3*3 lbs. to 3*9 lbs. 
per H.P. per hour. The engine is made by the "Soci^t6 
Fran9aise des Moteurs it Air Chaud," in sizes of 4, 6, 9, 12, 
and 15 H.P. Some of these hot air engines are working in 
England. 

23 



354 AIR ENGINES. 

Diesel. — A new motor has lately been patented in Germany, 
England, and other countries, by Herr Diesel, of Berlin, It is 
still in the experimental stage, but the inventor hopes to obtain 
a very much greater economy of heat than has hitherto been 
reached. It is a single cylinder, vertical, single-acting engine, 
without a water jacket, employing the Beau de Kochas four-cycle, 
and designed to run at a speed of 300 revolutions per minute. 
The principle of the engine is as follows — Air is compressed in 
the motor cylinder by the up stroke of the piston to a pressure 
of from 90 to 200 atmospheres, equal to about 800' to 1000' C. 
Into this highly compressed and heated air a small quantity of 
finely-powdered coal, gas, or oil is introduced at the dead point ; 
spontaneous ignition of the inflammable mixture immediately 
takes place, and the piston is driven down. The inventor claims 
to utilise about 35 per cent, of the actual heat supplied in useful 
work, and experiments are now being made with a medium sized 
motor in Germany. A full description of the new theory of 
eombustion on which this engine is based, will be found in Herr 
Diesel's new work, Theorie and Konstruktion eines Bationdlen 
Wdrmemotors, [Julius Springer. Berlin, 1893. 



APPENDIX. 



SECTION A. 

PROFESSOR CAPPER'S GAS ENGINE TEST. 

December, 1802. 

Thb author has been kindly permitted to publish the following experiment 
made on a 7 H. P. nom. Crossley-Otto engine, at which he was present. 

The trial was carried out at the King's College Engineering Laboratory 
by Professor Capper. Annexed is his report : — 

A series of trials has lately been carried out in my laboratory with 
a 7 N.H.P. Otto gas engine, constructed on the Beau de Rochas cycle by 
Messrs. Crossley Srothers, and in one which I made on the 7th December, 
1892, interesting particulars were obtained as to the composition of exhaust 
.gases, and the transmission of heat through the cylinder walls. 

The engine was built in December, 1891, and completely fitted up for 
experimental purposes. Ignition is accomplished by a red-hot tube and 
timing valve, as described in the report on the Society of Arts trials, and 
the pendulum governor acts upon the admission valve, cutting off the gas 
supply^ when the speed becomes too great. At full power there is an 
•explosion every two revolutions. The diameter of the cylinder is 8 '5 inches, 
«na the stroke 18 inches. The trial on 7th December lasted for two hours, 
the brake horse-power being 11*33, and the revolutions 162*5 ][>er minute. 
With 71*2 explosions per minute, about three-quarters of the maximum 
power was thus developed. The principal observations were taken every 
■five minutes, and it was intended to Uike indicator diagrams at similar 
intervals, but this was found impossible, owing to the necessity of changing 
indicator springs when diagrams for the pumping stroke were obtained. 
There were thus nine diagrams taken each hour with a Crosby indicator 
-and Y^ spring (160 lbs. = 1 inch). For the pumping stroke a second 
^ * *aai< 



Crosby indicator was used, with ^ spring, and both gave reliable diagrams. 
7 of the pumping stroke diagram is given at Fig. 134. 
be accompanying tables, the averages for each hour and for the whole 




Fig. 134. 

period of two hours are given, and also copies of the indicator diagram 
nearest to the mean. For the purpose of calculation, a mean diagram, the 
•ordinates of which are the mean of the corresponding ordinates of all the 



356 



APPENDIX. 



diagrams taken during the trial, has been constructed (shown by a full 
line, Fig. 135), and the expansion and compression lines (dotted) have 
been assumed. 

The expansion curve (dotted) corresponds to the equation p x v^** = 
constant, and the compression curve (dotted), p x v^*^^ = constant. It 
will be seen that they both very closely approximate to the actual curves of 
the mean diagrams. 

The net work done with the ideal diagram A,B}C,D,£ (see Fig. 136) =■ 



8Bta*F C^D 30*S*F 



•453 -S73 

Volitmea in cuhir/ftt. 



iHofffXtni 

Taken at fo^t. 

Mean Pressure -7«<»» 

Explosion$^70J 




Fig. 135. 



6,594 ft. -lbs. per stroke, as compared with 6,345 ft. -lbs. from the actual 
indicator diagram. 

Indicated Horse-Power.— The mean pressure was 74*56 lbs. during the 
working stroke, and the corresponding indicated horse-power is 13*69. 
Allowing for the work expended during the pumping stroke, which cor- 
responds to a mean pressure on the piston of 2 lbs. per sq. in., the net 
indicated horse-power was 13*32. 



CAS ENGINE TRIAL. 357 

Brake Horse-Powar. —For absorbing the power, the flywheel was fitbed 
with the usual rope brake, having a weight at one end and a spring balance 
at the other. A double rope was wound once completely round the circum- 
ference of the wheel, ana the two portions were kept apart by wooden 
distance pieces attached to the rope. A little paraffin oil was used occasion- 
ally as a lubricant for keeping; the wheel cool, and the whole worked very 
steadily, there being very little fluctuation on the reading of the spring 
balance. The brake horse-power was, as already stated, 11*33, and cor- 

1 1 '33 
responds to a mechanical efficiency of i^Too = 85 '06 per cent. In other 

words, the B.H. P. was equal to 85 per cent, of the I.H.P. 

Gas Consumed. —The gas was measured through a 100-light standard 
meter, made by Messrs. Alex. Wright & Go. The same meter was employed 
at the Newcastle and Society of Arts trials. 

LH.P. to drive Bngine alone. — This is the difference between the B.H.P. 
and the I.H.P., and at 162*5 revolutions = 1*99 H.P. 

Jacket Water for Cooling the Cylinder. —This was measured by running 
water through the jacket to waste from two tanks, previously very 
carefully calibrated. Readings were taken every five minutes on gauge 
glasses fitted with graduated scales. 

Calculations for Air used. — The quantity was not actually measured, but 
has been determined by the folio win$^ indirect method :— 

The meter temperature being 57''*6 F. and the pressure (1*68 inches of 
water above atmosphere) » 14*86 lbs. per sq. inch, the specific volume of 
the gas under these conditions would be — 

144*1 X (57"*6F. + 460' abs.) ,. ^. , ,^ „ 

rr86^ri44 = ^^^ °^^- ^*- p^' ^^- 

(144*1 = the constant = the difference in ft. -lbs. between the specific 
heat at constant pressure (K^) and the specific heat at constant volume 
(Kj for London coal gas.) 

279*75 cub. fb. were passed through the meter per hour, equal to 

279*75 cub. ft. ^naK4A i> *4. 1 • 

st: — : ^rm = 0*06544 cub. ft. per explosion, 

60 mm. X 71*2 exp. ^ ^ 

*06544 

Q..^- = '001877 lb. per explosion. 

Assuming that its temperature after admission to the cylinder is = 145"* P., 
or rather higher than the exit temperature of the jacket water (see Table 
III.), and that its pressure, as shown by the pamping diagrams, was 
13*8 lbs. per sq. inch, the gas would then have a specific volume 

144*1 X (14.r + 460'') .- ^, , ,^ ,, 

13-8 1bs. X144 -^^•^^^^^^•^^•P^'*^^- 

and would occupy a total volume = '001877 lb. x 43*81 

= '0822 cub. ft. 

The volume of the cylinder + clearance is as follows : — 

'591 cub. ft. + *2467 cub. ft = *8377 cub. ft. ; 

the volume occupied by the air 

= -8377 cub. ft. - -0822 cub. ft. = "7556 cub. ft., 



[53*35 ifl i 
K, 130 20, 



358 APPENDIX. 

and its specific yolame under the same conditions of temperature and 
pressure — 

63-35 X 605* abs. ,-^- , .^ « 
= 13-8 lbs, X 144 = ^^"^ ^'^^^ '*• P«' ^^- 

difference in ft. -lbs. between specific heat at constant Yolome, 
and specific heat at constant pressure, K, 183*55 for air.] 

. •, the weight of air present = ^^ = -0405 lb. 

I 0-04050 air. 
0-00188 gas. 
0-04838 lb. 

-,1. .. air . , -7556 9188 
The ratio— = by volume ^^jg^g = "T"- 

, . , ^ -0465 24775 

„ „ = by weight ,^^j3g = —j—. 

After combustion, the specific heat at constant volume (K^), and specific 
heat at constant pressure (R^) will be by Grashof s formulae — 

«, -2375 X 9188 + '343 -.„ ^. -. ^ ,, 
^' = 9188 + -48 "" ^^2 = ^^'^^ ^••^^• 

« -1684 X 9188 + -286 --„ , .^ «- .^ „ 
K. = Q:iss-inA ^ ^^2 = ^^'^ ^*-^^ 

Their difference— 

(K^ - K^) = ic = 55-40 ft. -lbs. 

and the ratio — 

Kp 201-75 _ 

Temperatures in Cylinder. — The temperatures calculated on this basis 
for the several portions of the stroke will then be as follows : — ^Assuming, 
as above, a temperature of 145° F. for the gas snd air after admission to the 
<r^linder at A on the mean diagram, and taking the pressure given on that 
diagram, we shall have a temperature at B after compression : — 

" ^ " 53-35' 
if we assume, as is probable, that the mixture behaves in compression 



approximately as air, 
The pressure 



pressure {p) = 67-8 lbs. x 144 = lbs. per sq. ft., the specific volume 

(„) = ^7_ (5»^»«^) = 6-099 cnb. ft. per lb. 

-04838 (weight of gas and air) ^ 

.^ ^ 67 8 lb,. X 1^ ><6-099 cub, ft _ ^^33. ^^ ^ ^^3, ^ 



GAS BNOINB TRIAL. 359 

At C, after heat has been added at oonstaot Tolome, the temperature will 
be, with a pressure of 240 lbs. per sq. inch— 

' ^ySr*" = 3,30{r abs. » 2,842- P. . 

At D, where the volume = '2617 cub. ft., after further reception of heat 
at constant pressure, the temperature will be 

_ 3302 X. 2617^3 ,^3. ^^_ 3^^^ p 



•2467 

At E, where the pressure on the ideal expansion curve =48*71 lbs. per 
•q. inch, and the volume occupied a '8377 cub. ft., the specific volume of 
the -04838 lb. of gas and air 

•8377 cub. ft. ,-«, , .^ ,, 
= -04838 cub. f t = "-'^ *"^- **• I*' ^^• 

... the ten.pen.tar, = ""^VMorlli^iu'rer = '^•"'° "" = '''^'' ^' 

Heat r^ected. — The quantities of heat turned into work, and rejected in 
the jackets and exhaust will, therefore, be as follows : — 

13'69 I.H.P. = ^^'^^y^.^'^^ = 6,346 ft.-lbe. per explosion 

turned into work. 

Multiplying the water passed through the jackets for each five minutea' 
interval by the corresponding rise in temperature, the mean value of the 
heat rejected through the jackets per explosion = 10,825 ft. -lbs. 

The heat rejectea in the exhaust will evidently be equal to the difference 
between the internal energy of the gases under cooditions £ and A, 
although it must be noted that some portion of the heat thus calculated 
will pass into the jacket water during release, and will thus be reckoned 
twice over. The heat account on this basis should, therefore, over- 
balance. 

The heat rejected in exhaust will be — 

E, (2,19r - 605') X -04838 lb. = 146-35 (1,586) x -04838 = 11,245 fL-lbs. 
. per explosion. 

As a check upon this quantity, the reception of heat from B to C at 
constant volume 

== K, (3,302° - 933**) x -04838 lb. » 146*35 (2,369) x -04838 n 16,775 ft-lbs. 

And at constant pressure C to D 

- Kp (3,503°-3,302')x -04838 lb. =201 '75 (202) x -04838 = 1,971 ft-lba. 

During compression, the heat added will be equal to the difference 
between the internal energies at the beginning and end of the process 

= K, (for air) (933* - 605") x -04838 lb. = 130'2 x 328 x -04838 = 2,066 
ft..lb8. 



360 APPENDIX. 

The work done during compression where p v ^''^ is constant 
^Pi^i_-_^.a3=, l^ = (67-8 lbs. X -2467 clearance - 13-8 lbs. x -8377 total 

71-1 '*>Ui& 

vol.) (where n = 1-302) = 2,465 ft-lba. 

Adding together the heat received, 

16,775 + 1,971 + 2,066 = 20,812 ft. -lbs., 

and subtracting the total work above zero pressure, 

6,346 ft. -lbs. + 2,465 ft. -lbs. = 8,810 ft. -lbs., 

we have 20,812 - 8,810 := 12,002 ft. -lbs. as the remainder rejected, calcu- 
lated from D, where expansion commences. During expansion the loss of 
internal energy 

= K. (3,603" - 2,19r) -04838 lbs. = 146-35 (1,312) 04838 = 9,288 ft-lbs. 

The work done 

= &_"!.- f)L-, ^here n = 1-374 = 240 x (-2617 - 48-71) x -8377 ^ ^^ 
n - 1 -374 

= 8,470 ft. -lbs. 

The difference between these Quantities will evidently haVe been passed 
into the jacket or lost by radiation, and will, therefore, have to be 
subtracted from the above 12,002 ft. -lbs., in order to give the intemiJ 
energy remaining to be disposed of at E. 

12,002 - (9,288 - 8,470) = 11,184 ft.-lbs., as compared with 11,245 ft-lbs. 
by direct calculation. 

Heat Account. — On the Dr. side of the account we have the heat 
developed by the perfect combustion of '001877 lbs. of gas per explosion. 

In order to determine the calorific value of the gas, samples were taken, 
under mercury, at intervals throughout the trial, and analysed by Mr. G. 
H. Huntly, A.R.C.S., of the State Medicine Laboratory, King's College, 
London. The analysis is given in detail in Table V. The calorific value 
la shown in the last column of this table. Taking this in round numbers 
as 19,200 B.T.U. per lb., we have for the perfect combustion of -001877 lb. 
of gas per explosion, '001877 x 19,200 x 772*= 27,820 ft. -lbs. developed 
per explosion, and the heat account works out as given in Table V. It 
will be seen that the Cr. side overbalances the Dr. side by about 2^ per 
cent., from the unavoidable double reckoning of a portion of the heat 
credited to exhaust. 

Analysis of Exhaust Qases.— In Table VI. will be foimd the analysis of 
the exhaust gases. These were also carefully sampled under mercury. It 
will be seen that they are quite free from CO, and that the combustion is, 
therefore, probably complete. 

As a check upon the necessarily approximate nature of the sampling, 
Mr. Huntlv has calculated what the exnaust products should be, if com- 
bustion takes place with 9-188 volumes of air and 1 volume of the gas 
analysed above. The result is given in the second colunm of the same 

* 772 = ft. -lbs. per B.T.U. or Joule's Equivalent. 



GAS ENGINE TRIAL. 3G1 

table, and agrees very well as to CO and COs with the actual prodncts 
found. There is, however, considerable excess of oxygen in the calculated, 
over the found values of the products. This is probably to be accounted 
for by the difficulty of obtaining a really average sample. The results are, 
however, worth recording as a close approximation to accuracy. 

The oxyeen necessary to convert the known value of the hydrogen to 
water has been allowed for in the calculation, the analysis having been 
carried out dry. 

Transmission of Heat through Cast -Iron Jacket Wall.— The total 
heating surface (the internal surface of cylinder plus the clearance) 

= 740 sq. inches = 5*14 sq. ft. 

Therefore heat transmitted to jackets per sq. ft. per hour 

10,825 X 71-24 x 60 x 144 ,, -^^ « ,^ , 

= 772x^740 = 11,660 B.T.U. per hour. 

But transmission probably only takes place during the out stroke, therefore 
the rate of transmission for the revolutions per hour = 9,750, and the 
explosions = 4273*5 per hour 

1 1,660 B.T.U.X 9,750x2 „inm>rrTT i. 0000^x1 

= -r^r=^ ;v— ^ = 53, 1 90 B. T. U. pcr hour = 886 B. T. U. per mm. 

The cooling surface (external surface in jacket space of cylinder metal) 
= 926*6 sq. inches = 6*43 sq. ft. 
Therefore the rate of transmission per sq. ft. of cooling surface 

= ^'^'^^^3^^^ =42,525 B.T.IJ. per hour=709 B.T.U. per sq. ft. per min. 

Taking the mean temperature of the jacket water as equal to 90" F., and 
the temperature of the gases when most of the heat would pass into the 
jackets, as equal to 2,9(X)° F. the rate of transmission, by formula given by 
Kankine, should be approximately : — 

{2^90^^^y = 49,350 B.T.U. per hour per sq. ft, 

which very closely agrees with the actual rate of transmission as above. 

The thickness of the cast-iron cylinder wall is about }". The internal 
surface of the cylinder in contact with the hot gases is called the heating 
surface ; the external surface of the cylinder in contact with the jacket 
water is called the cooling surface. 

A graphic diagram is added at Fig. 136, giving on a time basis the follow- 
ing particulars of the trial : — Explosions per minute, revolutions per minute, 
mean pressure, indicated horse-power, brake horse-power, gas consumption, 
heat rejected in jacket water, total explosions, total revolutions, total water 
through jackets, total expenditure of energy in millions of foot-pounds, 
isnition gas, &c. In another trial, made by Professor Capper on the 2nd 
November, 1892, on the same engine, with the same load, results were 
obtained very closely agreeing with those of the present trial. 



362 



APPENDIX. 




0A8 ENGIKB TBIAL. 



363 



TABLE I. 

RxsuLTs OF Two HouBs* Test on Si" x 18* Otto Gas Engink- 
London Oas, 



1. Duration of test in hours, 


1st hour 


2nd hour 


mean 


2. Number of indicator diagrams taken, 


9 


9 


18 


3. Average initial pressure above atmo- 








sphere in lbs., from mean diagram, 


227-5 


225-6 


226-5 


4. Average mean pressure during work- 
ing stroke from diagram in lbs., . 








7416 


74-98 


74-56 


5. Average mean pressure during pump- 
ing stroke in lbs., . 








2 


2 


2 


6. Net average pressure (4 - 5) in lbs., 


7216 


72-98 


72-56 


7. Revolutions per minute, . 


162-6 


162-4 


162-5 


8. Explosions per minute by counter, . 


69 06 


73-42 


71-2 


9. Indicated H.P; for working stroke, 


13-20 


14-19 


13-69 


10. Indicated H.P. net (including pump- 








ing stroke), 


12-85 


13-8 


13-32 


11. Load on ropeVake in lbs., . 


20201 
71 -2 J 


202O1 
65-3/ 


202-0^ 
68-2/ 


12. Reading of spring balance, net lbs., 

Difference, .... 

13. Radius of flywheel, ins.,. 


130-8 


136-7 


133-8 


33 


33 


33 


14. Brake H.P., 


10-96 


11-71 


11-33 


16. Mechanical efficiency of engine, per 








cent, line 10 and 14, . . . 


85-3 


84-85 


85 06 


16. Gas used per hour (without ignition) 
in cub. ft., 








271-9 


287-6 


2797 


17. Gas used per hour (ignition) in 








cub. ft., 


5-94 


696 


6-95 


18. Total gas used (main and ignition) 
in cub. ft, 








277-84 


293-56 


285-65 


19. Pressure of gas at meter, ios. of 








water, 


1-7 


1-66 


1-68 


20. Temperature of gas at meter in 








degrees F., 


58 


68 


58 


21. Gas per I H.P. per hour in cub. 








ft., 


20-6 


20-3 


20-45 


22. Gas per I.H.P. per hour (including 








ignition) in cub. ft., . 


21-05 


20-69 


20 87 


23. Gas per brake H.P. per hour in 








cub. ft., 


24-8 


24-6 


247 


24. Gas per B.U.P. per hour (including 








ignition) in cub. ft, 


25-35 


25-17 


25-22 



364 



APPEKDIZ. 



TABLE n. 
Results of Test— Continued. 



1. Town gas used per explosion (volume through 

meter), . . . . 

2. Pounds gas used per explosion, 

3. Calorific value of London eas per explosion, 

calculated from analysis, thermal units, 

4. Mechanical equivalent of ditto, ' . 

5. Work done on charge during compression, . 

6. Work done by charge calculated gross, . 

7. Net work done by charge in ideal process, 

A,B,C,D,H:. Fig. 136, 

8. Actual net work done, mean of all indicator 

diagrams, 

9. Efficiency of engine (actual) 

Heat turned into work _ 6.345 
Wholeheat expended ""27,820 
10. Efficiency of engine (maximum theoretical) 
Ti-To_ 3,503° -605° 

Ti " 3,503" . . • . 

Actual effi ciency 0*228 

Maximum theoretical efficiency "~ 0*827 * * 

, Rate of transmission of heat through cylinder 
wall, per sq. ft. (internal) surface per 
hour, 

, Do. do. per sq. ft. (external) surface of 
cylinder per hour, 

. Do. do. per sq. ft. (internal) surface of 
cylinder per minute, 

. Do. do. per sq. ft. (external) surface of 
cylinder per minute, ..... 



-06544 cub. ft. 
•001877 lbs. 

36-04 B.T.U. 
27,820 ftlbs. 
2,465 „ 
9,059 „ 

6,604 „ 

6,345 „ 

'228 per cent. 

•827 „ 
•275 „ 

53.190 B.T.U. 
42,525 „ 

886 „ 

709 „ 



TABLE in. 

Resdlts of Test — Continiied, See mean indicator diagram for 
A,B,C,D,E, Fig. 135, p. 356. 

Assumed temperature of gas and air after enter- 
ing the cylinder (A), 145' F. 

Calculated temperature after compression (B), . ' " " 

Calcalated temperature after reaching maximum 
pressure (C), 

Calculated temperature after beginning to fall in 
pressure (D), 

Calculated temperature at end of expansion (E), 

Mechanical equivalent of heat carried off by 
jacket water per explosion, 

i In -going temperature, .... 
Out-going temi)erature, 
Difference (rise), . . . 97"-6 



145' F. 
473' F. 


605' abfl. 
933' „ 


2,842' F. 


.S,302' „ 


3,043' F. 
1,731' F. 


3,503' „ 
2.191' „ 


10,825 ft. -lbs. 
42'-2 F. 
139'-8 F. 



GAS ENGINE TRIAL. 



365 



TABLE IV. 

Results or Test — Continued. See Indicator Diagrams for 
A,B,C,D,E, Fig. 135. 

Ft.-Lbi. 
Heat taken up by charge during compression, A to B, . . . 2,066 
>, ,, „ increase of pressure at constant 

volume, C to D, . . . 16,776 
», „ „ increase of volume at constant 

pressure, D to E, . 1,971 

Total 20,812 

Total amount of heat turned into work above zero pres- 

flure, 6,345 + 2,465 = 8,810 

Heat rejected to jacket duriog expansion, add . 818 

9,628 



Difference = heat rejected in exhaust, . 11,184 

Heat rejected in exhaust by direct calculation, .... 11,245 

TABLE V. 
Heat Balance Sheet. 

Ft -Lbs. 
per Explo- 
sion. 

Total heat due to perfect Heat turned into work, 

combustion of -001877 lb. I „ rejected in jacket water, 10^825 

of gas, . . . . 27,820 | „ „ exhaust, . 11,245 



FtLba. 
per Explo- 
sion. 
6,345 



27,820 ' 
Proportional Values. 



28,416 



Net work done, . 
Heat rejected in jacket water, 
„ „ exhaust, 



Percentiifce of whole 
heat of combustion. 

22-8 

38-9 

40-5 



(2 '2 per cent, over balance fur reasons giveo) 102 '2 



TABLE VI. 
Analysis of London Oas used, (Gas Light and Coke Co.) 





1 

Yolnme Weight in 
per one cab. 
cent ft. of gas. 


Propor- 
tion by 
weight. 


Calorific ratae , Calorific ralue 
perlh. 1 in lib. of gas. 


CH4, . 

Olefines, C8H4+C4H8, 
Hydrogen, . 

Nitro^n, '. '. ! 
COs and Oxygen, 


31-5 

51 

51*2 

77 
3 
1-3 


•01408 
•00599 
•00286 
•00603 
•00235 
•00159 


•4279 
•1821 
•0869 
•1833 
•0714 
•0484 


23,200 ft. -lbs. 
21,200 „ 
52,500 „ 
4,300 „ 


9,928 T.U. 
3,861 „ 
4,562 „ 
788 „ 

... 




... 1 03290 


1-0000 


... 


19,139 T.U. 



366 APPENDIX. 

TABLE VII. 
Analysis of Exhaust Gases taken as dry. 





Per cent. Tolame. 


Experiment. 




CO]. Carbon dioxide, 

Of, Oxygen, 

CO, Carbon monoxide, 

Nj, Nitrogen (by difference) 


6-76 
614 
nil. 
87-10 


6-46 
8-94 

nil. 

84-6 


By volume, . 


100 00 


100-00 



SECTION B. 

ABSTRACT TRANSLATION OP BEAU DE ROCHAS' CYCLE. 
(French Patent, 1862.) 

CoNCEKKiNO Compression in a Gas Engine. 

The conditions for perfectly utilising the elastic force of gas 

in an engine are four in number : — 

I. The largest possible cylinder volume with the minimum boundary 
surface. 

II. The greatest possible working speed. 

III. Greatest possible number of expansions. 

IV. Greatest possible pressure at the beginning of expansion. 

The characteristic of gases to disperse over a given area can be turned to 
excellent account in pipes, but is, on the contrary, evidently an obstacle to 
the utilisation of the elastic force developed in the gaseous mass. It has 
been shown [in a former part of the patent] that in pipes the utilisation — 
that is, the heat transmitted— is in proportion to the diameter of the pipe. 
In cylinders, therefore, the loss would be in inverse ratio to the diameter, 
but this only applies to cylinders of very small diameter, and the loss really 
diminishes more rapidly m proportion to the increase in diameter. Thus 
the typical design, which, for a ffiven expenditure of gas, assigns a cylinder 
of the largest diameter, will in this respect utilise the most heat. We may 
also conclude that, as far as possible, only one gas cylinder should be used 
in each separate engine. 

But the loss of heat in the gas depends also on the time. Other things 
beinff equal, the cooling will be greater the slower the speed. Now greater 
speed seems to entail a cylinder of small volume ; but this apparent contra- 
diction disappears if we remember that, for a given consumption of gas, the 
stroke is not necessarily and invariably limited to the volume of the 
cylinder. 

In utilising the elastic force of gas it is necessary, as with steam, that 
expansion should be prolonged as much as possible. In the typical design 



BEAU DE ROCHAS' CYCLE. 367 

described above, there is a mazimnm of expansion for each particular case, 
although the effect is necessarily limited. The arrangement will, therefore, 
ffive the best result, which restores to the motor what may be called its 
uberty of expansion, that is to say, the power of expanding as much as may 
be thought desirable, within practical working limits. 

Lastly, the utilisation of the elastic force of the gas depends upon a 
function closely allied to prolonged expansion and its advantages. This is 
the pressure, which should be as great as possible, to produce the maximum 
effect. Here the question clearlv is to obtain expansion of the gases when 
the^ are hot, after compressing them while cold. This is to a certain extent 
an mverse method of prolonging expansion to that employed when a vacuum 
is formed. The latter process is not at all suited to gases, because all such 
•compression necessitates an equivalent condensation, and even supposing 
the gases were combustible, it would be impossible to heat them instan- 
taneously. 

Theoretically, therefore, it is possible to utilise the elastic force of the 
.gases without limit, by compressing them indefinitely before heating, just 
as the elastic force of steam may be utilised without limit, by prolonging 
expansion indefinitely. Practically an impassable limit is attained, as soon 
as the elevation of temperature due to previous compression causes 
spontaneous combustion. If compression be tnen continued, the work done 
by it would be represented by expansion prolonged to the same point, less 
the loss caused by all useless work. The natural limit is here reached, and 
the arrangement which best attains it will utilise to the most advantage the 
heat supplied. 

The question of heat utilisation being thus stated, the only really 
practical arrangement is to use a single cylinder, first that the volume may 
oe as large as possible, and next to reduce the resistance of the gas to a 
minimum. The following operations must then take place on one side of 
the cylinder, during one period of four consecutive strokes : — 

I. Drawing in the charge during one whole piston stroke. 

II. Compression during the following stroke. 

IIL Inflammation at the dead point, and expansion during the third 
■stroke. 

IV. Discharge of the burnt gases from the cylinder during the fourth and 
last stroke. 

The same operations being afterwards repeated on the other side of the 
<!ylinder in the same number of piston strokes, the result will be a particular 
type of single-acting, or half-actmg engine, so to speak, which will evidently 
4i^brd the largest possible cylinder, and what is still more important, 
previous compression. The piston speed will also be greatest in proportion 
to the diameter, because the work is performed in one single stroke, which 
would otherwise occupy two. Clearly it is impossible to do more. 

As the temperature of the gases coming from a furnace is practically 
•constant, and that of the external atmosphere varies relatively only within 
narrow limits, the initial temperature of the mixture at the moment of 
admission into the cylinder will also be practically constant. It will, 
therefore, be possible to determine the limit of compression at which com- 
bustion is produced, and to make the design of the engine conform to it. 
Thus the maximum effect will always be obtained, for each proportional 
dilution of the combustible. At the same time there will be no necessity to 
use electricity, because the starting of the engine being determined by the 
■action of the steam {sic), the gases might be admitted only when the speed 
has become great enough to produce spontaneous inflammation. In any 
case compression, by helping to mix the charge thoroughly and by raising 
its temperature, would be favourable to instantaneous combustion. If the 
initial temperature in the generator corresponded to a pressure of 5 or 6 



368 



APPENDIX. 



atmospheres, inflammation would be spontaneously produced if the ffases 
were compressed to about a quarter of the original volume, the eflect of loss 
of heat being neglected. After complete inflammation the pressure would 
be hardly 30 atmqspheres, and as combustion would be effected without 
excess of air, the pressure would in any other case (i.e., where an excess of 
air was admitted) be necessarily less. Probably, therefore, in many cases, 
the absolute limit of utilisation of the heat may be attained. 

We may sum up the question by saying that, although the typical 
arrangement here described can be most completely and perfectly adapted 
to the utilisation of the elastic force developed by combustion at constant 
volume in the gaseous mass, it is quite simple. It is perhaps rather a con- 
venience than a necessity to use lift- valve distribution. This is generally 
the best method, and nothing proves that it may not be applied to the 
four-cycle type of engine. 



SECTION C. 



List of Spkcifications of Patents filed for Gas, Petboleum, ani> 
Hot Air Engines for the Year 1884. 



Hargreaves, 


326 


Skene, 


454 


Steel and Whitehead, 


560 


Sterne, 


1,373 


Wirth (Bernstein), . 


1,457 


Rodgerson, 


2,088 


Ainsworth, 


2,089 


Ofenderson, 


2,135 


Davy, 


3,778 


Woodhead, 


2,716 


Clayton, . 


2,854 


Fielding, . 


2,933 


Cobham and Gilliespie, 


3,496 


Holt and Crossley, 


3,537 


Griffin, 


3,758 


Holt, .... 


3,893 


Johnson, . 


3,986 


Malam and King, 


4,391 


Munden, . 


4,591 


Pollock, . 


4,639 


Wirth (Sohnlien), 


4,736 


Spencer, 
Crossley, . 


4,776 


4.777 


Weatherhogg, . 
Hill and Hill, . 


4,880 


5,007 


Johns and Johns, 


5,302 


>i »i 


6,303 


J. Magee, . 


6,365 


Dewhurst, . 


5,412 


Park,. 


6,435 


J. Magee, . 


6,484 


ff» . . . 


6,636 



Jan. 



Feb. 



2, 1884, 

2, 

3. 
12, 
15, 
25, 
25, 
25, 

2, 

6, 

6, 



*• 8> 

„ 18, 

M 18, 

» 22, 

„ 25, 

„ 26, 

March 5, 

), 8, 

» 10. 

» 11, 

„ 12, 

„ 12, 

„ 14, 

„ 17, 

„ 22, 

.. 22, 

„ 24, 

„ 24. 

„ 25, 

„ 26. 

„ 29, 



Speciality. 
Valves and general. 
Compressing and igniting. 
Starting and miscefianeoua. 
Silencing. 

Producing motive power. 
Compression and igniting. 
Cylinders. 

Cylinders and valves. 
Starting and miscellaneoiis. 
Compression and exhaust- 
ing. 

,, »f 

Noncompression and valves. 

Starting. 

Cylinder and stuffing boxes. 

Com]^ressing pump. 

Igniting. 

General. 

Exhausting. 

Igniting and valves. 

Petroleum motor. 

Exhausting. 

Compression. 

,, 
Igniting, gas or vapour. 
Kotatory gas engine. 

f, », 

Valves. 

,* 

Rotatory gas engine. 
Valves. 



LIST OF PATENTS. 



369 



Butcher, . . . 5,641 

Linford and Piercey, . 5,797 

Holt, .... 6,039 

Wiegand, . . 6,662 

Mugniers, . . 6,678 

M*Niel, . . 6,784 

King,. . 7,284 

...... 7,288 

Holt, .... 8,211 

Sombart, . . 8,232 

Green, . 8,489 

Rogers, . . 8,565 

Shaw. . . 8,579 

Crossley, . . 8,637 

Ainaworth, . 8,960 

Gathrie. . . . 9,001 

Grath (Daimler), . 9,112 
Williamson, Malam, 

and Ireland, . . 9,167 

Magee, 9,544 

Welch and Rapier, . 9,645 
Capitaine, . . .9,949 

Norrington, . . 10,062 

Guthrie, . . 10.483 

Shaw, . . . 10,885 

Butterworth, . . 11,086 

Justice, . . . 11,361 
Crossley, . . .11,578 

G. Magee and M 'Ghee, 1 1 , 596 
Douglas, . . .11,750 

CUrk (Hopkins), . 11,837 

J. Magee, . . . 12,023 

Griffiths, . . 12,201 

Davy, . . . 12,264 

Brine, . . . 12,312 

Dougill, . . . 12,318 

Pumell, . . 12,431 

Hill and Hill, . . 12,603 

Tellier, . . 12,640 
Reddie, . .12,714 

Wilson. . . 12,776 

... 12,777 

Davy, . . 12,842 

Andrews, . . . 13,221 

Redfern (M'Donough), 13,283 

Parker, . . . 13,766 

Lawson, . . 13,935 

Griffin, . . 14,311 

Browett, . . 14,341 

Prentice and Prentice, 14,512 

M*Gillivray, . . 14,765 

Holt and Crossley, . 15,311 

Holt, .... 15,312 

NewtoHj . . . 15,633 

B^ier, . . . 16,181 

Holt, .... 16,250 









Speciality. 


March 29, 1884, Igniting and valves. 


April 


1. 

7. 




Ignitinff. 
General. 


»» 


22. 




Igniting. 


91 


22, 




,, and General. 


»> 


25, 




Tramway loco. (gas). 


May 


6, 




Compression. 


If 


26; 




Compound gas engine. 


tt 


26. 




Supplving gas to engine. 
Miscellaneous. 


i» 


31, 




June 


4, 




)* 


4, 




Compression. 


t> 


5. 




Igniting (The Otto). 


tt 


14, 




Cylinder. 


it 


16, 




Igniting. 


»» 


17, 




Gas or oil motors. 


)t 


16, 




Valves and gear. 


»» 


28, 




Starting. 


July 


1, 




Exhausting. 


ti 


9, 




Compression. 


*t 


11. 




Assisting starting. 


f > 


16, 




Caloric engine. 


August 2, 




Compression. 


f» 


9, 




Noncompression. 


>i 


16, 




General. 


i» 


23, 




Igniting. 


tt 


25, 




(ias motor. 


it 


29, 




Exhausting. 


Sept. 


1, 




ing. 


i» 


r>. 




Igniting. 


tf 


9, 




tt 


tt 


10, 




Cylinders, valves and ex- 
hausting. 


tt 
tt 


12, 
12, 




Igniting. , 
Valves and gear. 


tf 


15, 




Compression. 


>> 


19, 




Noncompression gas or 



Oct. 



Nov. 



Dec. 



20, 

23, 

25, 

2.=i, 

26, 

6, 

7, 

17, 

21, 

29, 

30, 

3, 

8, 

20, 

20, 

27, 

1, 

10. 



vapour. 
General. 

»> 
Tramway gas engine. 

»» »» 

Cylinders and valves. 
General. 
Compression and igniting. 

tt tt 

Exhausting pump. 
Igniting. 
Exhausting. 
Starting and igniting. 
Igniting, valves and gear. 
Compound gas engine. 
Compression. 

It 
Hot-air engine. 

24 



370 



APPENDIX. 













SpMiftli^. 


Atkiniion, . 


16,404 


Dec. 


13,1884,CoiDpi«ssioii. 


MtlUer ( Adkins and 












Angus), . 


16.634 


** 


18, 


II 


Igniting. 

£lectro gas engine. 


Regan, 


16.890 


i» 


24, 


fl 


Imray (Barnes and 












Danks), . . . 


16,947 


»» 


27. 


II 


Starting, 


Radford (Martin), . 


16.992 


If 


29. 


|> 


Hot air engine. 




17,029 


»» 


30. 


tl 


Silencing. 


List of Speoifioations of Patents filed for Gas, Petroleum, and 


Hot Aib Engines 


1 roR 


Year 1886. 












SpecUllty. 


JohnBon (Lenoir), 


610 


Jan. 


1. 1885, Oenenl and Igniting. 


Myer, . . . 


848 


II 


21, 




Valves and gear. 


Pinkney, . 


1,218 


If 


28, 




General. 


Simon, 


1,363 


Peg. 


30, 




Compression. 


Asher and Buttress, . 


1.424 


2, 




Liquid fuel vapoor. 


Kempster, . 


1,581 


II 


5. 




Hydrocarbon. 


King.. . . . 


1,700 


fl 


7, 




Compression. 


Wright and Charlton, 
Atkinson, . 


1,703 


,1 


7, 




Petroleum. 


2,712 


l> 


28, 




Valves and gear. 


Beechey. . . . 


3,199 


March 11, 




Compression and igniting. 


Spiel.. . . . 


3,414 


II 


17, 




Petroleum. 


IX: : : : 


3,471 


II 


17, 




Compression. 


3,747 


1, 


23, 




General. 


Atkinson, . 


3,785 


II 


24. 




Compression. 


Mackenzie, 


3,971 


II 


28, 




Igniting. 


Daimler, . 


4,315 


April 


7. 




Petroleum. 


Garrett, . 


4.684 


II 


16. 




Valves and gear. 


Bickerton, . 


6.519 


May 


6, 




General 


Andrews, . 


6,561 


II 


6, 




Compression and governing. 


Mills,. 


5,971 


II 


15. 




II II 


Rigg, . 


6,047 


,1 


16, 




Miscellaneous. 


Weatherhogg. . 
M*Ghee and Magee, . 


6.565 


II 


30, 




Compression and igniting. 


6,763 


June 


3. 






MacGeorge, 
Campbell, . 


6.880 


,, 


6, 




General 


6,990 


II 


9. 




Compression. 


Warsop and Hill, 


7,104 


II 


11. 




Igniting. 


Capitaane and 
Brunler, . 












7,500 


II 


19. 




Compression. 


Dowson, 


7,920 


II 


30, 




Igniting. 


Newton, . 


7,929 


II 


30, 




, , and cylinders and 



Crossley, . 

Wordsworth and 
Wolstenholme, 
Humes, 

Newton (Treeton), 
Sturgeon, . 
Calton (Hortig), . 



8,134 July 4, 



8,160 
8,411 „ 

8,584 
8,897 
9.801 Aug. 



6, 
111 

15. 

23. 

8i 



stuffing boxes. 
Compression and exhaust- 
ing. 

Compression and soveminff. 

Hydrocarbon, vuves and 
gear. 

Valves, gear and governing. 

Compression. 

Non-compression and ex- 
hausting. 



LIST OF PATENTS. 



371 



Priestman and 

Priestmaiiy • 
Jofltioe (Hale), . 

Baiinler, . . . 
Grading and Harding, 
Redfem (Swyer), 
Clark (Eoonomio Motor 
Co.)* • • • 

Magee, 

Cattrall and Stoat, . 

Gillot, 

Abel (Gas Motoren-Fa- 

brik Deutz), . 
Southall, . 
Clark (Eoonomio Motor 

Co.), 
Schiltz, 

Grath (Daimler), 
Dinsmore, . 

Kaah,. 

Bnigh and Gray, 

AtkinBon, . 
Ruckteehell, 
Johnson and others, 

Bickerton, . 
Willoox, . 



Speciality. 



Aug. 
Sept. 



10,227 
10,401 

10,786 
11,215 
11,290 

11,294 

11,422 
11,555 
11,558 

11,933 
12,424 

12,483 „ 
12,896 „ 
13,163 

13,309 Nov. 



Oct 



WimiBharst, 



14,394 
15,194 

15,243 
15,475 
15,710 
15,737 
15,845 
15,874 
15,875 
15,876 
15,936 



Deo. 



28, 1885, Hydrocarbon. 
2, „ Compression, valyes and 

gear. 
11, „ Petroleam, road vehicle. 

21, „ Igniting. 

22, „ Petroleam. 



25, 
29, 



10, 
17, 

19, 
27, 
31, 

4, 

24, 
10, 

11, 
16, 
21, 
22. 
24, 
24, 
24, 
24, 
28, 



Non-compression and ignit- 
ing. 
Governing. 

t, 
Compression. 

Igniting. 
Compression. 

Igniting. 

Petroleam. 

Gas and oiL 

Compression, cylinder and 
stuffing boxes. 

Liquid fuel vapour. 

Non-compression and ignit- 
ing. 

Starting. 

Nitro cellulose. 

Governing. 

Compression and igniting. 

Starting and compression. 

Hot air „ ,, 

Cylinder and stuffing boxes. 

General design. 



Spxcifigatioms or Patents tiled tor Gas, Pbtboleum, and Hot Air 
Engines for the Year 1886. 

8peel«Ut7. 
1, 1886, Eectric ignition. 
" Compression and valves. 

Hot air and gas mixed. 

11 ,, 

Double actinff. 
Valves for exnausting. 
Road vehicle. 

Hydrocarbon. 
Iffniting and valves. 
Hydrocarbon and igniting. 
General design. 
Cooling cvlinders. 
General aesign and valves. 
Hot air and valves. 
Petroleum. 



Johnson and others, . 


11 


Jan. 


1. 


Butterworth, 


207 


,, 


6, 


Fairweather, 


477 


„ 


12, 


„ • • 


478 


f. 


12. 


Nash, . . . 


493 


f, 


12. 


Magee. . . . 


665 


„ 


15, 


Brine, 


942 


,, 


21, 


Priestman and Priest- 








man, 


1,394 


*, 


30, 


M'Ghee, . . . 


1,433 


Feb. 


1. 


Humes, 


1,464 


,» 


1, 


Welch and Rook, 


1,696 


,1 


5. 


Shillito, . 


1,797 


I, 


6. 


Haddan, 


1,958 


*, 


10, 


Eimecke, . 


2,122 


*, 


13. 


Capitaine and Bruoler, 


2,140 


„ 


13, 



372 APPENDIX. 

Skene, . . 2,174 Feb. 15, 

Leigh, . . . 2,272 „ 16, 

Shaw, . . . 2,447 „ 19, 

Boulton and Perrett^ . 2,6o3 „ 23, 

Millbnm and Haxman, 2,903 March 3, 



Deacon, 
Fielding, . 

Davjr, 

Atkinson, . 
Neil, . 

Ruckteshell, 
Dawson, 
Hutchinson, 
Justice, 

Abel, . 
Humes, 

Bernardi, . 

Benz, . 

Bedfem, 

Leigh, 

Charlton and Wright, 

Gilliespie, . 

Nash,. 

Bollason, 

Nixon, 

Bntterworth, 

Beed, . 

Roots, 

Weatherhogg, 

Fielding, . 

Johnson, 

Beeker, 

Crowe and Crowe, 

Stuart, • 

Otto, . 

Oke, . 

B(rfs and 

Cuninghame, 
Schiltz, 
Boyd, 
Humes, 
Boult, 
TumbuU, 



Hutchinson, 

Butterworth, 

Robinson, 

Rollason, 

Sutcliffe, 

Nobilings, 

aerk. 



Dec. 16, 
March 30, 
April 6, 

7, 

., 28, 
., 24. 



May 



3,010 
3,402 

3,473 
3,522 
4,234 

4,349 
4,460 

4,785 
4,881 

5,804 
6,697 

6,666 
6,789 
6,161 
6,166 
6,551 
6,612 
6,670 



7,427 June 
7.658 
7,936 

7.967 ,. 
8,210 „ 
8,436 



9,663 
9,698 
9,704 
9,727 
9,866 
9,941 
10,034 

10,332 
10,480 
11,246 
11,269 
11,576 
11,833 

12,068 
12,134 
12,346 
12,368 
12,640 
12,883 
12,912 



3, 
10, 

H, 
12, 
•'6. 



SpedaUty. 
1886, Igniting. 
„ Regulating supply of gas. 
,• Igniting and valves. 

Gas and steam, ' opposite 

sides. 
Miscellaneous and 

governing. 
Hot air, valves and gear. 
Double cylinder and 



ifi;mting. 
Bolatii 



Isolating waUs of cylinder. 
General design. 
Varying volume gas 
mixtures. 
1886, Bbcplosive compound. 
1886, Double and single acting. 
„ Petroleum. 
„ Combined gas engine and 
water pump. 
General design and valves. 
Hydrocarbon, and to pre- 
vent back ignition. 
24, „ Igniting. 

28, ,, Petroleum vehicle. 
6, „ Gas producer and motor. 
6, ,, Valves and gear. 
6, „ Petroleum and igniting. 

17, M Valves. 

18, „ Cylinders and stuffing 
boxes. 

A >» >• II 

8, ,, Double piston. 
16, ,, Combustible gas motor. 

15, ,, Hot air. 
22, „ Petroleum and ignition. 
26, ,, Petroleum, ignition, and 

valves. 

July, 23, „ Ignition. 

,, 24, ,, Carburetter for gas engine. 

„ 27, „ Hot gases and steam. 

,, 28, ,, Gas caloric. 

,, 31, „ Combining explosive fluids. 

Aug. 3, ,, Furnace by compressed air. 

t, 5, „ Hot air. 

„ 12, ,, Silencer. 

16, „ Petroleum and igniting. 
4, ,, Internal combustion. 
4, ,, Hydrocarbon and starting. 

11, „ General and carburetter. 

17, „ Manufacturer of gas for 
motors. 

22, „ Petroleum (Swan design). 

24, „ General design. 

29, „ Hot air. 
29, „ Miscellaneous and mixture. 

6, „ Utilising waste heat. 

9, „ Caloric and valves. 
11, „ Petroleum and valves. 



Sept. 



Oct. 



LIST OP PATENTS. 



373 



Macallam, • 

RuckhUl, . 
Newton (Mamy), 

Daimler, • 

M*Ghee, . 
Collier, 

Robson, 

Stuart and Binney, 

Taylor, 

Southall, . 
Wordsworth and 

Wobtenholme, 

>f it 

OrifSn, 

fiearson, . 
Priestman and 
Priestman, 



13,229 Oct. 

13,517 „ 

13,655 

13,727 „ 



14,578 
15,086 

15,307 
15,319 
15,327 

15,472 



Speoiallty. 
16, 1886, Hydrocarbon. 



22, 

25, 
26. 



14.034 Nov. 1, 



15.507 
15,507a „ 
15,764 Dec. 

15,955 „ 

16,779 „ 



11, 
19, 

24, 
24. 
24, 

26, 

27, 

27, 

2, 

6, 

21. 



Propalsion of veeaels by 

explosion. 
Guards for flywheels. 
General design, igniting and 

valves. 
Marine propulsion by gas 

or petroleum. 
Miscellaneous. 
Internal combustion,hydro- 

carbon. 
General design. 
Hydrocarbon and starting. 
General design, valves and 

gear. 
Miscellaneous. 

Hydrocarbon. 

», 
Shut off gM supply, 

automatic. 
Utilising vapour. 

Varying charges, hydro- 
carbon engine. 



ISpkcifications of Patents filbd fok Gas, Petroleum, and Hot Aib 
Engines for thb Year 1887. 



5terry, 

Boulton and Perrett, 

NewaU, 

Lake, . 

Abel, . 

Hosack, 

Charter, Gait, and 

Tracy, . 
Abel, . 
Bonier, 
Adam, 
Pfiestman and 

Priestman, 
L^nam, 
Pmkney, 
Haddan, 

Bamford, . 

Thomas, . 

Jones, 

Browett and Lindley, 

Tellier, 

Knight, 



Speciality. 
125 Jan. 4, 1887, Varying stroke of gas 

engine. 
459 „ 11, ,. Steam and hot air. 
516 „ 12, „ Petroleum. 
807 „ 18, „ Hot air. 
847 „ 19, ,, Ignition. 
888 ,, 20, ,, Heat engioe. 



1,168 


** 


25. 


»» 


Cylinders and pistons. 


1,189 


»i 


25. 


»» 


Quadruple cylinders. 


1,262 


,, 


26, 


f , 


Hot air. 


1,266 


»» 


26, 


»> 


Petroleum. 


1.454 


>, 


29, 


>> 


Hydrocarburetted. 


1.683 


Feb. 


2, 


*> 


Heat engine. 


1.986 


ft 


2, 


ft 


Gas Hammer. 


2.194 


», 


11, 


if 


Cylinders and electric igni- 
tion. 
Lubricants for gas engines. 


2,2.36 


tt 


12. 


>» 


2,368 


it 


15, 


,1 


Pistons. 


2,477 


1, 


17. 


*» 


Hot air. 


2,520 


*, 


17. 


,, 


Electric ignition. 


2,631 


f» 


19, 


*» 


Gas loco. 


2,783 




22, 


»♦ 


Hydrocarbon. 



374 

Koeber, 

Spiel, . 

Griffin, 

Redfem, 

Schmidt, . 

Griffin, • 

Beechey, . 

Ross and M*DowaU, 

Redealgh, . 

Sington, 

Howard, Howard and 

Lloyd, . 
Casper, 

Stevens, • 



APPENDIX. 



2,844 
3,109 
3,350 
3,660 
3,705 
3,934 
4,160 
4,403 

4,511 
4,564 

4,692 
4,767 

4,843 



Fob. 



Speciality. 
24, „ Caloric engine. 
„ 28, ,, Hydrocarbon. 
March 4, 1887| Putona and stuffing boxes. 



Sturgeon, . 
Wallwork, . 
Johnson, 
Bernhardt, . • 
Hurgreaves, 
Crossley, . 
Priestman and 

Priestman, . . 5,951 

Eoerting, . . . 5,981 

Dawflon, .6,501 

Faber, . . . 7,350 

Davy,. . . . 7,677 

Wastfield, . . . 7,771 
Wallwork and 

Sturgeon, . . 7,925 

Johnson, . . .8,182 

Wastfield, . . 8,466 

Beechey, . . . 8,818 

Lewis, . . . 8,883 

Haddan, . . . 9,111 
... 9,461 

Kahne, . . . 9,500 

Duevettet, . . . 9,717 

Hahn, . . . 10,176 

Bull and Bull, . . 10,202 

Dougill, . . . 10,360 

Griffin, . . . 10,460 

Tennent, . . . 11,201 

Justice, . . . 11,255 

Lindley and Browett, . 11,345 
Abel, .... 11,444 

Wordsworth, . . 11,466 

Abel 11,503 

Kiel and Bennett, . 11,567 

Embleton, . . . 11,717 

Atkinson, . . .11,911 



July 



10, 
11, 
15, 
19, 
24, 

26, 
28, 

29, 
30, 

31. 



4,923 


April 2, 


4,940 


„ 5J, 


5,095 


., 5, 


5,336 


., 12, 


5,485 


M 15. 


5,833 


M 21, 



„ 23, 

„ 25, 

May 3, 

„ 20, 

» 25, 

M 28, 

June 1, 

.. 7, 



13, 

18. 

22, 
27, 
4, 
6, 
11, 
20, 
21, 
25, 



,, 27. 

Aug. 16. 

» 17, 

» 19, 

M 22, 

„ 23, 

„ 23, 

„ 25, 

„ 29, 

Sept. 2, 



Fluid pressure motor. 
Compressed air and steam. 
Charges of mixtures. 
Gas Mgs to regulate supply. 
Rotatory engine and 

pumps. 
Enclosed crank chamber. 
Tram and vehicles. 

Hot air. 

Utiliaing heat after explo- 
sion. 

Combined gas and com- 
pressed air. 

Double piston, 

Lubricating. 

Igniting. 

Regulating. 

Thermodynamic enffine. 

Combined gas and oynamo. 

Hydrocarbon and valves. 
Valves and governing. 
Cylinders, governing and 



igniting. 
Cylini' 



Cylinders, valves and igni- 
tion. 



lease 
alves. 



Cylinder and vi 



Adjustable ports. 

Propelling by reaction of 
explosion. 

Low pressure or vacuum 
motor. 

Cylinders and valves. 

Valves. 

Petroleum. 

Air engine. 

Hot air and motive power. 

Oil for gas engine. 

Carburetter. 

Gas and steam. 

Piston, slides and govern- 
ing. 

Twin engines. 

Heating air. 

Generaldesign, andelectrio 
iniition. 

Valves. 

Ignition. 

Hydrocarbon. 

Cylinders and valves. 

Hydrocarbon. 

Cylinders and ignition. 

Varying expansion. 



LIST OF PATENTS. 



375 



Abel, . 
Priestman and 

Priestman, 
Lane, . 

Hearaons, . 
List and others, . 
Boolt,. 
M'Dowall, . 

Koerting, . 
Lea, . 
Knight, 

Davy 

Barker, 
Middleton, . 
Hutchinson, 
Schmidt and Beekfeld, 
Crossley and Anderson, 
Butler, 

I>avy 

Williams, . 



Speeiallty. 
12, 187 Sept. 8, 1887, Reservoir of gas and air. 



Ravel and Brecttmayer, 

Sturgeon, . 

Abel, .... 

Wallwork and 

Sturgeon, 
Bickerton, . 
Abel, . 



12,432 „ 13, „ Hydrocarbon. 

12.591 „ 16, „ Power to vehicles by com- 

pressed air. 

12.592 ,, 16, ,, Vaporising hydrocarbons. 
12,696 „ 19, „ Petroleum motor. 
12,749 „ 20, „ Oil and electric ignition. 
12,758 „ 20, „ Sight feed lubricators for 

eas engine. 

12,863 „ 22, ,, Valves and ignition. 

13,436 Oct. 4, „ Starting gaa engines. 

13,555 „ 6, „ Ignition for hydrocarbon 

engine. 

13,916 „ 13, „ Supply to motors. 

14,027 », 15, ,, Admission and ignition. 

14,048 „ 17, „ Varying stroke. 

14,269 „ 20, „ Jackets for vaporising oil. 

14,952 Nov. 2, „ Cylinders and valves. 

15,010 „ 3, „ iKuition. 

15,598 „ 15, ,, Hydrocarbon for vehides. 

15,658 „ 15, ,, Ou jacketed cylinders. 

16,029 „ 22, „ Cylinders and pistons. 

16,144 „ 24, „ Cylinders and ignition. 

16,257 n 26, „ Cylinders and valves. 

16,309 „ 28, „ Cvlmders and pistons. 

17,108 Dec. 12, „ Motor engineby gas, vapour^ 

or spray. 

17,353 „ 17, „ Governing. 

17,686 „ 23, „ Starting by water motor. 

17,896 „ 29, „ Ignition, tubes heated. 



SpxomoATioirB or Patents tiled fob Gas, Petroleum, and^ 
Hot Air Engines fob the Year 1888. 



Priestman and 
Prieetman, 

Rogers, 
Sington, 
Johnson, 
Abel, . 
Imray, 

Blessing, . 

Crossley, . 
Butler, 

Quack, 
Cole, . 

Windhauseu, 



270 


Jan. 


6, 


281 


99 


7, 


512 


,, 


12, 


600 


99 


H 


688 


99 


16. 


1,336 


99 


28. 


1,381 


99 


30, 


1,705 


Feb. 


4. 


1,780 


99 


6, 


1,781 


9* 


6, 


2,466 


9» 


18, 


2,467 


99 


18, 



2,549 



2I9 



8p«oUIIt7. 

Starting hydrocarbon 

engines. 
Compressed air. 
Gas and petroleum. 
Hot air. 
Igniting. 
Starting gas and tram 

engines. 
Hydrocarbon for tram 

engines. 
Compound gas or oil motor. 
Hydrocarbon. 

19 

Gas, vapour, or air. 
Cranks longer than cylinde r, 

gas and other engines. 
Expanding air and gases. 



376 




APPENDIX. 






Johnson, . 


2,804 


Feb. 


24, 1888, 


SpeoiAlity. 
, Cylinders and valves for 












admission and exhaust. 


II ... 


2,806 


it 


24. 


II 


Starting gear. 


Ochelhauser, 


2,913 


II 


27, 


II 


Rapid combustion in gas 


Abel, .... 


3,020 


II 


28, 


II 


engine. 
Gas, vapour, or air. 


,,.... 


3,095 


1* 


29, 


>> 


Igniting gas or oil motor 


M*Ghee aud Burt, . 


3,427 


Marcl 


I 6, 


I* 


engine. 
Governing and sun and 
planet motion. 


Rollason and 












HamlltoD, 


3,546 


II 


"> 


II 


Starting, governing, and 
reservoir. 


Oossley, . 


3,756 


II 


10, 


II 


Ignition and valves. 


Oaze 


3,964 


II 


H. 


II 


C'ompress gas and air and 
store separately. 


Turner, 


4,057 


II 


16, 


II 


Compressed air for motor. 


Bourne, 


4,631 


II 


24, 


II 


Hydrocarbon. 


Orossley, . 


4,624 


II 


26, 


f> 


Valves and governing gear. 


Wilaon, 


4,944 


April 


3, 


II 


Gas engine and producer. 


Lake,. 


5,204 


II 


7, 


II 


Ignition for gas and 
petroleum. 


Tavemier and Casper, 


5,628 


i» 


16. 


II 


Gas and steam. 


Humes, 


5,632 


II 


16, 


1* 


Hydrocarbon. 


Abel, .... 


6,724 


II 


17, 


II 


Petroleum. 


Rowden, . 


5,774 


II 


18. 


fl 


Increased efficiency of gas, 
&c., engines. 


Lake,. 


5,914 


91 


20. 


l« 


Hydrocarbon. 


<Gaze, .... 


6,036 


II 


23, 


II 


Compressing gas and air 


Thompson, . 


6,088 


11 


24, 


»l 


sei)arately. 
Production of carburetted 

nil* 


Wells and others, 


6,108 


II 


24. 


II 


air. 
Hot air motor. 


TelUer, 


6,212 


II 


26, 


II 


Producing cold by waste 

heat. 
Gas and air motor for 

vehicles. 
Hydrocarbon. 


Karylynski, 


6,468 


May 


1, 


>l 


Wordsworth, 


7,521 


91 


22, 


II 


Browett and Lindley, . 


7,547 


»> 


22. 


II 


Valves for hydrocarbon 


SchneU, . 


7,893 


>■ 


30. 


II 


engine. 
Hydrocarbon. 


Stubbs, 


7,927 


91 


30. 


II 


ff 


•Southall, . 


7,934 


>t 


30. 


II 


Cylinders, valves, and 
second shaft gas enj^ne. 


Nelson, . . . 


8,009 


June 


1. 


II 


Hydrocarbon and igniting. 


Johnston, . 


8,252 


*9 


6, 


f f 


Cylinders and pistons, gas 
or vapour. 


Kosztovito, 


8,273 


ff 


6. 


II 


Cylinders for gas or hydro- 
carbon and locomotives. 


De BoutteviUe and 












Malandin, 


8,300 


I* 


6. 


9t 


Starting. 


Altmau, 


8,317 


» 


7. 


fl 


Prevention of premature 
explosion in petroleum. 


De BoutteviUe and 












Malandin, 


9,249 


*l 


26, 


11 


Governor for gas and other 


Roots, 


9.310 


» 


26. 


fl 


engine. 
Piston and second explosion 
chamber. 


II ... 


9,311 


>■ 


26. 


if 


Generator to hydrocarbon. 



LIST OF PATENTS. 



377 



' Dougill, . 


. 9,578 


July 


29 


Abel, . . . 


. 9,602 


>) 


2. 


Knight, 


. 9,691 


t* 


4, 


Rawden, 


. 9,705 


1} 


4, 


Purnell, . 


. 10,166 


}, 


12, 


Nash, 


. 10,350 


>) 


17. 


Giffard, . 


. 10,645 


>i 


23, 


Binney and Stuart, 
Campbell, . 


. 10,667 


}, 


24, 


10,748 


t> 


25, 


Hargreaves, 


. 10,980 


»} 


30, 


, Piew.. . . 

1 


10,983 


f» 


30, 


,, . 


. 10,984 


>> 


30, 


Roots, 


. 11,067 


sy 


31, 


Morris and Wilson, 


. 11,161 


Aug. 


1, 


Barker, . 


. 11,242 




3, 


Pnrchas and Freund, 


11,614 


9} 


11, 


Ellis, . 


11,847 


»« 


16. 


Hargreaves, 


12,361 


)) 


28, 


■Charon, 


12,399 


)> 


28, 


Wells, . . 


13,206 


Sept. 


12. 


Boult, 


13,414 


>i 


179 


Stnart and Binney, . 


14,076 


Oct. 


I9 


Crossley and Holt, 


14,248 


19 


3, 


Abel, . 


14,349 


II 


59 


Hearsons, . 


14,401 


»» 


6. 


Royston, . 
Wiliams, . 


. 14,614 
. 14,831 


t9 


11, 
16, 


RichardB, . 


15,158 


9} 


22, 


Thompson, . 


15,448 


»» 


27, 


Bonlt, 


15,840 


Nov. 


2, 


tt . . , 


15,841 


») 


2. 


»» • • 


. 15,845 


9* 


2, 


It . . . 


15,846 


»J 


2, 


Jensen, 


. 15,858 


Jt 


2, 


I Roots, 


15,882 


9« 


3. 


Lindley and Browett, 


16,057 


»> 


6. 


Simon, 


. 16,183 


99 


8, 


Roots, 


16,220 


99 


9. 


Lalbin, 


16,268 


If 


9. 


Menzies, . 


. 16,605 


9> 


15. 


Koerting, . 


. 17,167 


99 


26, 


Schmidt, . 


. 17,343 


99 


28, 


Orossley and Anderson 


, 17.413 


99 


28, 


Shaw, . . 


. 18,377 


Dec. 


17, 


Davies, 


. 18,516 


99 


18. 


Nichols, . 


. 18.707 


99 


2I9 


Hargreaves, 


. 18.761 


99 


22. 


Pinkney, . 


. 19,013 


>9 


29, 



Speciality. 
1888, Timing motion of valve 

for admission, &c. 
„ Valve for gas or hydro- 
carbon. 
Hydrocarbon. 
Arrangement of cranks. 
General design. 
General design and ignition. 
Compressed air motor. 
Hydrocarbon. 
General design. 
Combustion thermometer. 
Hot air, compressed do.,and 

gas for tram loco. 
Starting tram loco., with 

air, gas, &c. 
Hydrocarbon. 
Generator for gas and 

hydrocarbon. 
Valves and governing. 
Hydrocarbon. 
Hot air, gas, or steam. 
Thermoraotors. 
Variable expansion and 

igniting. 
Hot air. 
Cylinders, pistons, valves, 

and cranks. 
Hydrocarbon. 
Starting. 

Ignition, gas or oil 
Charging and ejection of 

spent charges. 
Heat engine, 
(voveming. 
Hydrocaroon. 
Carburetter to gas engine. 
Petroleum. 
Ignition. 

Keeping walls cool. 
Friction cluteh for gas 

engines. 
Braking and restarting. 
Sterting petroleum engine. 
Hydrocarbon. 
Cylinder and pisten. 
Governing and starting. 
Multiple cylinder and 

ignition. 
Pisten rings. 

Valve for gas or |)etroleum. 
Steam and air. 
Ignition, oil or gas. 
General design. 
Utilising waste heat of gas 

engine. 
Obtaining variable speed. 
Thermometer. 
General design. 



378 



APPENDIX. 



SPBGinCATION OF PATENTS FILED FOB QaB, PeTBOLEUM, Ac, EmGIVES 
FOB THE YeAB 1889. 

Speclmlltr. 



Boult, . . 


121 


Jan. 


3, 1889, Distributing mechaninn. 


Robmson, . 


298 


99 


8, 


,) 


Hot air. 


Paton, 


441 


>» 


10, 


*t 


SUrting. 


Taylor, 


. 708 


it 


15, 


J» 


Double cylinder, and 

general design. 
S^nd cylinder for charge. 


Repland, . 


. 876 


91 


17, 


>> 












greater volnme. 


WftllR, 


. 1,593 


tt 


29, 


»f 


Hot air, combination cylin- 
der and chamber. 


Tavernier and 












Schlesinger, . 


. 1,603 


t1 


29, 


ti 


Hydrocarbon, jacketed 

cylinder. 
Slide valves for gas en^es. 


ThompBon, . 


. 1,831 


Feb. 


1, 


i* 


Peebles, . 


. 1,957 


•> 


4. 


>> 


Double-acting gas engine. 


Ketchem, . 


. 1,977 


.. 


4, 


f» 


Qeneration of steam and 


Field. . 


. 1,997 


f f 


4. 


f 1 


gases. 
Hotair and gases. 


Piers, . 


. 2,144 


f> 


6, 


>» 


Locomotion by gas or 
petroleum. 


Davenport and 












Horsley, . 


. 2,587 


» 


u, 


f > 


Pistons for gas engines. 


Miller, 


. 2,637 


t* 


H, 


»» 


Petroleum vapour or gas, 

general desiflrn. 
Gas en^ne and generator. 


Gardie, 


. 2,649 


»t 


14, 


>» 


Adams, 


. 3,331 


t» 


25, 


St 


Explosion reservoir. 


Pinkney, . 


. 3.526 


•> 


27. 


tt 


Working gear of gas 

engines. 
Double-acting gas engines. 


WilUams, . 


. 3,820 


March S, 


tt 


Roots, 


. 3,972 


»* 


6, 


tt 


General improvements. 


Schmidt, . 


. 4,237 




H. 


tt 


Mixed steam and gas 
motors. 


Phillips, . 
Von Ochelhauser, 


. 4,302 




12, 


tt 


Hot air. 


. 4,710 


tf 


18, 


tt 


Ignition of variable mixture 












of gas. 


SchemmingB, 


. 4,796 




19. 


tt 


Sunerheating steam, by in- 
flammable gas. 


Southall, . 


. 6,072 




23. 


tt 


Oil or fras combination, 
reservoir and cylinder. 


Lake, . 


. 5,165 




26, 


>> 


Propulsion of vessel by ex- 
plosion en^ne. 
Propulsion of vehicles and 












Millet. 


. 5,199 




26. 


It 












aerial do. by gas engine. 
Charging cylinder, gas. 


Theevman, . 


. 5,301 




28, 


tt 












vapour and hydrocarbon. 


Nelson and M'Millan, 


. 6,397 




29, 


tt 


Vslves and governing. 


Abel, . 


. 5,616 


April 


2. 


tt 


Reversing mechanism. 


Binki and Csonki, 


. 6,296 




12. 


tt 


Valve motion. 


Priestman and 












Priestman, 


. 6,682 




18, 


tt 


Hydrocarbon. 


Cordenons, . 


. 6,748 




20. 


l» 


Rotatory gas, petroleum, or 



Knight, 



steam. 

6,831 „ 24, „ Vaporiser for engines by 
oil. 



LIST OF PATENTS. 



379 



Tavemier and Casper, 

TeUier, 

Sumner, 

>» ... 

Crowe and Crowe, 

Sergeant, . 

LawBon, 
Weatherhogg, 

Imray, 

Clerk, 

Lake, . 
BatJer, 



Roots, 

Daimler, 

Wells and Clarke, 

Rogers and Wbarry, 

Rowden, 

Leigh, 

Wastfield, . 

White and Raphael, 
Williams, . 
Hartley, 

Dheyne, 

Bnll, . 

Allison, 

Hoelljes, 

Thompson, . 

Lanchester, 

Middleton, . 

M'AUen, . 
Bennett, 

Huntington, 
Hargreaves, 



Speciality. 
7,069 April, 27, 1889, Cooling, cylinder of gas 

engine. 
7,140 „ 29, „ Producing combustible 

gases for power. 
7,522 May 6, „ Ignition by electricity. 
7,533 „ 6, ,, Ignition by incandescent 
platinum. 
Gas or hydrocarbon. 



7.694 „ 

7,605 „ 

7,640 „ 
8,013 

8.778 „ 

8,805 

8,886 
9,203 June 



Hunt and Howden, . 9,685 



9,834 „ 

10,007 „ 

10,144 „ 
10,286 

10,634 July 

10,669 

10,831 

10,850 

11,038 
11,162 „ 
11,395 „ 

11,459 

11,926 



7, 

7. 

7. 
14, 

27. 

28, 

28, 
3. 

12, 

15, 
18, 
21, 
24, 
1, 

2. 

6, 

5, 

9, 
11, 
16, 

17, 

26, 



SBneral design. 



12,045 „ 30, 

12,447 Aug. 6, 

12,472 „ 7, 

12,502 „ 7, 

13,431 „ 26, 

13,572 „ 28, 

14,154 Sept. 7, 



14,592 
14.789 



17, 
19, 



klves for steam and air 
engines. 

General design. 

Petroleum and general 
design. 

Supplying petroleum to 
engines. 

Double piston for gas 
engines. 

Hot air. 

Multiple cylinder. Petro- 
leum. 

Reaction wheel, by com- 
bustible gas or vapour. 

Hydrocarbon. 

Gas and petroleum motors. 

Hot air. 

General design. 

Petroleum or other explo- 
sive generator. 

Link connection for gas 
engines. 

Compound gas or petro- 
leum. 

Petroleum or other hydro- 
carbon. 

General desi|;n. 

Tube for igniting. 

Hydrocarbon vaporiser 
and air heater. 

Generating gas from com- 
bustible liquid. 

Admission passages and 
valves for gas, air, or 
vapour. 

Combined carburetter and 
gas engine. 

Methods of operating gas 
engines. 

Combination of cyluider 
and ^umps. 

Govemmg, gas and other 
motive power. 

Gas and steam power tri- 
cycle. 

Gas or oil motor. 

Motive power from carbonic 
oxide. 

Vehicles, by vapour engines. 

Thermomotor. 



380 




APPENDIX 






Binney and Stuart, 


. 14,868 


Sept. 


20,188S 


Speciality. 
, Hydrocarbon. 


Diederichs,. 


. 14,926 


>i 


21, 


99 


Combustible vapour engine. 


WiUcox, . 


14,927 


»» 


21, 


fl 


Hot air. 


M'Tighe, . . 


. 15,805 


»f 


24, 


»» 


Conversion of heat into 
motive power. 


Sparway, . 


. 15,295 


»» 


28, 


»> 


Hot air and other gas. 


Oreen, 


. 16,202 


Oct. 


15. 


)l 


General arrangement. 


Lmdemann, 


. 16,391 


»» 


17, 


»l 


Valve arrangement. 


Hamilton and 












Bollason, 


. 16,434 


*) 


18, 


>) 


Gas or vapour, general 

design. 
Combined gas, and steam 


Haedicke, . 


. 17,008 


>i 


28. 


>f 












engine. 


Boalt,. 


. 17,024 


ii 


28, 


• f 


Petroleum. 


Niel, . . . 


. 17,296 


»> 


31, 


»♦ 


Valves, ports, governing 
and lubricating^. 


Lowne, 


. 17,344 


Nov. 


1. 


99 


Atmospheric engme. 


Abel, . 


. 18,746 


>} 


22. 


M 


Igniting gas or oil motor 


Schmidt, . 


. 1^,813 


it 


23, 


)» 


engme. 
Steam and air motors. 


Barrett and Daly, 


. 18,847 


»i 


23, 


»» 


Electric igniter. 


Schmidt, . 


. 19,124 


» 


28, 


f» 


Combined steam and hot 

nil* 


Lanchester, 


. 19,868 


Dec. 


10. 


II 


air. 
Valves and governing. 


Lindley and Browett, 


. 20,033 


»♦ 


12. 


»» 


Hydrocarbon. 


Ford, . 


. 20.115 


/» 


13. 


• I 


Rotatory gas engine. 


Duerr, 


. 20,161 


f » 


u. 


>l 


Gas or petroleum motor. 


Frederking and 












Schubert, 


. 20,166 


»> 


14, 


»l 


Valve gear for gas, steam, 

&c. 
Igniters and general 


Crist and Covert, 


. 20.249 


99 


17, 


*l 












design. 


Atkinson, . 


. 20,482 


l» 


20, 


II 


Internal combustion heat 


Clark. 


. 20,612 


}> 


20, 


»> 


engme. 
Throttle valve for gas and 
other engines. 


Snelling, . 


. 20,703 


M 


24, 


II 


Rotatory gas, steam, or air 


Jenks, 


. 20,748 


»f 


24, 


II 


engine. 
Governors for gas and other 


Abel, . . 


. 20,892 


»> 


30. 


II 


eneines. 
Reflating speed of gas or 
oil motors. 



Specification or Patents filed for Gas, Petroleum, and 
Hot Air Engines for the Year 1890. 

SpedaUtr. 
Jan. 3, 1890, Air motor. 
,. 16, „ Compressed air and com- 
bustible fluid. 
„ 21. ,. Metallic packing. 
„ 22, „ Petroleum, general design. 
„ 29, „ Cylinders and pistons. 
Feb. 6, „ Petroleum, general design. 
„ 11, „ Regulating gas supply. 



Mewbum, . 
Mannesman, 


132 
837 


Bedford and Rodger, . 

Linder, 

Tavemier, . 

Abel 

Soollary, . 


1,064 
1,160 
1,686 
1,943 
2,207 



LIST OF PATENTS. 



381 



Tonche, 


. 2,384 


Feb. 


13, 


Lake, . 

,, • • . 
Orob and others, 


. 2,647 
. 2,648 
. 2,914 


»» 


18. 
18. 
24. 


Mnnden, . 
Abel, . 


. 3,128 
. 4,164 


,. 27, 
March 17, 


Binnsy 


. 4,362 


>« 


20, 


Kaselowsky, 


. 4,574 


»» 


24. 


Otto, . 


. 4,823 


1) 


27. 


Baxter, 


. 5,005 


»» 


31, 


MelniBh, . . 


. 5,192 


April 


3. 


Otto, . 


. 5,273 


»f 


6, 


„ . . • 


. 5,275 


»» 


6, 


Lanchester, 

Mayer, 

Dheyne and others. 


. 6,479 
. 5.787 
. 5,933 


»» 


10, 
16. 

18. 


Otto, . 
Hamilton, . 


. 5.972 
. 6,016 


«> 
»» 


19, 
21, 


Otto, . 


. 6,113 


»> 


22, 


Griffin, 


. 6,217 


>* 


23, 


Dawson, 


. 6,407 


»» 


26, 


Donington, . 


. 6,910 


May 


5, 


Fielding, . 
Butler, 


. 6,912 
. 6,990 


»♦ 


6. 
6. 


Stuart and Binney, 


. 7.146 


»i 


8. 


Mewbum, . 


. 7,177 


>i 


8, 


Johnson, . 


. 7.626 


11 


16, 


Sykes and Blamiris, 


. 7,830 


>» 


20, 


Popp, . 


. 8,322 


)» 


29, 


Seage and Seage, 
Robson, 


. 8,431 
. 9,496 


June 


31, 
19. 


Butterfield, 
Wilkinson, . 


. 9,769 
. 10,051 




24. 

28, 



SpcMpIallt^. 
im ignitin^ 
liquid petroleum. 



Beechey, . 



10,089 



30, 



Combination of cylinders. 

Air engine. 

Petroleum motor, air to 

inlets. 
Speed varying gear. 
Governing, gas and 

petroleum. 
Additional cylinders, 

pistons, and ignition. 
Petroleum and gas, inlets 

and ignition. 
General improvement for 

regular working. 
Gradual mixture outside 

cylinder. 
Gas and petroleum, com- 
pound engine. 
Kegulatiog gas or oil 

motors. 
Mixture of atmospheric air 

and of oil 
Starting. 

Cylinders and pistons. 
Petroleum and gas, general 

design. 
Ignition and regulating. 
Gas or vapour motor, 

general design. 
Supplementary cylinder, 

piston, and valve. 
Combustible gases for 

motors. 
Reciprocating and rotatory, 

no vcdrett. 
Double cylinders, position 

and ans;le of. 
General design. 
Hydrocarbon, general 

design. 
Vaporiser direct to 

cylinder. 
Combined gas and com- 
pressed air motor. 
Engine, sector of sphere, 

and separate chamber for 

combustion. &c. 
Conversion of solid into 

gaseous fuel. 
Compressed air motor and 

heating stove thereof. 
Lever, gear for valves. 
Double pistons, unequal 

strokes. 
Lubricators. 
Producing carburetted air 

for motors. 
Piston valves. 



382 

Williams, . 
Stuart, 

Vogelsang and Hille, . 10,642 



Grob, Shutze, and 
others, . 



APPENDIX. 

Spedftlity. 
10,137 July 1, 1890, Obtaining motive power 

by explosion. 
10,293 ,, 3» I, Obtaining power from 

ammonia and compressed 
air. 
9, „ Valve gear for petroleum 
and gas engines. 



10.718 

Griffin, . . . 10,952 

Lak 11,062 

Wells and others, . 11,174 

Richardson and Norris, 11,755 

Schiersand, . . 11,834 

PolUtt, . . . 12,111 

Holt 12,314 

Stuart, . . . 12,472 

M'Ghee and Burt, . 12,690 

Justice, . . . 12,678 

Stallairt, . . . 12,760 

Vermand, . . 13,019 

Stuart, . . . 13,051 
Ovens and Ovens, . 13,352 
Offen,. . . 13,594 

HaU 14,382 

Roots, . 14,549 

Robinson, . . 14,787 

De Boutteville and 

Malandin, . 14,900 

Redfem, . . 15,063 

Hartley, . . . 15,309 

Vivian, . . . 15,479 

Dheyne and others, . 15,525 

. 15,526 

Campion and Woods, . 15,807 

Stuart and Binney, . 15,994 

Cruickshank, , . 16,301 
Pinkney, . . . 17,167 



10, „ Ignition of gas, petroleum, 
and vapour engines. 

14, „ Valves for regulating and 
governing. 

15, „ Hydrocarbon, general 
design. 

17, »» Recovery of heat from 
steam and hot air. 

28, „ Ignition and other vslves 
for gas or vapour. . 

29, „ Governor. 

Aug. 2, „ Converting heat into 
mechanical energy. 
6, „ Supply, exhaust, and 

governing oil motors. 
9, „ Compound, hydrocarbon, & 
reciprocating cylinder. 
,, Collapsible reservoir, 

governing and igniting. 

13, „ Motor, general, for road 
and tram cars. 

14, „ Charging device, fiilminate 
for ignition. 

19, ,, Compression of air in 
special cylinder. 

20, „ Rotatory engine. 
25, „ Ignition, valves, and cooling. 
29, ,, (x>mbination of cylinders 

and pistons. 
Sept. 12, „ Ignition. 

16, „ Double explosion, second 
explosion chamber. 

19, „ Operating, valves. 



Oct. 



20, „ Governing, regulating, and 

valves. 
23, „ Hot air, high pressure. 
27, „ Hydrocarbon vaiK>riser. 
30, „ Hot air, general desigp. 
1, „ Copper and nickel, coils in 
connection with gas, &o., 
engines. 
1, ,, Conversion of liquid hydro- 
carbon into ffas. 
6, „ Utilisation and combustion 

of hydrocarbon gases. 
8, „ Chamber highly heated for 

ignition. 
14, „ General design. 
27, „ Gas or petroleum, general 
design. 





LIST OF 


PATENTS. 


Mattershea^, 


. 17,299 


Oct. 


29,1800. 


Higginson, . 


. 17,371 


>> 


30, „ 


Sayer, 


. 18,161 


Nov. 


11, „ 


Griffini 


. 18,401 


» 


14. ,. 


Boult, 

Kaaelowskjr, 

Lanchester, 


. 18,645 
. 19,171 
. 19,513 




18, „ 

26, „ 

I, „ 


Roots, 


. 19,669 


>, 


1. .. 


Lobet, 


. 19,791 


I, 


4, „ 


Griffin, 


. 19,962 


,t 


6, ., 


Albrecht, . 


. 20,226 


1, 


11, ., 


Holt, . 


. 20,888 


>> 


22, „ 


Lentz and others, 


. 21,165 


*» 


29, „ 



383 

Speciality. 
29, 1890, Compound cylinder, hollow 

valves, combining pas- 
sages and ignition, &c. 
Loose piston controlled by 

compressed air. 
Gaseous pressure, apparatus 

for producing motion. 
Igniting in hyarocarbon or 

petroleum. 
Governors. 
Igniting devices. 
Ignition and starting, gas 

or hydrocarbon. 
Prevention of leakage in 

petroleum, &c. 
Distributing device for 

valves. 
Forming combustible spray 

of air and finely divided 

hydrocarbon. 
Gas generator and motor 

combined. 
Water jacket and tank for 

uniform temperature. 
Single acting engine, 

general design (novel). 



Specifications of Patents filed fob Gaf, Petboleum, and Hot Air 
Engines fob the Year 1891. 



Pinkney, . 


103 


Jan. 


2. 


Carling, . 


110 


j» 


3, 


Gray, . . . 


191 


>* 


6, 


Bickerton, . 


. 227 


»» 


6, 


Bickerton, . 
Boult, 


. 297 
383 


ft 

9> 


7, 
8. 


Kehlberger and 

Fougue, . 
Adams, 
MacCallum, 
Miller, 


458 

741 

. 816 

. 834 


>» 

>> 
If 


9. 
15, 
16. 
16, 


Williams, . 


970 


» 


20, 


Robinson, . 
WilUams, . 


. 1,083 
. 1,299 


*> 


21, 
24, 



Spectalitr. 

2, 1891, Position of valves, and igni- 
tion, hydrocarbon. 

Governing gas and other 
engines. 

Producing explosive mix- 
ture, hydrocarbon. 

Prevention of noise by in- 
take of air. 

Governing. 

Valve gear for gas or i»et- 
roleum. 

Areo-hydro-thermo engine, 
llotatory engine. 
Heat engine fluid piston. 
Petroleum vaporiser and 

cylinder combined. 
Combination of cylinder, 

piston and valves. 
Governing. 
Timing openiug, &c., of ig- . 

nition valves and starting. 



384 




APPENDIX. 


Weatherhogg, . 
Abel, . 


. 1,447 
. 1,903 


Jan. 
Feb. 


27, 189 
2, „ 


Gray, . 
Rouzay, 


. 2,053 
. 2,815 




4. .. 
16, „ 


Hughes, 


. 2,976 


ft 


18, „ 


Weiaa, 


. 3,261 


»t 


23, ,. 


Coffey, 
Rockhill, . 


. 3,350 
. 3,669 


It 


24, .. 
28, „ 


Wertenbrach, 


. 3,682 


»> 


28, „ 


Priestman and 
Priestman, 


. 3,830 


March 3, ,, 


Trewhella, . 


. 3,948 


»» 


5, ., 


Dawes, 
Fenby, 


. 4,004 
. 4,024 


»» 


6. ,. 
6. ,. 


Priestman and 
Priestman, 


. 4,142 


If 


7. „ 


Lanchester, 
Campbell, . 


. 4,222 
. 4,355 


»« 


10. „ 

11. ,. 


Griffin, 
Cooper, 
Vanduzen, . 


. 4,535 
. 4,771 
. 6,158 


it 


13. .. 

17. „ 
23, „ 


Love and Priestn 


lan, . 5,250 


>» 


24, „ 


Higginson, . 
Fachris, 


. 5,490 
. 5,663 


April 


28, „ 
1. .. 


Skene, 


. 5.747 


»» 


3, .. 


Bickerton, . 
Day, . . 


. 6,090 
. 6,410 


f » 
tt 


9, ., 
14, „ 


Barclay, 


. 6,578 


»» 


16, „ 


Ridealgh and We 


Iford, 6,598 


»» 


17, „ 


Abel, . 


. 6,717 


»» 


18. ,. 


Rennes, 


. 6,727 


,, 


18. .. 


Key, . . . 
Pumell, 


. 6,949 
. 7,047 


it 


22. „ 

23, „ 


Altman, 
Pinkney, . 


. 7.157 
. 7,313 


it 


25, „ 

28, „ 



Hpeciality. 
27, 1891, Hydrocarbon vaporiser. 

Valves for gas and petro- 
leum engines. 
Vaporiser for hydrocarbon. 
Gas and petroleum, general 

design, 
liotatory, three cylinders 

rotate. 
Production of combustible 

vapour from petroleum, 

&c. 
General design 
Flywheel guards for gas 

engines. 
Pistons, double movable 

rings. 

Admission of cold air to 

heated charge. 
Utilisine residue of gases 

exploded. 
Starting. 
Valves for hydro and fluid 

pressure machines. 

Elydrocarbon separating 
jacket into two parts. 

Governing by use of magnet. 

Distributing combustible 
mixture. 

Regulating and governing. 

Ignition. 

Gas and gasoline engine, 
general design. 

Using liquetiable gas for 
cooling jackets. 

Treble cylinder. 

Explosive engine, by 
powder, ''Gatling" 
system. 

Anti-fluctuator and regula- 
tor for gas, &c. 

Igniting and starting. 

Kudosed crank, and im- 
pulse every revolution. 

Double-acting, cylinder 
closed each end. 

Simple gas engine, general 
design. 

Supplying oil, &c. , at con- 
stant pressure. 

Petroleum motor, for road 
cars, &c., 

Discharge of gases. 

Governor for gas or oil 
motor. 

i» »» 

Conical combustion, 
chamber and ignition. 





LIST OF ] 


PATENTS. 


Horn, . 


. 8,032 


May 


9,1891 


Capitaine, . 


. 8,069 


>> 


11. 


*» 


Barrett and Ticehurst, 8,251 


)> 


14. 


St 


Abel,. .' 


. 8,289 
. 8,469 


•» 


14, 
16, 




ShilUto, . 


. 8,821 


>> 


26, 


»> 


Boult, 


. . 9,006 


tf 


27, 


» 


Southall, . 
Day, . . 


. 9,038 
. . 9,247 


Jnne 


1: 




Bosshardt, . 
Huesler, 


. 9,268 
. 9,323 




2, 
2, 




Hawkina, . 
Withers and Gov 
Croealey and Hoi 


. 9,805 
crt, . 9,931 
t, . 10,298 




10, 
11. 
17, 




Fiddes and Fiddc 
IrgeoB, 


», . 10,333 
. 11,132 




18, 
30, 


>• 

n 


Pinkney, . 


. 11,138 


>i 


30, 


99 


Held, . 


. 11,628 


July 


8, 


99 


Kaselowsky, 


. 11,680 


>i 


9, 


)S 


Wellington, 
Lanchester, 
SetUe, 


. 11,851 
. 11,861 
. 12,330 


>* 


13, 
13, 
21, 


♦ ♦ 


aerk,. . 
Menard, 


. 12,413 
. 12,981 


•> 


22, 
31, 


>> 


King, . 


. 12,981 
. 14.002 


Aug. 


31, 
19, 




Weyman and Dr< 


)he, . 14,133 


»• 


21, 


>> 


Watkinson, 


. 14,134 


» 


21, 


>f 


Haelser, . 


. 14,269 


f> 


24, 


» 


Abel, . 


. 14,519 


>» 


27. 


l> 


Hoffinan, . 
Lancheater, 
Waiiama, . 
Clerk,. 
HomsbyandEdT 


. 14,865 
. 14,945 
. 15,078 
. 16,40i 
wda, 17,073 


Sept. 
>» 

»* 
Oct. 


2; 

t 

28, 
7, 


»> 
»> 
>> 
»» 



385 

SpeolAlitr. 
, Simple gaJs engine, general 

design. 
Combination of valves to 

inlet 
Starting gas engine by 

cartridges of explosives. 
Rotatory gas engine. 
Drawing in and expelling 

air for expansion. 
Igniting tube for petroleum 

motors. 
Improved gas or petroleum 

engine, general design. 
Valves for charging, &c., 
Simple gas engine, run 

either way. 
Governors and valves. 
Gasifying contrivance for 

petroleum motors. 
Vibrating gas engine. 

tt >» 

Begulating supply of oil to 

oil motors. 
Second piston at back end. 
Petroleum and gas motor 

and producer. 
Petroleum combustion and 

igniting chamber. 
Gas pressure regulator for 

engines. 
Valve motion, petroleum 

engine, and generator. 
Imperishable igniting tube. 
Starting gas motors. 
Boat or tram propulsion by 

gas. 
Operating valves. 
Firing charges by magne- 
tism, dynamo, and 

Rhumkorff coiL 

Cylinders, pistons, igniting 
and exhausting mechan- 
ism. 

Regulating supply of oil to 
hydrocarbon. 

Improvement in thermo- 
dynamo machine for gas, 
&a, motors. 

Link motion for opening 
valves. 

Igniting apparatus for oil 
or gas. 

Hot air, general design. 

Governors. 

Starting. 

Valve details. 

Mixing hydrocarbon with 
air, pefroleum motor. 
25 



386 



APPKHDIZ. 



Bwra. 

Abel, . . 


• 


17,364 
17,724 


Oct. 


12. 
16, 


£VBIU» 


. 


17,815 


If 


17, 


PinkjMjy 


• 1 


17,965 


» 


20, 


Shaw and Asworth, . 


18,020 


>f 


21. 


Walch, DarringfcoQ, and 

others, • 
Field,. . . . 


I 
18,276 
18,603 




2$' 
27, 


Roots, 


• • 


18,621 


»f 


2». 


Weymanand 


others, . 


18,640 


j» 


29. 


Earnshaw and others, 

aerk,. 

Roots, 


18,716 
18,788 
19,275 


» 


30, 
31, 

7. 


Barron, 


• • 


19,318 


>f 


9. 


Fielding, . 
Johnson, . 




19,617 
19,772 




11, 
14, 



Ridealgh, 



19,773 



19,811 



Robinson, . 


. 20,262 „ 


21. 


»> 


. . 20,745 „ 


28, 


Perrollas, . 


. . 20,845 „ 


30, 


Knight, . 


. 20,926 Dec. 


1. 



Weyman and others, . 21,015 



1 mnvnwmft 


or. 


• 2X,^ftUO 


>» 


Of 


>> 


Hartley and Kerr, 
MiUer, . . 


. 21,496 
. 21,629 




9, 
9. 




Leigh, 


. 


. 22,669 


>f 


24, 


» 


Bi^ . 


• 


. 22,669 
. 22,67a 




24, 
28, 


tf 
ff 


Seek, . 


. 


. 22,834 


tt 


31, 


>» 


Abel, . 


• 


. 22,847 


» 


31, 


t» 



Speciality. 
12, 1891. Automatic valves. 

Valve apparatus control- 
line charges, Ac 

Simple gas engine, rotatory 
valve. 

Igniter for gas or petroleum 
engine. 

Better utilisation of pres- 
sure in gas engines. 



Valve gear. 

Improvement of engine 
worked by hot gases, such 
as air, &c. 

Valve gear for internal 
combustion engine. 

Prevention of overheating 
in gas engines. 

Valves of gas engines. 

Starting gear. 

Improvement in hydro- 
carbon, &c., engines. 

Conversion of slide gas 
en^es to tube igniters. 

Starting. 

Feed pumps for petroleum 
engme. 

Means to regulate tempera- 
ture of evaporation in 
petroleum engine. 

Sealed chamber and flexible 
partition in gas or 
petroleum motors. 

Qas engine, general design. 

Gas engine, cooling. 

Lubricators for gas engine. 

Vaporiser for petroleum 
and heavy hydrocarbons. 

Ignition, cooling, and 
vaporiser for hydro- 
carbon. 

Operating valves and 
governing. 

Governing gas engine. 

Valve gear, speciidly 
exhaust. 

Utilisation of gases before 
expelled from cylinder. 

Starting, stopping, and 
reversing gas and vapour 
engines. 

Simple gas or hydrocarbon 
engine. 

Combination of vaporiser 
and explosion chamber of 
hydrocarbon and oil 
motors. 



14, 



16, 



2, 



LIST OP PATSNT8. 



387 



SpxcinoATiOKs or Patents fiusd fob Gas, Petaoleum, aitd 
Hot Air Engines for the Year 1892. 

BpMUtlitr. 



Biohjurdson and Korrisy 112 Jan. 

Edwards^ ... 260 „ 

Krank, ... 435 „ 

Higginson, . . . 520 „ 

Wilkioaon,. . . 524 „ 

Rankin and Rankin, • 826 ,, 

Sinum, . . . 028 „ 

Thompson, . . . 1,075 „ 

Southall, . . . 1,203 „ 

Brooks and Holt, . 1,246 „ 



RiofaardaonandNonii, 1,768 „ 

Sohwar^ • . • 1,814 „ 
Barker, . . . 1,879 Feb. 



Atkinson, 

f» • • . 

Swidenkiy • • • 

^^oei, • • • • 

Leig^ • • • 

Crossley and Biad]egr» 

Jonstone, • 

Hanria^ 

Pinkner, • • • 
Ciwrmak, • 



2,181 
2,492 
2,495 
2,728 
2,854 



3,047 

3,165 

3,203 
3,292 



HmnpndgeandSnaiall, 3,417 
Robert, • * 3,574 

StaartandBbmey, * ^909 



4, 1892, Starting gas and vapour 
6, 



8, 

11. 

11, 

16, 

16, 

19, 

•21, 

22, 

29, 

29, 
1, 
4, 

9, 

9, 

11, 

13, 

13, 

16, 

18, 

18, 
19, 

22, 

23. 

29, 



en^es. 
Heating nnifocmly mixtnreB 

of air and pa. 
Utilisation of air or other 

gas for power. 
Double piston explosion 

between. 
Mixing vapour of bensoline 

with coal gas. 
Hydrocarbon mixing and 

vaporising. 
Starting gas or petroleum 

engines. 
Controlling power of 

engine. 
Disoharge vaWe for gas or 

oil motor. 
Water jacket of gas and 

vapour engine. 
Valve and operating valves 

of pa and vapour engine. 
Startmg and storing power. 
Gas bags for gaa encines. 
Self starting pa ana 

vapour engme. 
Internal combustion 

engine, general design. 
Distribution of inflam- 
mable vapour and air. 
Operating valves for regu- 
lating gas and oil motors. 
Supplymg liquid hydro- 
carbon, igniting, and 

governing. 
Starting and igniting gas 

or oil motors. 
Oscillating cylinder, gas or 

oiL 
Tubes for igniting gas or 

petroleum. 
Starting large gas engines. 
Single acting, cooled by 

Lubricating and starting 



flas engme. 
Cylind " 



Bickerton, 
Hamilton, , 



4,078 March 2, 



nder divided in three 

compartments. 
Regulating temperature of 

vaporiser of hydro* 

carbon. 
Governor.. 



4^189 



3, „ Valves and governing. 



388 






APPENDIX. 


Lftnchetter, 


• 


4,210 
4,374 


Marcb 
II 


I 3,1892. 
6, „ 


Riehardflon and KorrU, 


4,376 


II 


6, .. 


Clerk, 
BUbault, . 




5,445 
6,740 


i> 
II 


23, „ 


MichelB, . 




6.819 


II 


24, „ 


Owen, 




6,240 


II 


31, „ 


Chatterton, 




6,284 


April 


1, „ 


Morani, 




6,655 


II 


6. » 


Adams, 




6,828 


II 


9. „ 


ShiUito, . 




6,872 


II 


9. .. 


Courtney, . 




7,047 


II 


12, „ 


Diesel, 


• • 


7,241 


II 


14. „ 



Sennett and others, 
Homaby and others, 



7f943 „ 27, „ 
8.128 „ 29, „ 



Pollock, . 


. 8,401 


May 


4, 


II 


Beugger, . 


. 8,538 


II 


6. 


II 


Guillery, . 
Kobinson, . 
Beugger, . 


. 9,121 
. 9,161 
. 9,439 


II 
II 
II 


13, 
14, 
18, 


II 
1* 
II 


Richert, . 


. 10,019 


ff 


26, 


II 


Holt, . . 


. . 10,437 


June 


1, 


II 


Hcrsey, . 


. 10,639 


II 


4, 


II 


CKelly, . 
Snsini, 


. 11,598 
. . 14,711 


II 

Aug. 


21, 

le. 


II 
II 


II • 


. . 14,712 


II 


15, 


II 


Brigg, 


. . 14,713 
. 16,365 


11 
Sept. 


15, 
13. 


II 
II 


Redfeni, . 


. . 16,413 


II 


13, 


II 



BpecUlity. 
Goyeming and igniting. 

Operating valves and 

governing. 
Oil supplying for petroleum 
and liquid fuel engines. 

Governor and valve gear. 

Gas and petroleum, general 
design. 

Feeding devices for 
petroleum motors. 

Gas and hydrocarbon, 
general design. 

Method employing steam 
and gas for motors. 

Mechanism for distribution 
and mixing air and eas. 

Rotatory for steam, air, or 
gas. 

Petroleum motor, valves 
and vaporiser. 

Petroleum motor, supply 
of air and valves. 

Producing motive work by 
heated air, combustion 
of gases, or mixture of 
same. 

Utilisation of steam and 
gases for obtaining 
power. 

Piston, cylinder, heating 
air, and jacketing valve 
box. 

Governor and trip 
mechanism. 

Cooling, gas or hydro- 
carbon engine. 

Rotatory. 

Governor and mixing valve. 

Portable, gas or petroleum 
motor. 

Heating air to increase 
energy of same in air, 
&c., eneine. 

Igniting for gas or oil 
motors. 

Producing gas for motive 
power from decomposi- 
tion of ammonium, ni- 
trate, and a hydrocarbon. 

Tram car gas motor. 

Motor bv ether or other 
volatile liquid. 

Motor by ether in com- 
bination with steam. 

Motor by ether vapour. 

Lubricator for gas, &c., 
engine. 

Hot air motor, general 
design. 





DB. SLABT's ] 


BXPERIHE 


WhitUker, 
Fairfax, . 


. 16,980 
. 17,391 


Sept. 


23.1892. 
29, „ ] 


Held, . . 


. . 17,632 


Oct. 


4. „ . 


Southall, . 
Strok, 


. 18,109 
. 18,808 


>* 


11. ,. < 
20. .. 


Mein, . • . 
Enger, 


. 19,054 
. . 21,475 


?» 

Nov. 


24. ., . 
24. „ ( 


Altman, 


. 21.534 


fi 


25. „ 


Winckler, . 


. 21,857 
. 21,858 




30, „ ' 
30, ., ] 


Durr. . 


. 21,952 


Dec. 


1. „ ] 


Best, . 


. 24,065 


»> 


30. ., ( 



389 

Speciality, 
ion tubes. 
Petroleum motor, no 

valves (very simple). 
Fire engine propelled by 

portable petroleum 

motor. 
Qaa or oil engine (simple). 
Keservoir, for petroleum 

motor. 
Pneumatic motor. 
Gas or other motor, 

general design. 
Spray apparatus for hydro- 

carburetted air engine. 
Feeding oil engines. 
Keversmg gear for oil 

engines. 
Hydrocarbon motor, 

general design. 
Gas motor, vehicles. 



APPENDIX.— SECTION D. 

SUMMARY OF EXPERIMENTS ON A TWIN-CYLINDEU 
OTTO GAS ENGINE. 

By Dr. A. SLABY. 

Object. — ^Tbese valuable experiments were made by Dr. A. Slaby, Pro- 
fessor at the Technische Hocn-Schale, Berlin, to investigate the heat cycle 
in a gas engine. The object with which they were undertaken was, in Dr. 
Slaby's words, to " determine by measurements the division of heat in a 
gas engine, in order to deduce therefrom the conditions for the best utilisa- 
tion of the combustible." They have been published from 1890 to 1892 
in six pamphlets, comprising 196 pages, illustrated by man^ plates and 
diagrams, and form the most exhaustive treatise on this particular subject- 
with which the author is acquainted. An abstract of their contents is herd 
given, and will, it is hoped, serve as an introduction to that careful study 
of the original, which Dr. Slaby's laborious researches merit. 

The engine experimented on was a twin-cylinder horizontal 8 H.P. 
German Otto engine, employed for driving the electrical laboratoiy in the 
Berlin Technical High School. The gas used was always lighting gas. 



made from Upper Silesian coal, from the gas-works at Charlottenburg, 
near Berlin. The diameter of the cylinder was 172*5 mm. a 6 '8 inches, and 
stroke 340 mm. ~ 13 '3 inches. In all, 306 experiments were made, from 1886 
to 1890. divided into two sets, but Dr. Slaby is still continuing his work on 
the same engine. For further details of the motor see p. 391. 

Heating Value of the Gas.— Pamphlet I. — The author begins by ex- 
pressing his desire to elucidate the various questions still undecided in the 
theory and practice of the gas engine. With this object it is necessary, he 
considers, first to determine the composition and heating value of the gaa 
used. The chemical constituents of any gas depend upon the raw material 
(coal), the process of generation and purification, and time which has elapsed 
since the beginning of distillation. But the difficulty of arriving at an 
exact knowledge of the heating value and composition of any given gas ia 



390 APPBHDIZ. 

10 great as to be almoet insuperable. The sabject has never been thorooghly 
investigated. All that can oe done, to ensure uniformity in the conBtitaento 
of lighting gas during a test, is to cany out the experiments always at the 
same hour of the day, with gas firom the same main. 

Not only is the composition of gas given differently by different author- 
ities, but the proportions of heavy hydrocarbons are variously estimated. 
Some writers class them all as C4H8, some as CjfiU, some as half one, half the 
other, producing a difference in the heatins value of the gas of 8 per cent. 
ThiB method was not sufficiently accurate ror the author's purpose. After 
many trials he found that the heat value, of each hydrocarbon could be 
expressed as 

H = 1,000 + 10,500 X the density of the hydrocarbon 

(H representing the heating value in calories per cubic metre), and that 
this formula was also applicable to any siven mixture of the same. It was 
necessary, therefore, to determine the density of each gas to within ] per 
cent. , instead of taking the residuum in the gaseous mixture, after analysmg 
the different constituents H, CHi, CO, &c., as nitrogen, and reckoning ita 
weight as such. 

To calculate the density of the hydrocarbons, a Schilling apparatus was 
used, of which a drawing and detailed description are given in the originaL 
By this instrument it was found that the densities of any two gases were 
inversely proportioned to the squares of their speed of discharge, at the 
same pressure, through a narrow orifice. The experiment being carried 
out first with air, then with gas, the density of the latter was thus deter- 
mined. Great care was taken to ensure an even temperature. Satisfactory 
results were obtained by these means, but it was necessary to check them 
by experimenting upon perfectly dry lighting gas ; the Schilling apparatus 
being immersed in water, the gas in it was always slightly ^unp. The 
difference between moist and dry gas was considerable. Saturated air 
toeighed 0*75 per cent, ligfUer than dry air, but aaturcUed ga4 weighed 0*94 per 
cent, heavier than dry gas. The gas was next directly weighed. Two glass 
vessels were filled respectively with dry gas and dry air, and after beino; 
both brought to the same temperature and pressure, they were weighed. 
Immediately after, the glass vessels were weighed alone, and the propor- 
tional weights of the gas and air thus determmed. The correction for tiie 
Schilling apparatus was found to be only 0*07 per cent., but this accuracy 
was obtained after years of practice, comprising about 1,000 determinations. 
Finally the Lux gas weigher was used, and gave excellent results, about 
3*8 per cent, higher than the Schilling, owing to the dryness of the air 
and gas, and famts in calibrating. 

To determine the heat value of lighting gas, the percentage in volume 
of the heavy hydrocarbons was ascertained oy analysis. The specific weight 
of the gas being known, and the residuum taken as pure nitrogeoi, the 
specific weight of the heavy hydrocarbons was deduced firom the weight of 
the gas with and without them. This method has the disadvantage of 
assuming that the residuum consists entirely of pure nitrogen, whereas it is 
known to contain ammonia and other substances. A more satisfactory 
process was as follows : — ^The gas was first carefully weighed, then passed 
through tubes and vessels containing glass shavings, sulphuric acid, potash, 
water, &c., to separate the hydrocarbons and caroonic acid. The purified 
^as was then again weighed, and the density of the heavy hydrocarbons 
:ound by deduction to m a mean of 1 '72. This agreed well with the ordi- 
nary analysis of Berlin gas. It may therefore be assumed that in any given 
gas the mixture of heavy hydrocarbons is essentially a constant, the greatest 
difference in the heat value being 8 per cent. During one day of a triiJ, 
the difference was seldom more than 1 per cent. It is necessary, however, 
in making an experiment, to determine the heat value of the mixture of 



I 



DR. SLABT'S SXPSRIMENT8. 391 

heavy hydrocarbons, which vary from 13,000 to 27,000 calories per cubic 
metre. Throughout the experiments it was taken at 19,000 calories per 
cubic metre. 

Produota of Oombustion. — In the Second Pamphlet the composition of 
the products of combustion is considered, and the constants determined. 
The specific weight of 1 cubic metre is 0*417, with a heating value of 
4,883 calories. For complete combustion the weight of oxygen required 
for 1 cubic metre of lighting gas is 1*515 kilo., and of air 6*425 kilos, or 
4*965 cubic metres. The combustion produces 6*965 kilos, or 5 '684 cubic 
metres of products, or a contraction of 4*8 per cent. Analyses of the 
products of combustion with different dilutions of air were carried out oo 
seven different days, and the mean taken. In none of them could any trace 
of unburnt hydrocarbons or carbonic oxide be discovered. These analyses 
do not give the percentage of steam, which is certainly superheated, and is 
reckon^, for the above proportions, at 1 '209 cubic metre. The different 
constants for proportions of 5, 6, 7, and 8 volumes of air to one of gas are 
shown in a table and plotted out, namely — Percentage of contraction during 
combustion ; weight and specific weight of 1 cubic metre of the mixture 
before combustion, and of 1 cubic metre of products ; and constants of the 
products. 

The next question to determine was the specific heat of the products of 
combustion. The author distinguishes between true and mean specific 
heat ; the former increases twice as much for a given increase of tempera- 
ture as the latter. The increase in true specific heat per degree rise in 
temperature, for the gas composing the products of combustion in a gas 
engine, is given from Mallard and Le Chatelier, and the values calculated 
at constant pressure, and at temperatures of 0% 100°, 600°, 1,000°, 2,000° C. 
From these the specific heats, at constant pressure, of the products of com- 
bustion under the same conditions are reckoned, and plotted out. The 
horizontal lines show the rise in temperature of the gases from 0° to 2,000°, 
the verticals the increase in their specific heat at constant pressure, for a 
given dilution of gas and air. 

ZSngine and Instruments. — The exneriments to verify these calculations 
were carried out on the engine alreaay described (drawings of which are 
given). The quantities of gas, air, and of cooling water were carefully 
measured. During the experiment only one cylinder was used, the other 
being employed to determine the piston friction. The quantity of eas was 
measured by a glycerine gas meter, marked to show half litres, the con- 
sumption for the ignition flame being given by a separate meter. Both 
meters were carefully tested before the experiments, and thermometers 
inserted in them, from which the temperatures could be read off From 
the meters the ffas passed to the engine through rubber ba^ a pressure 
gauge being fixed in the admission passage. In all the experiments the air 
was measured in a gas meter, provided with a scale, thermometers, and 
pressure gauge. The error in this meter was found to be under i per cent. 
The air was forced into the air meter by means of a small fan, driven by a 
little water motor. The pressure was determined by passing it, before it 
entered the meter, through a small air holder, maintained by weights at a 
constant height. The cooling jacket water passed to the engine through 
pipes in which small copper tubes were inserted, one at the entrance, the 
otner at the exit; these tubes contained delicately graduated thermo- 
meters. The quantity of water was previously measured in gauged tanks, 
and afterwards passed into another tank. 

The governor was not acting during the experiments. The opening 
admitting the gas could be adjusted by means of a screw, but in the trial 
the mixture was kept uniform, with the same proportion of gas. Speed 
counters were arranged on the crank shaft and valves. 

Temperature of Gases at Exhaust.— The next question was to deter- 
mine the temperature of the gases of combustion* The author began by 



392 APPEKDIZ* 

takine the temperature with pvrometen 6xed in the exhaust passage, 
but lound an error of 60** in the best instruments. He next ojierated 
with ordinary glass, quicksilver, and nitrogen thermometers, marking up 
to 400" C. By cooling the cylinder very considerably, and greatly reducing 
the speed, it was possible to reduce the temperature of the exhaust gases to- 
the desired limit. No practical results were, however, obtained until a ball 
calorimeter was used. In the ordinary exhaust pipe a cock was fixed 
which, when open, allowed the gases to pass in the usual way into the 
atmosphere. When closed, the gases of combustion were forced through 
another channel, joining the main exhaust pipe at a point below the cock. 
In this pipe was a hollow cock, the socket of which contained an iron ball. 
By turning the cock 90"* either way the ball could be introduced into the 
socket, or allowed to fall out below. To make an experiment, the gasea 
were first shut off from their usual course, and the side cock opened, causine- 
them to flow through an auxiliary pipe. The ball being previously placed 
in the socket, and kept in position by wire-netting, it was exposed for 
half an hour to the current of the hot exhaust gases. A calorimeter con- 
taining water was then placed beneath it, the cock turned, and the ball 
dropped into the calorimeter, when its temperature was determined in the 
usual way by the rise in temperature of the water. The author thua 
succeeded in obtaining accurately the temperatures of the exhaust gases 
which, plotted on a curve, were compared with those arrived at with an 
ordinary thermometer. 

The indicators employed were of various kinds. No brake was used on 
the engine during the experiments, because the author, who worked for 
the most part entirely without help, was not able to carry out brake at the 
same time as calorimetric experiments. The brake efficiency was at other 
times carefully noted. 

Volume of Clearance Space. — The compression or clearance space of 
the engine was 60 per cent, of the total suction volume of the piston. This 
was determined — 1, By direct measurement of the internal dimensions of 
the cylinder; 2, by filling the cylinder with water, and thus measuring 
both the compression space and volume engendered by piston. 

Piston Friction. — The piston friction was next calculated, the heat 
thereby generated affecting materially the heat balance of the motor. This 
was done by shutting off one of the two cylinders, and running it without 
gas ; the vise in temperature of the jacket water gave the heat due to the 
piston friction. Seven experiments were made on two different days, and 
50 litres of circulating water used. The trial varied from half an hour 
to an hour and a half, and the rise in the temperature of the water, cor- 
rected for the heat of the room (which was always about 3** higher than 
that of the water at discharge), varied from 5° to 8". The number of calories 
carried off per cycle varied from 0'09 to 0*13. The mean temperature 
of the walls was about 3° below that of the water at discharge.* The 
results, when plotted out, showed that the friction of the piston decreased 
with the rise in temperature of the walls for about the same number of 
revolutions ; in other words, the higher the temperature of the walls, the less 
heat was carried off by the jacket water, or the less friction was generated. 
This was clearly revealed by the experiment of the 21st April, 1888, and the 
piston friction was found to depend not on the speed, but on the mean tem- 
perature of the walls. Thus with a mean wall temperature of 9* '4, the 
neat generated by the piston during two revolutions, or one cycle, was 0*183 
calorie, with a wall temperature of 16° '6 it was 0*17 calorie. The speeds 
varied from 97 to 182 revolutions \yeT minute. These results are worked 
out and summed up in a table, showing the generation of heat by piston 
friction, with a wall temperature of lO"* to 55**. Taking into account the 
indicated work, the author arrived at the conclusion that, the lower the 

* The temperature of the cast-iron cylinder tvall tvas always taken as a mean bstween 
the temperature of inlet and outlet of Jacket water. 



DR. slabt's experiments. 393 

toaU tempercUure the greater the friction. With a temperature of 10% 
nearly one-third the indicated work was expended in piston friction; ii 
sank to 6'5 per cent., with a wall temperature of 40°, corresponding to a 
temperature of the water at discharge oi 70**. If it were possible to reduce 
the wall temperature to 3°, the engine would not be able to overcome the 
frictional resistance. 

General Cycle. — Pamphlet in. — ^The amount of heat turned into indi- 
cated work during a complete cycle in a gas engine, is influenced by the 
following factors :-^l, Heat value of the eas ; 2, piston speed ; li, tempera- 
ture of the waUs ; 4, proportion in which the gas is diluted with air, or 
with neutral gases ; 5, amount of compression before ignition. To study a 
gas engine properly, each of these five should be separately varied, the 
others being mamtained constant. The heat value of the gas having been 
already considered, the next question is the influence of the piston speed. 
The author found that his experiments did not confirm the general opinion 
that the e£Bciency increased with the speed. The gas consumption per 
I.H.P. per hour, when the engine was running at 87 and at 180 revolutions 
per minute, was practically the same, the temperature of the out jacket 
water varied only T or 3°. The I. H. P. was more than one-third higher at 
the above high speed, but the negative work was greatly increased. ** As 
these results were questioned," says the author, ** I repeated my experi- 
ments in sets of two together on the same day, and proved that, if a motor 
is allowed to run continuously for some time, and the speed be increased, 
certain phenomena intimately connected with it make their appearance, 
which not only counterbalance the favourable effect of the augmented 
speed, but act prejudicially in the opposite direction. These influences are 
principally numifested by the rise m temperature of the products of com- 
bustion, and the increase of the negative work, corresponding to the periods 
of exhaust and admission in the gas engine. The Increase in negative work 
was revealed by the indicator which, with a weak spring, showed that the 
mean pressure corresponding to the negative work rose from 0*070 kilo, 
per square centimetre when the engine was running at 92 revolutions, to 
0*242 kilo, per square centimetre at 191 revolutions. The temperature at 
which the products were discharged rose at the same time more than 150°." 

Two series of experiments were undertaken to determine the influence of 
the speed, and yielded results at variance with those obtained by Professor 
Witz. The temperatures of the jacket water and exhaust gases were 
measured as described. 

The cycle of the gas engine was divided into—l. Admission; 2, Com- 
pression ; 3, Icnition ; 4, Expansion ; 5, Discharge, and each of these 
periods was studied experimentally. 

Considering first the admission period, the author found that thoagh the 
proportion of air to gas varied a little, the mean temperature of the jacket 
water, or that of the walls, rose slightly, though not m every case, and the 
temperature of the exhaust eases always, in almost exact proportion to the 
increase in the speed. With 90 revolutions the exhaust temperature was 
400" C, and with 170 revolutions, 529° C. The total volume of the charge 
drawn in per stroke decreased with increase of speed; with double the 
revolutions it fell more than 20 per cent. This proportion varied in the 
different experiments, the difference being less, the higher the speed. It 
was clearly a result of the available admission volume, which was dependent 
on the pressures at beginning and end of the cycle, and upon the mean 
temperatures at these two periods. To determine the pressure during 
admission, it was necessary to know how far the line of admission varied in 
pressure from that of the atmosphere. This initial pressure was found to 
increase in almost exact ratio to the increase of speed, from whence the 
author concluded that it depended entirely upon the number of revolutions. 

Other experiments on the back pressure of the exhaust gases showed 
that, at the moment the exhaust valve closed, the pressure line rose 



394 APPENDIX. 

slightly, in fairly exact proportion to the number of revolutions. It waH 
alvrays higher with increase of speed, varying from 8 mm. with 98 revolu- 
tions, to 14 mm. with 184 revolutions (scale— 29 mm. a 1 kilo, per sq. cm.) 
Plotting out the values obtained, the author found that, however the 
conditions of discharge were varied, the pressures always rose with the 
increase of speed, but much more gradually after the engine had been 
running for an hour, and a certain equilibrium in workins was obtained. 
Thus l£e exhaust as well as the initial pressure depended entirely on the 
speed. 

The temperatures at admission and discharge of the gases remained to be 
oonsidered. The first the author had no means of determining. The 
temperature of the products of combustion left in the cylinder is about the 
same as that determined with the calorimeter and ball, but at the moment 
the exhaust valve opens, the author verified a sudden momentary rise 
of 2° or 3°. Nevertheless he assumed that the mean temperature of the 
products in the cylinder, and of the exhaust gases, was the same. The 
temperature of the exhaust gases was higher in the one set of experiments 
than in the other, about 3 per cent, absolute temperature at 150 revolutions, 
although the speed and the volume of the charge were the same, and this 
was explained oy the difference in pressure, which was 14 per cent. By 
itself this difference should have produced a higher exhaust temperature ; 
but the mean temperature of the walls was on the other hand 6^ lower, thus 
showing their influence on the temperature of the exhaust. The tempera- 
ture of the charge in the cylinder at the end of admission was obtained by 
calculation. Plotted out on curves, the figures showed that this temperature 
also increased with the speed, but not much. With double the number of 
revolutions, the increase was only from 106'' G. to 128*" C. The two 
•experiments showed the same variation of temperature as before verified, 
about T at equal speeds (150 revolutions). Hence the mean temperature 
of the products left in the cylinder had but a slight influence upon the 
mean temperature of the freshly admitted charge. The author was able to 
determine with certainty that the temperature of the charge at admission 
was about lOO*" higher than that of the cooling water at discharge. 

He sums up these researches by stating that the differences in the volume 
of the charge can be explained only by these differences of pressures and 
temperatures, which he formulates thus — 

pressure at admission of charge «,. a /x.ia v t 

—- — £. — ^-, 5-5- = 31 - 0'049 X number of revs.» 

abs. temperature at admission of charge 

^_Ereg ure.texl>a«,t ^^^_ 0-0288 x number of wvotatfon.. 
abs. temperature at exhaust 

These were the values for the first set of experiments. They differed in the 
second experiments chiefly in respect to the exhaust temperature and 
pressure, which, unlike the admission pressure and temperature, defended 
on the mean wall tempertUure as well as the speed. 

Walls during Admission— Speed Effeot. — The author next endeavoured 
to determine the action of the walls during admission, their temperature 
being then lower than that of the gases in the cylinder. The difference 
between the heat given off by the products in the cylinder, and that ab- 
sorbed by the fresh charge passes into the cooling water, and it is necessaiy 
to know the weights of the products, of the gas, and of the air composing 
the charge. The weight of the products he found to diminish in exact ratio 
to the increase of speed, being with 90 revolutions 3*21 grammes, with 184 
revolutions 2*88 grammes. The specific heat of the products increases. On 
the other hand, the heat carried off to the cooling water during admission 
increases greatly with the speed. In the first set of experiments it rose 
from 0*08 caL to 0*16 cal., the speed being doubled, and in the second irom 



DR. blast's sxpe&iments. 395 

0*02 cal. to 0*10 cal. for the same increase of speed, tlie temperature of the 
walk in the latter case being about 5** higher. <'It follows," says Dr. 
Slaby, " that for the heat given off to the walls the rise in temperature of 
the products, increasing with the speed, has a far greater effect than the 
diminished time of contact with the walls." 

Hence he deduces that the pressures and temperatures at admission and 
exhaust are variable, and depend on the speed, and the mean temperature 
of the walls. The admission pressure and temperature depend on the 
speed, and are but slightly affected by the temperature of the products with 
which the fresh chMge mingles, and that of the cooling water. The 
exhaust temperature and pressure are greatly affected by the walls. If no 
water is allowed to collect in the exhaust pipe, the pressure of exhaust 
becomes a function of the speed, and the proportion of pressure to tempera- 
ture of exhaust, the wall temperature and dilution of the charge being 
maintained constant, can be approximately calculated from the speed. Thus 
formulie are obtained for calculating the volume of the charge admitted 
per stroke, the total weight (including that of the products) and quantity 
of heat given to the cooling jacket. The author considers that the greater 
the number of revolutions the smaller the charge, and he says further : — 
" If the quantity of gas admitted is smaller at high than at low speeds, it 
will be evident that the difference between the heat given off by the 
products during admission, and the heat taken up by the freshly admitted 
charge must bo considerably increased by increase of speed." 

Indicators. — Pamphlet TV.— The least known part of the gas engine 
cycle is that comprising the ignition and expansion of the charge. There 
is only one way of determining the connection between the spread of the 
flame and the cooling influence of the walls, namely, an analysis of the indi- 
cator diagram. The author, therefore, devotes the whole of this pamphlet 
to an exhaustive study of indicators (Crosby and others) and a determination 
of their limits of error. The indicators chiefly used during the experiments 
were a Crosby and a Storchschnabel. 

Compression. — Pamphlet Y. deals with compression in the gas engine. 
During this period the amount of heat set in motion and its direction should 
be determined. The problem is simple, if the compression curve be re- 
placed by a " poly tropic " * curve. 

pif» = const. 

The initial pressure having been shown to depend entirely on the speed, 
the compression pressures must be taken from tibe diagrams. The mean 
pressures for two sets of experiments are given in tables, and when plotted 
out, the abscissae representing the number of revolutions, and the ordinates the 
pressures of compression in millimetres above atmosphere, these compression 
pressures are shown to follow a strict law, and to decrease in proportion to 
the increase of the speed. This law the author reduces to a formula. From 
the two sets of experiments he lays down the proposition that the compression 
pressure depends entirely upon the speed of the engine, and can be reckoned by 
a given formula. Desiring next to know if the compression curve agreed 
with the polytropic during its whole course, he calculates the pressures, at 
half way through the stroke, from all the diagrams of the second set of 
experiments. They were also found to diminish with increase of speed, 
though not to the same extent as the initial pressures, and thus the com- 

Eression curve agreed with the polytropic throughout its course, and could 
e accurately circulated, the exponent being 1 *29. To prove its variation 
from the adiabatic, the author reckoned the speciflc heat for both curves at 

• "Polytroplo " is the name given by Zenoer to any carve which can be represented by the 
fofrmniap V* = constant The isothermal and adiabatic carves come nnder this law, with 
different exponents, m; the polytropic may be called the generic curve, of which the iso- 
thermal and adiabatic are varying forma. For a fall explanation of the law, see Zeuner, 
Thtrmodfnamik, and SohOCtkr. 



396 APPENDIX. 

constant pressure and Tolnme of the mixture of gas, air, and products. It 
was considerably higher for the adiabatic than for the' polytropic curve, 
with wliich he had proved the compression curve to agree, and hence he 
concludes that during compression there is a loss of hecU to the walls. Other 
conditions being equal, this compression pressure is a function of the speed. 
Thus at 100 revolutions, the initial pressure being atmospheric, the pressure 
of comjiression is 3 '50 kilos, per square centimetre; at 200 revolutions 
(double speed) it is 3*06 kilos. 

The mean temperature during compression increases with the speed. 
With a mean temperature of 200** C. the specific heat of the products of 
combustion is ITS per cent, higher than at 0**. The mean rise is 130**, the 
proportion between the initial and compression temperatures remaining 
constant at 1 '32. The work of compression, especially the increase in the 
iuternal work, also depends upon the speed. The change of condition is 
accompanied by a carrying off of the heat, but this abstraction of heat is 
small, and slightly diminishes with iDcrease of speed. 

Ignition Period.— The next question considered is the ignition period. 
This can only be studied by the help of the indicator diagrams taken by 
the author in each experiment. The differences in the diagrams obtained 
under precisely similar conditions the author attributes to the varying 
composition of the gas mixture which, even if the valve action is perfectly 
regular, is subject to uncontrollable fluctuations, due to slight differences 
in the speed of ignition. It is well known from Mallard and Le Chatelier*8 
ex|>eriment8 that the speed of ignition increases up to a maximum with 
increasing richness in the ^as mixture, but if the proportion of gas be still 
greater, it falls again. The indicator diagrams showing the effect of & 
richer or poorer mixture give curves sinking regularly one below the other 
with the decrease in the proportion of gas in the mixture, but do not explain 
the variation in the rounding shape of the top of the diagram. The author 
does not attribute this to the ignition flame, but considers that it is probably 
caused by differences in the local arrangement of the charge, and not by 
fluctuations in the strength of the mixture, which can hardly occur when 
the engine is running regularly. The small, perfectly vertical part of the 
indicator diagrams obtained by him is due to the force of the explosion in 
the ignition port ; the rest of the line, deviating more or less from the per- 
pendicular, represents the ignition of the remainder of the charge. At the 
top of all diagrams (taken with double springs) he found a distinct ** nick," 
marking the |K)int where expansion and fall of pressure began. To this, 
the point of highest temperature in the cycle, he devoted careful study. 

Considering first the temperature ana pressure of compression, and of 
this maximum point in the diagram, he reckons the mean specific heat of 
the charge at constant volume from that at these two points. The amount 
of heat shown by the diagrams in the area enclosed between the point of 
highest compression and of maximum temperature (ignition), the atmo- 
spneric line and the corresponding ordinate of pressure, is always less than 
that set free by the combustion of the gases. This difference in heat must 
be accounted for in one of tbree ways. Either it is developed during this 
period, in which case it must be entirely absorbed by the walls ; or incom- 
plete combustion, ** nachbrenneu " takes place; or both processes are 
combined. Analyses of the products prove that, at some period of the stroke, 
there is perfect combustion of the whole gaseous mixture. If the heat 
passes into the walls, the amount thus transferred must be in proportion 
to the surfaces in contact, time of exposure, and difference of temperature. 
If * * nachbrennen " is produced, it must depend on the proportional compo- 
sition of the charge, and on the speed, and be increased by poorer mixtures 
and greater speeds. The flgures obtained by the author show, especially 
with reference to the speed, that this is not so. Taking the difference 
between the total heat of the charge at this point of the stroke, and the 
heat of combustion shown in the diagrams, and plotting them out, the 



DR. slaby's experiments. 397 

author finds the percentage of this difference to be higher with low than 
with greater speeds, being 8*5 per cent, with 179 revolutions, and 13*2 per 
cent, with 100*6 revolutions. At 150 revolutions about 10 per cent, of the 
total heat disappeared. As neither the surfaces nor the maximum temper- 
atures vary much, the differences producing this loss of heat must lie in the 
time of wall contact. If all this heat passes into the walls, it will be pro- 
portioned to the time the indicator pencil takes to travel from the compres- 
sion to the ignition point, or what the author calls the *' time of ignition.*' 
The phenomenon cannot be caused by irregularities in the action of the 
engine, because these, when tested for time with the usual tuning-fork appa- 
ratus, were found to be less than i per cent. ; the speed was therefore 
constant. 

The authpr proceeds to find the angle through which the crank passes 
during this period, and expresses in a formula the proportion between the 
distance passed through, and the angle of crank revolution. By these 
means he was able to determine the time occupied in traversing the distance, 
in proportion to the speed, which, when plotted out, showed that the shorter 
the time the less heat disapjpeared. The increase in the heat lost was pro- 
portioned to the duration of combustion. Hence the author assumes that, 
at the point of highest tempercUure combuation is emled, and the heat not 
shown in the diagrams has whoUy passed into the walls. 

Speed of Ignition.— Having thus arrived at the time of ignition, the 
author was able to determine approximately the speed of ignition. By 
calculation and measuring the diagram, he reckoned tiie total length of the 
ignition channel in proportion to the length of stroke, and was thus able to 
express the ignition speed in a formula. This speed of ignition was nearly 
doubled with twice the number of revolutions, being for 100 revolutions 2*6 
metres per second, and for 180 revolutions 4*5 metres. These figures agree 
with Mallard and Le Chatelier, who found that the speed of ignition increased 
greatly when the gas was in a state of violent motion, and attributed the 
phenomenon not only to conduction, but to differences of speed in the 
component parts of the gas. As the charge in a gas engine must be in 
violent motion during ignition, combustion is really complete at the point 
of maximum temperature, between ignition and expansion. Thus there is 
a sudden explosion and rise in pressure at first, then a powerful flame darts 
into the cylinder, and with a smaller speed of propagation ignites the 
whole charge. This speed of propagation is affected by— Composition of 
the mixture ; speed of the engine (shown in the more rapid motion pro- 
duced in the cylinder) ; the ^urticular local stratification of the gaseous 
mass, whether homogeneous or otherwise. Combustion is completely ended 
in from 0*03 to 0*06 second, correspondinz to the maximum mean tempera- 
ture, after which expansion, without addition of heat, takes place. No 
dissociation is possible, since the maximum temperature is never above 
1,600° C. During combustion the flame certainly comes in contact with 
the walls, and transfers to them some of its heat. But this is only from 
8 to 13 per cent, of the total heat, and therefore, considering the difference 
between the heat conductivity of the metal and that of the products of 
combustion, we may conclude that this contact does not last long. The 
process of combustion chiefly takes place in the kernel of the charge, sur- 
rounded by neutral gases. The author therefore is of Otto's opinion, 
and considers that the composition of the centre of the charge not being 
homogeneous, a more favourable economic effect is produced. 

Ezpanslon Period. — Pamphlet VI. treats of the period of expansion. 
The author calculates the heat lost to the walls during this period irom the 
difference between the area of work in the diagram, and tne total heat of 
the gaseous mass. The expansion curve he divides into sections, and traces 
polytropic curves from one ordinate of pressure to the next. The expo- 
nent, already given, is governed by the speed. The values thus obtained 
are plotted out, and when compared with true adiabatic curves, the author 



398 APFSNDIX. 

found that daring expansion there is a eontinvou* carrying off of a large 
amount of heat to tfie walls, the temperature falling al fir$t, and then rising. 
This is explained bv the combined influence of the decreasing temperature 
and increasing wall sur&ce exposed. At the beginning of expansion, tiie 
quantity of heat carried off is determined by the temperature, at the end 
of expansion, by the cooling wall surface. It is only at a speed of 400 
revolutions per minute that the expansion curve approximates to the 
adiabatic. 

Considering next the fact, shown already to be probable, that during 
expansion no increase of heat is produced by internal heating, the heat 
parted with extemallv must be at the ex[iense of the internal energy of the 
gas. This can be calculated from the temperatures and the corresponding 
specific heats at constant volume. The difference between this internal 
energy and the external work done shows the amount of heat imparted to 
the walls. These three quantities can be expressed either as heat or as 
work. As work they may be measured on the indicator diagram as func- 
tions of the lengths of stroke, and represent the divisions of heat. The 
two quantities of internal and external heat are reckoned for any given 
portion of the stroke, converted into units of work, and divided by the 
volume passed through by the piston. Plotted out, they show that the 
abstraction of heat by the walls follows a regular course. At first the walls 
are relatively very cool, and the temperature of explosion very high. As 
the wall temperature rises, less heat is abstracted, and at the end of com- 
bustion a minimum is reached. The heat curve now rises, because the 
cooling surfaces are increased by the out stroke, but about the middle of 
the stroke another fall is produced by the increased piston speed. It acain 
rises at the end of the stroke, as the speed is reduced. These curves show 
only the amount of heat actually abstracted, and do not enable us to verify 
the progress of combustion, and whether part of the heat carried off is 
developed b^ ** nachbrennen.'' They reveal, however, that the heat parted 
with to the jacket during expansion, is inversely as the speed. The higher 
the speed, the less heat is carried off 

Szhanst Period. — This may be divided into two parts. Ihiring the 
first) occupying the last tenth of the forward stroke, a portion of the gases 
escape, carrying off part of the total energy of the charse, in the uiape 
of ** force vivcy" or *' energy of exhaust'' (as Zeuner caUs it). The re- 
mainder of the gases are duscharged at lower speed daring the return 
stroke. The author endeavours to determine the heat ^ue of this 
"energy of exhaust" from the heat balance of the engine. The beat 
nceivSi is the heat set free by the combustion of the lighting ^as. The 
heat ^Ing out is divided into — 1, Indicated work, both positive and 
negative, measured from the area of the diagrams, and reduced to calories. 
2f Heat passing into the walls and carried off into the coolins water» 
less the heat absorbed in piston friction. The latter heat value is calcu- 
lated, as before stated, from the rise in temperature of the jacket water 
and the quantity used, which was always 2U0 litres ; the time of passini^ 
this quantity through the jacket varied from fourteen to twenty minutes. 
3, The appreciable neat carried off in the products of combustion. The 
weight 01 the products is known, being the same as the weight of gas and 
air admitted per stroke. Their mean temperature is calculated from the 
weight of the eas and air, plus their specific heat at constant pressure^ and 
the difference between the temperatures at admission and exhaust. The 
values obtained are shown in a table. 4, Heat value of the work of resist- 
ance during exhaust. TMs Ib reckoned from the difference in volume^ 
namely, the increase dnrinc the time from the opening of the exhaust valve 
to the end of the stroke (i3)out one-tenth of stroke), and is distinet from 
the heat value of the return or exhaust stroke. 6, The "energy of 
exhaust," or the momentum of the products at the beginning of exhaust^ 
ahown by the difference between the presnue at the opening of the 



DR. blast's experiments. 399 

exhaust valve and the oonBtant back pressure during the return exhaust 
stroke. This difference is plotted on a curve. 

The variations shown are referred by the author to the accumulated 
action of the walls. Time is necessary, that the metal may reach a state 
of thermal equilibrium. At the beginning of an experiment the walls are 
still affected by the preceding trial, and contain more or less heat, accord*- 
ing to the previous speed of the engine. In this way the author deter- 
mmes the beat accumulated in the walls, that taken up by them, but not 
carried off in the cooling jacket, and that withdrawn from the walls, but 
not from the cycle. The values obtained for this "energy of exhaust'*' 
give the mean speed of the sases during the last tenth of the forward stroke, 
reckoned from their weight, as compared with the total weight of the 
products during exhaust. The speed depends on the mean speed of the 
engine. 

Lastly, the total heat discharged from the begiuning of exhaust to the 
admission of the fresh charge is reckoned, and the difference between it 
and the heat of the products remaining in the cylinder. It represents an 
energy transformed into—I. Energy of discharge; II. Back pressure 
negative work ; III. Work of exhaust ; and IV. Energy carried off in the 
water. The author concludes that, in the escaping gases and the producta 
remaining in the cylinder, there is a certain amount of energy or work 
represented by their temperature. The difference between this tempera- 
ture and that at the dosing of the exhaust valve represents a loss of energy 
carried off during exhaust mto the atmosphere, or to the walls. There is ai 
perceptible increase in this heat parted with to the walls, with increase of 
speed in the engine. 



400 



APPENDIX. 



APPENDIX— SECTION E— TABLE OF TRIALS— 



Lenoir (old 
type), 



Hagoni 
Brayton, 



Simon, 
Beck, 

Otto and 
Langen, 



Otto (Ger- 
man type), 



Otto-CroM- 
ley, 



Clerk, 

Atkinson 

(Differential 

Engine), 



Experiment 
iu»deb7 



Tresca 

Clerk 

Treflca 
Thurston 

Kennedy 

Tresca 

Clerk 

Brauer & 

SUby 
Brauer & 

Slaby 
Slaby 

Brauer & 
Schottler 
Meidinger 
Allard& 
Tresca 
Witz 
Garrett 

Brooks & 
Steward 
Adams 



Society 
of Arts 
Kidwell 
& Keller 
Capper 
Garrett 

Kobinson 



Schottler 
& Atkin- 
son 



Plftoe and Date. 



Paris, Jan., 1861 

„ March, 1861 
London, Dec., 1885 



Paris, Feb., 1866 
New York, 1873 

London, Febii 1888 

Paris, Sept., 1867 

Oldham, Aug., 1884 

Berlin, Mar., 1878 

Erfurt, Aug., 1878 

Deutz., Aug., 1881 

Altona, Sept, 1881 

Karlsruhe, 1882 
Paris, 1881 

Koubaix, 1883 
Glasgow 

Hoboken,XJ.S.,1884 

Crystal PaUce,1881 
»i »« 

London, Sept, 1888 

Pennsylvania 

London, 18d2 
GUsgow, 1885 

London 
Magdeburg, 1886 



Daratlmi of 
Tert. 



\ hours 



2i .. 

i .. 

n „ 

i „ 

1 .. 

24 



30 „ 

6 houn 
3 „ 
2 „ 

1 ■■,. 

i » 



Dlmeniluns of 
Engine. 



DUtnLof 
Cylinder. 



7Ar"»«- 
7in 



13 „ 



7-5 „ 

12-5 „ 
5in 

6A., 
6J„ 



8-5 „ 

13 „ 
12 ,. 

9-6 „ 



8;6„ 
9 " 



Nnmher 
permtn. 



Stroke. 



4 ins. 

it! :: 

121 „ 



1?:: 



40-5,, 
11 ., 
13i „ 
131 .. 

1»A» 

13 A,. 
16 „ 

H „ 

{2 :: 

18 „ 



18 
12 
20 



130 

94 

85 



63 



146 
206 

81 

28 explo- 
sions. 
180 revs. 

160 

157 

159 

159 
155 

]59| 
154 

158 

151-3 
158-7 
160 
160 

161-6 

162-6 
146 
132 
148 



159 



TABLE OF TRIALS. 



401 



GAS ENGINES USING LIGHTING GAS, 1861-1893. 







Cub. ft. of 


Cub. ft. of 






Aatborlty. 


IndlcKted 
H.P. 


^ffJ* 


per hour, 
deluding 
Ignition. 


Oas burnt 
perB.H.P. 
per hour, 
including 
ignition. 


Mechani- 
cal Bfl- 


British T.U. 
perLH.P. per 


Tho woid "dlitsnm" la thli 






dency. 


hour. 


oolamu ui4waa that An lodieator 
dlMgnm of the tnal li glwn in 
ilM text. 


... 


0-57 


112 


... 


... 


... 


A f Males du Comervor 
toiredesArUetAfHieri. 


I'-ir 


0-90 


96 
73-6 


... 


..« 


... 


Clerk! 'on the Bxplowm 
of Oascous Mixturu, 
p. 43. 














3-55 


2-07 


92 


... 


0-58 


... 


AnnaUa du Comerva" 
toire dei ArU et Afitiera. 


8e2 


3-98 


32-06 in- 
eluding 


... 


... 


... 


Clerk, The Gas Engine, 


5-60 


4-20 


^mp 




0-75 




Richard. 


8-05 


6-31 
0-46 


21 «8 


27-67 
48-7 


0-78 


121682 


Professor Kennedy's 
Report, Diagram. 

AnncUes du Conserva- 
toire. 


2-9 


20 


28-6 


42 


0-69 


19,999 


Clerk, Ocu Enginet 

Diagram. 
Witz, Moteurs d Oaz, 


3^ 


2-08 


40-2 


••■ 


0-65 


22,069 














p. 206. 


603 


3-98 


38 


... 


0-66 


... 


1* ft 


6-04 


4-4 


28-3 


32-4 


0-87 


12,094 calo- 
rics per kiL 


Jenkin, Oas and Caloric 
Engines, Diagram. 


4nom. 


3-96 


... 


32 


... 


... 


SchotUer, Die Oas 
Masc/Une, p. 87. 


6-24' 


4-11 


... 


a3 


... 


,, 


„ If p. 86. 


3-94 


... 


31 


0-74 


18,841 


Witz, Moteurs, p. 209 














(Twin cylinder engine). 


3-3 


3-7 


... 


39 


0-85 


... 


„ p. 210. 


14-26 


9-08 


19-4 


28-0 


0-63 


... 


Clerk, Gas Engines^ 


9-6 


8-1 


24-5 


291 


0*83 


L5,118 


p. 181, Diagram. 
„ „ p. 175, Diagram. 


33-6 


27-75 


26-04 


30-3 


0-82 


16,000 


1 1naugaral Address to 


22-56 


18-31 


23-6 


291 


0-81 


15,080 


- Society of Electri- 


3-42 


2-87 


30-9 


33-4 


0-84 


19,746 


l cian8,1884. 

Report of Trial, Diagram. 


1712 


14-74 


2076 


2410 


0-86 


12,120 


4-94 


a*. 


22 


... 


... 


... 


Witz, Moteurs, p. 217, 
Diagram. 


13-32 


11-33 


20-87 


25-22 


0-86 


... 


Page 355 of this work. 


905 


7-23 


24-30 


30-42 


0-80 


19,756 


\ Clerk, Oas Engines, 
) p. 191, Diagram. 
Robinson, Oas and 


27-46 


23-21 


20-39 


2412 


0-84 


16,577 


2nom. 


26 


... 


25-77 


... 


... 














Petroleum Engines, 
p. 45. 
Schottier, Die Oas 


... 


2-22 


... 


30-5 


••• 


... 














Maschine, p. 168, 














Diagram. 



26 



402 



APPBHDIX. 



TABLE OF TRIALS— GAS ENGINES 



Gu 



Szp6rliiM&t 



PlaetaadDfttew 



Dontionof 



Dbnemfoitt of 
Enclne. 



INinLof 

Qjrliiider. 



StrokA. 



Hmnbcv 
ofBevi. 



AtidnBoii 



Griffin, 



Bissohop, 

Fawcett, 

Acm^, 

Forward, 

Simplex, 

Lenoir (new 
typ«). 



Kiel, 



RaTel 

Chazon, 

Wittigand 
Hi 



Ueckfeldt 
(old type), 
Koertmg 
(new type), 



Bern, 
Adam, 

Ltttzky, 



Ilnwin 



Society 
of Arta 
Com- 
mittee on 
Science 
and Art 
Society 
of Arte 
Kennedy 
Jamieson 
Meidinger 

MUIer 

Jamieson 

Bowden 

Robert 
Smith 
Wita 

Tre«» 

Hinbh 

Moreau 



Monnier 
Wita 

Brauer & 
Schottler 
Sch&tUer 



Fischer 
E.MtiUer 



Bichard 
Prof. 

Aeppli 
SchrGter 
Sch5ttler 



London, Apr., 1887 

„ Sept, 1888 
Franklin Inst 

London, Sept, 1888 

Kihnamock, 1888 
„ Nov., 1887 

Liverpool,Feb. ,1890 

Glasgow, Mar.,1889 

„ Dec., 1890 

Birmingham, May, 

1888 
Rouen, Nov., 1886 

Paris, May, 1885 

„ May, 1890 

„ Jan«, 1891 



Soire-le-Chatean, 

Apr., 1889 
Altona, 1881 



Hanover, Dec., 1890 

Feb., 1889 

Carlsmhe, 1886 

Carlsruhe, 1886. 
Winterthur, 1889 

Munich, Jan.. 1886 
Harbnrg, 1891 



1 hour 



mins. 
hours 



nuns, 
hours 



.30 mins. 
22 „ 

40 „ 

ihour 



40 mins. 

1 hour 
43 



7*5ins. 
9-5 „ 

9-2,, 
9'' 

I" 

7-02,, 
71 „ 
51 „ 
9 „ 
7 „ 

7tV„ 

71 „ 
7A„ 



9'25in8. 
12«, 

H „ 

14 ,, 
14 



1610,, 
15* „ 
11 „ 
15f ,. 
14 „ 

14i „ 
14i„ 

7A». 
1H„ 



148 

131 

128 

198 

224 

183 

81 

151 
173« 

176-8 

161 

176 

160 

160 

161 

166 

103 
U9 

151 

204 

162*6 

167-8 
180-6 

173-8 
200 



TABLB OF TRIALS. 



403 



USING LIGHTING GAS^Cimtinwd. 







Cub. ft. of 


Cab. ft of 






Authority. 

Th« void "dlamm* la thii 
oolumn iDMUii that u Isdloator 
diagnm of th« trial !■ glTca In 


lodleatkL 
H.P. 


Br»k« 
H.P. 


per hour, 
IncIadiDg 
ignition. 


^la^ 
igniUon. 


Mechani- 
cal Effl- 
dencjr. 


perLH.P.'per 
hour. 


5-66 


4-89 


1978 


22-50 


0*88 


12,435 


ReportofTrialtDiagram. 


U15 


9-48 
10-03 


19-22 


22-61 
22-25 


0-85 


11,250 


19 99 

Report. 


16-47 


12-61 


23-10 


28-66 


0-80 


13,300 


KeportofTrial,Diagram. 


17-46 


14-94 


18-92 


23-58 


0-85 


12,089 


Report. 


17-28 


13-6 


19-27 


24-48 


078 


12^13 


Report of TrialfDiagnm. 
Schottler, Die Gaa 




0-45 


74 


... 


... 


... 


11-49 


8-62 


18-4« 


2474 


074 


13,082 


ifojcAinc p.30. 
MiUer, On Efflciencg. 


10-04 


8-84 


18-9 


21-5 


0-87 


15,365 


>f )» 


Onom. 


8-28 




17-3 


••• 


'^r 


Report of TriaL 


5-64 


4-8 


2079 


23-97 


0-86 


13,284 


Reportof Trial, Diagram. 


910 


8-79 


... 


20-38 


... 


^^'^.rp. 


Witz, Report 


2nom. 


1-93 


... 


23-19 


... 


14,887 „ 


Report of TriaI,Diagram. 


16 „ 


16-13 


... 


21-2 


... 


13,610 „ 


Report (Two-cylinder 

engine). 
Camptes Bendus, Soc. 


5-26 


471 




27-2 


0-79 


17.462 „ 














des Ing^nieurB Givila, 














Oct., 1891, Diagram. 


9-31 


701 


... 


377 


075 




Witz, Moteurs, p. 218. 


4nom. 


4-18 


... 


18-6 


••• 


13,446*,, 


11 »* 


4 „ 


3-75 


... 


43-5 


... 


... 


Schottler, DU Oa$ 
Machine, p. 146. 


3 „ 


2-18 


... 


45 


... 


... 


Witz, Moteurs, p. 208. 


16 „ 


2013 


... 


23-8 


... 


... 


Report of TriaL 




6-66 


... 


30-0 


... 


... 


Report (Twin-cylinder 
engine). 


4nom. 


6-61 


... 


^ 


... 


... 


Schottler, Die Gas 
Maechine, p. 169. 
Report of TriaL 


i " 


4-47 


... 


31 


... 


... 


2 „ 


2-46 




33 


... 


... 


»» n 


10 „ 


1116 




31-6 






«t t> 




6-29 




24 






Zeiiaehriftdes Verekiee 
Aug. 22, 189L 



* BxDludJng ignltioD. 



404 



APPENDIX. 
TABLE OP TRIALS OF GAS ENGINES 



Gai Engine. 



Experiment 
nude by 



Place and Date. 



Dimenkione of 
Engine. 



Dian. 
ofCjl. 



Stroke. 



Duration 

of 

Teat. 



No. of 

Revoln- 



Otto 

Otto (Germaii type), 



Croaaley-Otto, . 



Atkinson (Cycle 

Engine), 
Simplex, . . • 



D. K. Clark 



Teichmann 

and Booking 
Beck 

Monaco, Italy 

Crossley 

Spioer 

Severn Tweed 

Co. 
DowBon 

Tomlinson 

Witz 



1881 
Deutz, 1887 

Nuremberg, 

1888 
Canale, Jan., 

1890 
Dec, 1882 

Godalming 

Dec., 1891 

Mead.. Chel- 
sea, Feb., /92 

Uxbridge, 
Oct., 1891 

Nov., 1885 

Sept., 1890 



13^ 



13 in. 
several 

17 in. 

14 ,. 
71.. 

22-6.. 



18 in. 
eogines 

24 in. 

14f^in. 
15} in. 
38 in. 



ehrs. 
6 .. 
8 .. 



56hr8. 
8 .. 
6 ., 
2 „ 



156 
140-5 

140 



155-7 
86 
164 
100-8 









TABLE 


. OF OIL ENGINE 


OU Engine. 


Spec, 
prav. 
of Oil. 


Experiment 
madebjr 


Place and Date. 


Dimensioni of 
Engine. 


Duration 
Test. 


No. of 

ReTola- 

tiona. 


Diam. 
ofC/l. 


Strolce. 


Brayton, . . 
Piiestman. . . 


0-85 
0-79 


Dugald Clerk 
Unwin 


Glasgow, 
Feb., 1878 

Plymouth, 
1889 

HuU.1891 


8 in. 
8J„ 


12 in. 
12 ,. 


... 


201 
204 


»» • • 




» 


..• 


... 


SJhrs. 


2077 


f» • • 


0-81 


*i 


Plymouth, 

1890 
Plymouth, 

1891 

Guildford 


S^in. 


12 in. 


2i „ 


180 


>» • • 


... 


W.T. Douglass 


twin. 


cyl. en 


gine 


... 


Homsby- 
Akroyd, 
Trusty, . . . 


0-85 
0-81 


Robinson 
Beaumont 


8^ in. 
7*., 


14 in. 
14 „ 


3hr8. 
2 .. 


224 
230 


Otto, .... 


0-82 


Otto 


Dentz 


... 


... 


40min. 


212 


Lenoir, • . . 




Tresca 


Paris, 1885 


... 


... 


4ihn. 


159 


Durand, . . 


0-69 


... 


... 


... 


... 


2 ., 


180 


Forest, . . . 


... 


Martin 


Brest. 1890 


6 3 in. 


13-4 in. 


7 ,. 


1667 


LUde Langen- 
siepen. 


0-82 


Schottler 


Magdeburg, 


7-1 „ 


79„ 


1 » 


325 



TABLB OF TRIALS. 
USING DOWSON GAS, 1881-1892. 



405 



Indicated 
H.P. 


Brake 
11.P. 


4*41 


3-26 


... 


50-8 


••• 


30 


... 


35-95 


27-6 


... 


About 
400 total 
60nom. 


96-03 


1187 




21-9 


... 


810 


7-22 


110 


75-86 



Fael 
consumed 



iffi 



_ l.P. 

per hour. 

Anthracite. 



1-45 lbs. 



1-4 lb. 
1 » 

0-762 lb. 
1-06 „ 



Fuel 

consumed 

per 

per hour. 
Anthracite. 



1-97 Iba. 
1-7 „ 
1-97 „ 
1-9 ,• 



1-23 



1-33 „ 
1-34 ,, 



1^ 
SS 

II 



074 



Authority. 



The word *' dlAgram " In this ooliiinn mcMii that 
an Ittd.cator dUsnm of the trial U glTtn In tb« text. 



0-89 
0-69 



DowBon, CJieap Gas for Motive Power, 

Inst, C. K, vol. IxxiiL 
Schottler, Die Ocu Maschint, p. 102, 

Twin-'cyl. engine. 
Dowson, Oaa Power, 

Dowrson, Oas Power, Inst, Civil 

Engineers f vol. cxi. 
DowsoD, Cheap Oasfor Motive Power, 

Inst, C, B,, vol. Ixxiil 
Dowson, Gas Power j Inst. Civil 

Engineers^ voL cxi. 
Journal of Gas Lighting, Jan. 6, 

1892. 
The Engineer, Feb. 12, 1892, 

Diagram. 
The Engineer, Feb. 12, 1892, 

Diagram. 
Witz, Moteurs, p. 215. 

„ „ p. 220, Diagram. 



TRIALS, 1878-1891. 



ind^ated 


Brake 
U.P. 


6-39 net 


4-26 


9-36 


7-72 


7-40 


676 


6-24 


4-49 


25nom. 


26-6 


674 


... 


6-2 


4-28 


4noin. 


5-3 


4nom. 


4-16 


... 


2-88 


lOnom. 


16-67 


... 


67 



Consnmp- 

UonorOU 

per 

LH.P. 

per hour. 



2-16 lbs. 
0-69 lb. 
0-86 „ 
1-06 ., 



0-66 lb. 



Gonsnmp- 

UonofOll 

per 

B.H.P. 

per hour. 


Is? 

II 


Heating 
Value. 
T.U. 
perib. 


2-72 lbs. 


0-79 


11,000 


0-84 lb. 


0-82 


19,700 


0-94 „ 


0-91 


... 


1-24 „ 


0-85 


19,000 


0-88 pint 


... 


... 


o« ,• 


... 


•■• 


0-96 lb. 


0-68 


... 


0-886,, 


... 


... 


0-92,, 




... 


0-93,, 


... 


... 


1 „ 


... 


... 


0-83 „ 


... 


... 



Authority. 



Clerk, Gas Engines, p. 159. 

Institution CivU Engineers, 
vol cix., 1891. 



Engineering, Oct. 9, 1891. 

The Engineer, Dec. 4. 1891. 

Institution Civil Engineers, 

vol. cix., 1891. 
Witz, Moteurs, p. 215. 

p. 216. 

„ p. 219. 

Zeits, Ver, DeutscJier Ing,, 
Auk. 29. 1891. 



406 



APPENDIX* 



TABLE OF AIR 



AtrSiifln«. 


"sar' 


PlMWMidlMe. 


^^sgr^' 


DontloB 
Tot. 


Bmlo- 
tiooa. 


o?St 


StrakflL 


Buckett 

Baikj, 

Bonier 


Ingrey 
SUby 


Caloric Go. 
Cologne, 1887 


24111. 


16 in. 
6J .. 
13-8 „ 


2}hn. 


61 
106 
117-6 



GAS ENGINE 



Air Engine. 


Experiment 
nmdebr 


Place MdDftte. 


Engine. 


Dontloa 

of 

Test 


^ 


Dimm. 
ofCyL 


Stroke. 


""American Otto (twin 
cylinder). 


H. Sprangler. 


Schleicher, 
Schlum&Co., 
Philadelphia, 
May, 1893. 


14gin. 


25 in. 


3 days. 


160 



* Particulara received too late for inooipontion in body of work. 



TABLB OV TBIALS. 



407 



ENGINE TRIALS. 



In^nted 
H.P. 


?$f 


per boor. 


Gonsnnip- 
UoDOfFuel 

B.ffp. 
pwhoor. 


F- 

s* 


▲nthoiitj. 


20-2 
2-37 
5-86 


14-39 
1-31 
4-03 


1-8 Um. 
4« .. 
31 „ 


2-64 Ibi. 
3« „ 


071 
0-66 
0-69 


J«iikin, Cku and Caioric Engines, 
Inat. a E., 1883. 

ZeUa. Ver. Deuttchtr Ing., toL 
zxziiL, p. 89. 



USING PRODUCER GAS. 



ingjted 


i'^.^ 


Gonsamp- 
tlonofFuel 

iS.p. 

per hour. 


B-fii. 
per hour. 


^^ 


Aakhoritj. 


127-6 


92-5 


0-95 lb. 


1-31 lb. 


072 


Jcmmai of FranJ^in JiutUuU, May, 
1893. 



408 



BIBLIOGRAPHY. 



ChaUVeau, Gustave. Traits Th^oriqne et Pratique des Moteon k Gaz. 

Paris, Baudry k Cie., 1891. [The Author gives detailed Bibliography 

of French Works and Papers.] 
Clerk, Dugrald, The Gas Engine. Longmans, 1890. Third Edition. 
Clerk, DugalcL The Theory of the Gas Engine. Van Nostrand, New 

York, 1882. 

Boulvill, Professor. Th^orie des Machines Thermiqnes. Bernard, Paris, 
1893. 

Diesel, Rudolph. Theorie nnd Eonstmktion eines rationellen Wi&rme- 
motors. Berlin, Springer, 1893. 

Harris, H. Graham. "Heat Engines other than Steam." Cantor 
Lectures. May, 1889. 

Jenkln, Professor Fleemlng. Heat in its Mechanical Applications. 

**Gas and Caloric Engines.** Lecture delivered Feb. 21, 1884. 

Proceedings of the Institution of Civil Engineers. 
Knoke. Die Kraftmaschinen des Kleingewerbes. Berlin, Springer, 1887* 
Mallard et Le Chatelier. Recherches exp^rimentales et thtoriques sur 

la Combustion des melanges gazeux explosifs. Paris, Dunod, 1883. 
Mosll, A. Die Motoren fttr das Kleingewerbe. Brunswick, 1883. 
Ostwald. Verwandschaftslehre. Leipzig, Engelmann, 1887. 
Richard, Gustave. Les Moteurs k Gaz. Paris, Dunod, 1885. [With a 

large number of Illustrations.] 
Moteurs k Gaz et P^trole, 1892. 

Robinson, Professor William. Gas and Petroleum Engines. Spon., 
1890. " Uses of Petroleum in Prime Motors.** Journal of the Society 
of Arts. " Uses of Petroleum in Prime Motors.** Cantor Lectures. 
February, 1892. 

Schottler, R. Die Gas Maschine. Brunswick, Goeritz, 1890. [With 

detailed Bibliography of German Works and Papers.] 
Slaby, Dr. A. Calorimetrische Untersuchungen. Berlin, 1893. 

Vermand, Paul. Moteurs & Gaz et a P^trole. Paris, Gauthier Villars, 
1893. [With detailed Bibliography.] 

WltZ, Alm6. Trait§ Th^orique et Pratique des Moteurs k Gaz. 3^me 
Edition. Paris, E. Bernard et Cie., 1892. [With detailed Biblio- 
graphy of French Works and Papers.] 



BIBLIOOBAPHT. 409 



PERIODICALS AND PROCEEDINGS OF SOCIETIES AND 
INSTITUTIONS. 

Annales de Phynque et de Chimie. Paris. Various articles by Witz. 

„ du Conservatoire de» Arts et Mitiers, Paris. 
Ba/yeriBche Kunat-und Oewerheblatt. Munich. 
C(w$%er*» Magazine, New York. 
Compter Bendus de VA cademie des Sciences, Paris. 

,» de la SociSt^ des Inginieurs Civils, Paris. 

Dingler's Polytechnischer JoumcU, Stuttgart. 
Engineer, The, London. 
Engineering, London. 
Engineering Review, London. 
Journal fUr Gas Beleuchtung, Munich. 

,, of the Chemical Society, London. 

„ of Oas Lighting, London. 

,, of the FranUin Institute, Philadelphia. 
Liverpool Engineering Society (Miller). Liverpool. 
Moteurs d Qaz et d Pitrole (Wehrlin). Paris Exhibition, 1889. 
Philosophical Magazine, London, 18S4. Vol. ii. (Ayrton and Perry). 
Proceedings of the Institution of Civil Engineers. London. 

„ ,, ,, Mechanical Engineers, London. 

Bevue Oin^ale des Sciences, Paris. 

,, Technique de V Exposition Universelle, Paris, 1889. 
SoaiU d^ Encouragement de VIndustrie Naiionale, Paris. 

„ Technique de VIndustrie de Gaz, Paris. 

„ Industrielle du Nord, Lille. 
Society of Arts (Gas Engine Trials, dsc) London. 
Zeitschrift des Vereines deutscher Ing4niewre, Berlin. 

iiTo^e.— See also List of Proceedings, Periodicals, and Reports, in Trials 
of Gas, Oil, and Air Engines, Pages 400-407. 



411 



IISTDEX. 



Abkl's test to determine flmhmg 

point of oil, 267. 
AbeciaMB and ordinatee, definition 

of, 218. 
Absolute temperature, 208. 

„ zero, 208, 210. 
Acm^ gas engine, 126. 
Actual heat efiScienoy, definition of, 

235. 
Adam gas engine, 171. 
,, petroleum engine, 329. 
,9 single-acting and twin-cylinder 
types, 171, 174. 
Adams, Professor, trial of Otto 

ensine, 03. 
Adiabatic curve, 215. 
Admission of gas and air to a 

cylinder, 7. 
Advantages of gas en^es, 2. 

„ of oil engmes, 283. 

Ailsa Crag lighthouse, oil gas en- 
gines on the, 281. 
Air engmes, Bailey, 347. 
„ B^er, 352. 

„ Cayley-Buckett, 339. 

„ Ericsson, 345. 

„ Rider, 349. 

„ Robinson, 344. 

,, Stirling, 341. 

„ theory of, 337. 

„ Wenham, 346. 

Air governor. Simplex ensine, 144. 
Albwt petroleum motor, 324. 
Altmann and Ktippermann, 330. 
American oil, 264. 

„ oil engines, 331-334. 
»f ^7P^ ^^ Prieetman oil en- 
gine, 305. 
Application, period of, 28. 
ArboB, cheap gas inrstem, 195. 
Argentine Eepublic, petroleum on 
rulways of, 277. 



Atkinson cycle gas engine, 100. 

„ differential g^ engine, 98. 

„ engine, SoSety of Arts' 
trial, 108. 

„ engines, principle of, 96. 
Atmosnheric gas engine, Barsanti 

and Matteucci, 25. 
Atomic weighs, 222. 
Atoms and molecules, 221. 
Avogadro's law, 221. 

B 

Bailet engine, trial of a, 348. 
Bailey -Friedrich, oil and steam en* 

gine, 277. 
Bailey hot air engine, 347. 
Baku oU fields, 264. 
Balance of heat, 234. 
Baldwin gas engine, 73. 
Barber, 18. 
Harnett's engines, 21. 
Barsanti and Matteucci's atmospheric 

gas enfldne, 25. 
Beau de Kochas — 

Abstract of patent, 366. 

Cycle in gas engines, 41. 
„ oil engines, 308. 
Beaumont, trial of Trusty oil ensine 

314. 
Beck, six-cycle gas engine, 61. 
Beechey, Fawcett gas engine based 

on patents of, 123. 
B^ier and Lamart gas engine, 70. 
B^ier hot air engine, 352. 
Benz, gas engine, 175. 

„ „ electric ignition, 177. 

Berliner Maschinen-Bau Gesellschaft 

gas engine, 184. 

„ „ oil engine, 330. 

Berthelot and Vieille*s experiments, 

velocity of flame propagation, 246. 
Berthelot and Mahler s fuel oidori- 

meters, 225. 



412 



INDEX. 



Bischof gas prodncer, 193. 
Bisschop atmospheric gas engine, 50, 

Boyle's law, 206. 
Brayton carburator, 290. 
„ gas enjpne, 51. 

. „ oil engine, 289. 
Brest, trial of the Forest engine at, 

325. 
British thermal nnits, explanation 

of. 211. 
Brooks and Steward— Otto diagram, 

236. 
Brown, 20. 

Brunler, oil engine patented by, 331. 
Bunsen's experiments -- Velocity of 

flame propagation, 243. 



Calculation of efiiciency. Otto 

engine, 241. 
Calories, ex]ilanation of term, 211. 
Caloritic value of one cubic foot of 

coal gas, 226, 230. 
Calorimeters, fuel, Berthelot and 

Mahler's, 225. 
Calorimetric experiments. Dr. Slaby, 

on a gas engine, 389. 
Campbell gas engine, 137. 
Capitaine engine, theory, 185. 
,, gas engine, 185. 
,, oil engine, 326. 
Capper, Professor, trial of an Otto 

engine, 355. 
Carburators, Brayton, 290. 
,, Lenoir, 318. 

„ Lothammer, 285. 

„ Meyer, 286. 

„ Schrab, 286. 

„ Simplex, 320. 

Carburetted air, 191, 284. 
Camot's formula, 216. 
„ law, 213, 215. 
„ theoretical cycle, 13. 
Cayley-Buckett air engine, 339. 

,, engine, trials, 340. 

Charles' law, 207. 
Charon gas engine, 155. 
Chauveau, principle of flame propa- 
gation, 164. 
Cheap coal in Lencauchez generator, 

199. 
Chemical composition of gas, 221. 
,, equations, 224. 
,, symbols, 222. 
Classification of gas engines, 15. 
„ oil engmes, 308. 



Clerk, Dngald, experiments on ex- 
plosion of gases, 249. 
Clerk gas engine, 57. 
9t » governor, 60. 
„ „ slide valve and ignition, 

58, 59. 
,, theory of dissociation, 257. 
„ trials on a Brayton oil engine, 

292. 
,, ,, Clerk gas engine, 60. 

,, ,, Hugon gas eogine, 39. 

„ ,, Otto and Langen gas 

engine, 49. 
Clntch gear, Otto and Langen, 46. 
Coal gas, composition of, 226, 229. 
„ distillation of, 191. 
,, table of products of com- 
bustion, 228. 
Coefficient of expansion in gases, 208. 
Combustion, changes produced in 
gases by, 243. 
,, of gases, oxygen required, 227. 
Comparison of eas with steam power, 
232. 
,, of theoretical and actual 

diagrams, 236. 
Composition of oil, 265. 

,, poor gases, 231. 

Compressing type of gas engine, 15. 
Compression, advantages o^ 10. 
,, first suggested by Lebon, 20. 
,, in a gas engine, 10. 
,, the chief improvement in the 
Otto engine. 74. 
Conditions of ideal efficiency, 217. 
Consumption of gas — 
In Acme engine, 127. 
In original Lenoir engine, 30. 
In Otto engine, 90. 
Cooling action of walls, Witz's deter- 
mination of, 249. 
Cost of working with petroleum fuel 

in Russia, 275. 
Cycle, Beau de Rochas', 41. 
„ Camot's perfect, 214. 
„ engine, Atkinson's, 100. 
,, Ericsson's, 218. 
Cycle of operations in a gas en^e, 7. 
„ table of, in BeoL engme, 62. 
Cycle, Stirling's, 218. 
„ term first used for gas engines 
by Sadi Camot, 13, 
Cylinder wall action in gas engihes^ 
259. 



DATMT.EB gas engine, 178. 

„ petroleum engine, 328. 



INDEX. 



413 



Davy, ezperiments on ice in a vacnum, 

210. 
Day, gas engine, 135. 
Dead points, outer and inner in a 

crank motor, 16. 
Definition of terms relating to com- 
bustion, 243. 
Degrand, suggestions of, 24. 
Dclamare-Deboutteville and Malan- 
din, makers of the Simplex engine, 
138. 
Densities of oil, varying, 266. 
Deutzer Gas-Mo toren Fabrik, 

founded, 50. 
Diederich's engine, 1G2. 

, , makers of the Security oil 
engine, 321. 
Diesel engine, 354. 
Different applications of Lanchester 

self-starter, 95. 
Differential engine, Atkinson, 98. 
, , pistons, Siemens regener- 

ative engine, 295. 
„ piston, Trent engine, 132. 

Different methods of evaporating 
petroleum, 308. 
„ sizes and types of Otto 
engine, 87* 
Discovery of law of mechanical equi- 
valent by Him, Joule, 
and Mayer, 209. 
,, of petroleum in America, 

265. 
,, „ in Kussia, 264. 

Distillation of gas from coal, 191. 
,, oil gas, 278. 

,, petroleum, experi- 

ments on, 2C6. 
Dougill gas engine, 131. 
Douglass, W. T., trials on a Priest- 
man engine, 304. 
Dowson gas, 193, 200. 

„ for electric lighting, 121. 

,, producer, 200. 

„ trials with, 204. 

Drake gas engine, 24. 
Dresdener gas-motor, 182. 
Droojba oil fountain in the Caspian 

district, 265. 
Durand gas engine, 72. 
,, oil engine, 325. 
Dtlrkopp gas engine, 181. 



E 



Earliest attempts to obtain lighting 

gas, 189. 
Early combustion engines, 17. 



Economic motor (gas), 70. 

Effect of time on cylinder wall action, 

260. 
Efficiency formulae — 
Atmospheric gas engines, 240. 
Compression engine, explosion at 

constant pressure, 240. 
Compression engine, explosion at 

constant volume, 239. 
Direct acting non • compression 
engine, 239. 
Efficiency, four kinds of, 235. 
„ of air engines, 338. 

Electrical governor, Beck engine, 63. 
Electric ignition in the modern Lenoir 
en^ne, 154. 
„ „ Priestman 

engine, 301. 
,, „ Simplex engine, 

139. 
Equilibrium of heat, 254. 
Ericsson, 345. 

„ air engine, 346. 
,, cycle, 218, 345. 
Etincelle gas engine, 73. 
Evaporation of petroleum, experi- 
ments on, 270. 
„ n spirit, 306. 

Evaporative power of petroleum fuel, 

274. 
Ewins and Newman gas engine, 71. 
Exhaust, discharge of the gases, 9. 
Expansion, coefficient of, 208. 

„ in a gas engine, 9, 235. 
,, methods to obtain, 65. 
Experiments on petroleum, Robin- 
son, 269. 
Explosion and combustion in a gas 
engine, 9, 243. 
„ of gases, Clerk's experi- 
ments on, 250. 
Explosive force in gases, utilisation 

of, 5. 
Express gas engine, 131. 
Extraction of gas from coal, 190. 

„ i>etro]eum from shale, 

265. 



F 

FAWCETTgas en^ne, 123. 
Fielding gas engine, 128. 
First application of gas to lighting 

purposes, 19. 
First single-acting engine. Otto and 

Langen, 44. 
Fischer, Professor, trials of a Koert- 

iug engine, 171. 



414 



IKDEZ. 



FUshing point of petroleum, 287* 
Fog aignaU, Priestman engine nsed 

for.m 
Forest gu engine, modem type, 159. 
„ „ original type, 71. 

,, oil engine, 325. 
Forward gas engine, 129. 
Fonlis gas engine, 55. 
Four conditions of efficiency—^Beau 

de Rochas, 40. 
Four English engines heat balance 

sheet, &c., 242. 
Franfois gas engine, 71. 



Galltce, Forest and, makers of the 

Forest engine, 325. 
Gas, chemical composition of, 221. 
,, for motive IK) wer, 189. 
„ produced from combnstion of 
coal, 192. 
Gas engine — 
Cycle of operations, 7. 
Cylinders, wall action, 252. 
Gas engines — 

Advantages over steam, 2. 
Classification of, 16. 
Compression in, 10. 
For electric lighting, 120. 
Principles governing their con- 

strnction, 1. 
Starting, 3. 
Types, 14. 
Gascons f ael, 190. 
Gases — 
Laws of, 205. 

Specific heat at constant pressure, 
212, 223. 
„ „ ,» volume, 212, 

223. 
Gas producers, Bischof, 193. 
Dowson, 200. 
Kirkham, 193. 
Lencauchez, 197. 
Lowe, 196. 
Pascal, 194. 
Siemens, 194. 
Strong, 195. 
Tessi^duMotay. 194. 
Thomas and Laurent, 
193 

„ Wilson*, 197. 

Gay Lussac's law, 207. 
GiUes gas engine, 49. 
Governing of gas endues, 12. 
„ ,, oil engines, 317. 
Graphic representation of Camot's 
law, 215. 



Great Eastern Railway, petrolenm 

fuel on the, 276. 
Griffin oil engine, 316. 

„ six-cycle gas engine, 108. 
Grobe and L&rmann, gas for steel 

fomaces, 197. 



H 

Hallbwell gas engine, 60. 
Hambruch, improvements in Simon 

engine, 53. 
Hautefeuille, 18. 

Heat, mechanical equivalent of, 209. 
,, movements of,inacylinder,220. 
„ of combustion of gas, 205, 224. 
„ utilisation in a gas engine, 231, 
233. 
Heat balance sheet, &c, four English 
engines, 242. 
„ efficiency, 14. 
,, engines, source of power, 5. 
Heating value and composition of oil 
gas, table of, 279. 
, , of different oils, 269. 
„ of Dowson gas, 202. 
„ of Lencauchez gas, 199. 
„ of Siemens' producer gas, 
231. 
High speeds, advantages and disad- 
vantages of, 186. 
Him*s iMdance of beat in engines, 234. 
Hirsch, trials of a modern Lenoir 

engine, 155. 
Hock oil engine, 288. 
Hornsby-Aluroyd oil engine, 310. 
Hot air engines, efficiency of, 338. 
Hugon gas engine, 36. 
Huyghens, 18. 



Ideal efficiency, conditions of, 217. 
Ignition at constant pressure. Bray ton 
engine, 51. 
„ by £me in slide valve, Qerk 

engine, 59. 
„ by Hame propagation, Adam 

engine, 17SL 
„ „ „ Koerting engine, 164, 

167. 
,, „ „ Sombart engine, 184w 
„ cock, Bamett's, 22. 
„ hot tube, Stockport engine, 110. 
„ Otto engine, 81, 86. 
,, point of petroleum, 268. 
„ tube first employed by Fanok» 
74. 



IKDIX. 



415 



Imperfect ezpaiiAon in gMenffiiieSj96. 

Indicator diagrame, methodo! taking, 
219. 

Intennediate oils for making oil gas, 
278. 

Isherwood, experiments on petro- 
leum in manne boilers, 277. 

Isothennal cnrve, 214, 



Jamieson, Professor, trials of a Griffin 

enffine, 113. 
J e n K 1 n, Professor, regeneratiye 

engine, 351. 
JohnstoDo's condensing ozyhydrogen 

engine, 23. 
Joule's law of the mechanical equi- 
valent, 209. 
„ method of determining the 
mechanical equivalent, 211. 



K 

Eapfbl gas engine, 183. 
Keith oil gas producer, 281. 
Kennedy, Professor, on utilisation of 
energy, 261. 

„ trials of Beck engine, 63. 

,, „ Griffin engine, 1 12, 1 13. 

Kinder and Kinsey's engine, 39. 
Kirkham gas producer, 193. 
Koerting gas engine, 165. 

„ horizontal type, 168, 



tTpe of 1888, 165. 
[feldt gas engine. 



Koerting • Lieck: 
original type, 164. 



Lalbtk gas encine, 161. 

Lanchester self-starter, 94. 

Latent heat of evaporation of petro- 
leum, 271. 

Laviomery gas engine, 73. 

Laws of gases, 205. 
„ of thermodynamics, 209. 

Lebon, 20. 

Lencauchez gas, 193. 

„ producer, 197. 

„ ¥rith Simplex engines, 

Lenoir carburator, 319. 

„ gas engine, original type, 29. 
„ „ modem type, 151. 

„ petroleum motor, 318. 



Liquid fuel, 273. 
Lothammer carburator, 285. 
Lowe gas producer, 196. 
Lubrication in a gas engine, 11. 
Lude- Vulcan oil engine, 330. 
Lutzky-Nuremberg gas engine, 183. 



Mallard and Le Chatelier— 
Experiments on flame propagation,. 

244. 
Theory of increase of specific heat, 
259. 

Mansfield oil sas producer, 279. 

Marinoni, miOLer of the Lenoir en- 
gines, 29. 

Marietta's Law, 206. 

Martini gas engine, 67. 

Maximum theoretical efficien^, 236. 

Mead's fiour mills, trial with Uowson 
gas at, 205. 

Mechanical efficiency, 235. 

,, equivalent of heat, 209. 

Meidinger, experiments on Otto and 
Langen engine, 48. 
,, trials of a Bisschop en- 
f(ine, 116i 

Method of taking indicator diagrams^ 
219. 

Meyer carburator, 286. 

Midland gas engine, 130. 

Miller, T. L., experiments on a. 
Fawcett engine, 126. 

Million, 40. 

Mire gas engine, 73. 

Molecular weight, 223. 

Moreliu,^ Trials of aNiel engine, 161. 

Movements of heat in a gas engine 
cylinder, 220, 260. 

Murdoch, first to apply gas to b'ght- 
ing purposes, 19, 191. 



N 

National gas engine, 133. 

Natural gas, 191. 

Naumann, A., heat of combustion of 

gases, 205. 
Niel gas engine, 159. 
NitnM»n, (mution in atmospheric air, 

230. 
Nobel Brothers, oil industry developed 

by, 335. 
Noel gas engine, 72. 
Non-compressing type of gas engine, 

15. 



416 



iin>Bz. 



Oil eDgines, roquMites of, 297* 
„ gaa, 191,277. 
„ ,, producers, Keith, 281. 
„ „ „ Manstield, 279. 

„ „ „ Pintach, 282. 

„ „ „ Rogers, 281. 

„ „ „ Thwaite, 282. 

„ industry ia the Caspian region, 

334. 
„ motors, advantages of, 283. 
„ refuse used iu railways as fuel, 

276, 277. 
„ vaporisation of, 288. 
Oscillating engine, Kave], 54. 
Ostwald, heat of combustion of gases, 

225. 
Otto and Langen, atmospheric engine, 
43. 
„ ,, clutch gear, 46. 

„ domestic motor, 89. 
Otto eas engine-^ 

At Faris Exhibition, 1878, 61. 
Calculation of efficiency, 241. 
Description of, 76, 77, 78. 
Driven with Dowson gas, 87. 
„ oil gas, 281. ' 

Expansion in different cylinders, 87. 
Exhaust, 83. 
Governing, 83. 
Ignition, 81, 86. 
Lubrication, 84. 
Society of Arts' trials, 93. 
Stratification, 85, 255. 
Teichniann and Booking's trials 
with Dowson gas, 92. 
Otto indicator diagram, 236. 
,, oil engine, 315, 316. 
„ ,, trial of, 316. 

Oxygen required for complete com- 
bustion oi gases, 227. 



Palatine gas engine, 134. 
Papin, 18. 

Parts of an engine, 6. 
Pascal gas producer, 194. 
Patents, list of English, 368. 
Pendulum governor. Otto en^ne, 84. 
„ Simplex engme, 147. 
Perfect cycle, Carnot's, 215. 

,, diagram of, with com- 

Jression, 236. 
J 273. 
,, cost of, 274. 



Petroleum, derivation of the word,263» 
„ discovery of, 263. 
„ distillation of, 266. 
„ evaporative power of, 274. 
„ flasning point of, 267. 
„ fuel on tne Great Eastern 

Railway, 276. 
„ i» on the Russian South 

Eastern Railway,275. 
„ heating value of, 269. 
,, ignition point of, 268. 
Pieplu carburator, 286, 325. 
Pintsch oil gas system, 282. 
Poor ^ases, composition of, 231. 
Premier gas engine, 133. 
Pressures and volumes of a gas, 219. 
„ of oil vapour at varying 
temperatures, 271. 
Priestman oil engine,- American type, 
305. 
)f *i applications of, 302. 

»> 91 governor,' 301. 

,, ,, spray maker. 299. 

„ „ vaporiser, 300. 

Producer gas, 192. 

Products of combustion of gases, table 
of, 228. 



R 

Rack and clutch gear, Barsanti and 

Matteucci, 27. 
Ragot oil engine, 323. 
Ratio between theoretical and actual 
efficiency, 235. 
„ of specific heats, table, 213. 
Ravel gas engine, new horizontal 
type, 157. 
„ „ trial of a, 159. 

,, oscillating engine, 54. 
,, rotatory eneine, 54^ 
Reading Iron Works Co., makers of 

Lenoir engine in England, 30. 
Regenerative engine, Jenkin and 
Jameson, 351. 
„ ,, Siemens, 294. 

Regenerator introduced by Robert 

Stirling, 341. 
Regulation of speed. Otto enffine, 83. 
Reithmann, engine designed by, 35. 
Requisites of oil engines. 297. 
Retarded development of heat — 
Due to cooling action of the walls, 
258. 
,, dissociation, 257. 
„ increase of specific heat,259. 
,, strati tication, 255. 
Retorts, oil gas distilled in, 278. . 



tNDBX. 



417 



Bicliard, on wall action in gasenffines, 

252. 
Rider hot air engine, 349. 
Robey gas engine, 134. 
Robinson hot air engine, 344. 
Robinson, Professor, experiments on 
petroleum, 269, 270. 
„ on evaporative value of 

petroleum, 274. 
„ trial of aHomsbyengine, 
312. 
Rocket oil engine, 318. 
Rogers, Messrs., oil gas made by, 

279, 281. 
Root's gas engine, 137. 

,, petroleum motor, 314. 
Rotatory engine. Ravel, 54. 
Rowden, Professor, trials of Acm4 

engine, 127. 
Ruhmkor£f coil, Benz engine, 177. 

,, Lenoir engine, 34, 154. 
,, Simplex engine, 139^ 
Russian oil, 264. 

Russian South - Eastern Railway, 
petroleum fuel on the, 275. 



ScAVENOEB charge of air in gas 

engines, 62. 
Schmidt, Gustave, opinions of, 39. 
SchOttler, Professor- 
Experiments on stratification, 256. 
On boilers in gas engines, 52. 
On movements of heat, 220. 
Trial of Atkinson engine, 108. 
,, Koerting engine, 171. 
,, Ltide oil engine, 331. 
„ Lutzky engme, 184. 
„ Wittig k Hees engine, 65. 
Schrab carburator, 286. 
Schroter, Professor, trial of an Adam 

engine, 175. 
Scotch oil, 265. 
St^curit^ oil engine, 321. 
Self-starter, Lanchester, 94. 
Seraine gas engine, 66. 
Severn Tweed Mills, trial with 

Dawson eas, 204. 
Shipley, Rooson's gas engine, 133. 
Siemens, 39, 294. 

„ gas, 192, 231. 
,, „ producer, 194. 
„ regenerative engine, 294. 
Simon gas engine, 51. 
Simplex gas ensine, 138. 

„ „ driven with Lencau- 

chezgas, 199. 



Simplex gas engine, electric ignition, 
139. 
„ „ 100 H.P. dimensions 

of the, 149. 
„ „ starting gear, 148. 

Simplex oil engine, 320. 
Sin^e and double acting engines, 

difference between, 56. 
Six-cycle type of engine, 16, 61. 
Slaby, Dr., calorimetric experiments 
on an Otto engine, 92,389. 
„ trial of a B6nier engine, 
353. 
Slade, trial of a Lenoir engine, 35. 
Smith, Professor, trial of a Forward 

engine, 129. 
Society of Arte* trial— 
Atkinson engine, 108. 
Griffin „ 113. 

Otto „ 93. 

Sombart gas engine, 184. 
Source of power in heat engines, 5. 
Specific heat — 
Definition of, 211. 
Of gases at constant pressure, 212, 
223. 
„ „ volume, 212, 223. 

Speed in gas engines, regulation of 
the, 12. 
„ of expansion, Witz's experi- 
ments on, 218. 
Spiel oil engine, 292. 
Spontaneous ignition — 
In the Capitaine oil engine, 327. 
, , Homsby- Akroyd oil engine, 

310. 
,, Spiel oil engine, 294. 
Spray maker, Priestman engine, 299. 
Starting a gas engine, 3. 

„ apparatus. Clerk engine, 

„ gear, Simplex engine, 148. 
,, Otto engine, 85. 
Steam boiler of Simon gas engine, 

Stirling, Robert, 340. 
Stirling's first engine, 341. 

„ perfect cycle, 218, 341. 
„ second engine, 343. 
Stockport gas engine, 117. 

„ hot tube ignition, 
119. 
Stratification, experiments on, 255. 
,, in Lenoir engine, 33. 

„ in Otto engine, 85, 

255. 
Street, 19. 

Strong gas producer, 195. 
Sturgeon gas engine, 66. 

27 



418 



Index. 



Table of gas, oil, and air engine 
trials, 400. 
,, heat of oombustion of 

gases, 225. 
Tangye gas engine, 68, 121. 
Tanffye's works, Dowson gas at, 205. 
Tavlor introduoed first oil gas pro- 
ducer, 279. 
Teichmann, Professor, experiments 

on stratification, 256. 
Temperatures in a gas engine, 233. 
Tentmg gas en^e, 157. 
„ oil engine, 324. 
Tessi6 du Motay, gas producer, 194. 
Theoretical curves, amabatic, 215. 
„ „ isothermal, 214. 

„ formula, Gamot's, 216. 

Theory of air eneines, 337. 
Thermal units, definition of, 211. 
Thomas and Laurent gas producer, 

193. 
Thurston, experiments on Brayton 
gas engine, 53. 
„ experiments on Otto en- 

gine, 92. 
Thwaite oil gas producer, 282. 
Timing valves, 128. 
Tomlinson, trial of Atkinson engine, 

108. 
Tr^bouillet, cheap gas system, 195. 
Trent gas engine, 132. 
Tresoa— 
Experiments on Hugon engine, 38. 
„ Otto and Langen 

engine, 48. 
Trials of a Lenoir petroleum engine, 
319. 
,, modem Lenoir engine, 

155. 
„ original Lenoir engine, 
35. 
Trials— Me Table, 400. 

„ with Dowson gas, 204. 
Trusty gas engine, 133. 
,, oil engme, 312. 
, , -Connelly oil engine, American 
type, 333. 



Unwin, Professor, on evaporative 
value of petroleum, 
274. 
,, )> on utilisation of oil, 

286. 



Unwin, Professor, trial of Atkinson 
engine, 107. 
„ ,, ,, Priestman 

engine, 303. 
Urquhart on evaporative power of 
petroleum, 276. 
, , value of petroleum fuel, 

275. 
Utilisation of heat, 4, 232. 

„ oil, methods, 272. 

„ the explosive force in 

gases, 6. 
Utility type of Atkinson engine, 108. 
Uxbridge, Trial of Atkinson engine 
with Dowson gas at, 108. 



VAP0RI8ATI01I of oil, 288. 
Vaporiser, Priestman engine, 300. 
Variations in expansion curve, 254. 
Various small British engines, 135. 
„ French „ 162. 

Velocity of flame propagation — 
Berthelot and Vieille's experiments, 

246. 
Bunsen's experiments, 243. 
Mallard and Le Chatelier's experi- 
ments, 244. 
Victoria gas engine, 69. 



W 

Wall action in gas engine cylinders, 

252. 
Wall action in gas engine cylinders, 

Richard on, 252. 
Warchalowski gas engine, 72. 
Waste of heat, 3. 
Water gas, 192. 
Weatherhogg oil engine, 318. 
Wenham hot air engine, 346. 
Wilson gas producer, 197. 
Wittig & Hees gas engine, 64. 

„ ,, method of ignition, 

65. 
Witz, Professor, experiments on cool- 
ing action of 
walls, 258. 
„ lighting gas, 
247. 
„ trials of the Charon 

engine, 156. 
,, „ Simplex en- 

gine, 150. 
W ight, 21. 



INDEX. 419 



Yarbow, Measra., Zephyr spirit Zephyb spirit launch, descriptioD of 
launch, 305. | the, 307. 

,, tests on evaporation I Zeuoer, Professor, measurement of 
of spirit, 306. | heat, 220. 



THE END. 



i>ItIllTKJ) Br BKLL AND BAIN, LIMITSD, 0LA800W. 



A TREATISE ON. 

The Oeo^aphieal Distribation, Geological Oecurrenee, 

Chemistry, Production, and Refining of Petroleum; 

its Testing, Transport, and Storage, and the 

Legislative Enactments relating thereto ; 

together with a description of 

the Shale Oil Industry, 

BY 

BOVERTON REDWOOD, F.R.S.E., F.I.O., Assoc. Inst. C.E., 

Hon. Corr. Mem. of the Imperial Russian Teohnhal Society; Mem. of 

the American Chemical Society; Consulting Adoiser to the 

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the author is in an excaptioaaily favourable poaition to give; and (S) Boles for the Tbstiho, 
Tkakbpokt, and Htoragk or Petroleum— toese Bnbjeots are fally dealt with from the 
point of view of Lkoislatiok and the Phbcautions which experienoe in this and other 
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By A. E. SEAT ON, M.Inst. CE., M. Inst. Mech. E., 
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SOIEimflG AND TBOairOLOQICAL WOMXS. j. 

THE DESIGN OF STRUCTURES: 

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solved both analytically and graphically, as a guide to the Student. 

4. The chapters devoted to the practical side of the subject, the Strength of 
Joints, Punchmg, Drilling, Rivetting, and other processes connected with the 
manufacture of Bridges, Roofs, and Structural work generally, are the result 
of MANY years' EXPERIENCE in the bridge-yard ; and the information given 
on this branch of the subject will be found of great value to the practical 
bridge-builder. 



"Students of Engineering will find this Text-Book invaluable."— j^fcAiVcr/. 

'*'The author has certainly succeeded in producing a thoroughly pkacticaz. Text- 

"We GUI unhesitatingly recommend this work not only to the Student, as the bibt 
Tbxt-Booic on the subject, but also to the professional engineer as an BXCBBDiMOMr 
valuablx book of reference."— il/irciawtfa/ World. 

"This work can be confidbntly recommended to CQgineers. The author has wisclf 
diosen to use as litde of the higher mathematics as possible, and has thus made his book m 
■■AL 0«K TO TBK rju^CTicAL BUGiNBBK. . . • AncT caicfiil pcHiaalt we hflwe DotUng bot 
fnoM liar tbe woik."--Aklairr. 



LONDON: EXETER STREET, STRAND. 



4 CHABLBS OBIfFIK Js CO.'B PUBLICATIONS. 

ASSAYING <A Text-Book of) 

For the um of StudenU, Mine Managen, Attayen, dc. 



C. BERINGER, F.I.C., F.C.S., 

Late Chief Aasayer to the Rio Tinto Copper Company, Loodoa, 



J. J. BERINGER, F.I.C, F.C.S., 

Public haalytk for, and Lecturer to the Mining Astodation of, CorawalL 

With numerous Tables and Illustrations. Crown 8vo. Cloth, 10/& 
Second Edition; Revised. 



General Contents. 

Part I.— Introductory : Manipuuition : Sampling ; Drying ; Calculation of Re- 
flolt*— Laboratory-books and Reporu. Mbthods : Dry Gtavimetnc ; Wet Gravimetric- 
Volumetric Assays: Titrometric, Colorimetiic, Gasometric — Weighing and Measuring- 
Reagents— Formulae, Equations, &c.— Specific Gravity. 

Part II. — Mbtals : Detection and Assay of Silver, Gold, Platinum, Mercury, Copper, 
Lead, Thallium, Bismuth, Antimony, Iron, Nickel, Cobalt, Zinc, Cadmium, Tin, Tungsten^ 
Titanium, Manganese, Chromium, &c— £arths, Alkalies. 

Part III.— Non-Mbtals : Oxygen and Oxides; The Halogens Sulphur and Sul> 
phates — Arsenic, Phosphorus, Nitrogen — Silicon, Carbon, Boron. 

if/^MM/ur.^Various Tables useful to the Analyst 



"A REALLY MBRiTORious WORK, that may be safely depended upon either for 
instruction or for reference." — Nahtrt. 

** Of the fitness of the authors for the task they have undertaken, there can be no qoi^ 
tion. . . . Their book admirably fulfils its purpose. . . . The resulu given of 
an exhaustive series of experiments made by the authors, showing the effects of varying 
CONDITIONS on the accuracy of the method employed, are of the ittmost impobtancb." — 
Imd$utriMt. 

**A very g^ood feattue of the book is that the authors give reliable infonnation, mostly 
based on practical experience.''— J^M/fM/tfTMi/-. 

** This work u one of the bbst of iu kind. . . . Essentially of a practical charactor. 
. . . Contains all the information that the Assayer will find necessary ia the < 
of ainenls. ''—Engmter, 

LONDON: EXETER STREET, STRAND- 



SOIENTIFIG AND TECHNOLOGICAL WORKS. $ 

PHOTOGRAPHY: 

ITS HISTORY. PROCESSES, APPARATUS, AND MATERIALS. 

COMPRISING 

WOBKIRG DETAILS OF ALL THE MORE IIPORTAHT METHODS. 
By a. brothers, F.R.A.S. 

WITIf TWENTY-FOUR FULL PAGE PLATES BY MANY OF THE PRO- 
CESSES DESCRIBED, AND ILLUSTRATIONS IN THE TEXT. 

In 8vo, Handsonu Cloth. Price i8x. 



GENERAL CONTENTS. 

Part. I. Introductory— Historical Sketch; Chemistry and Optics 
of Photography ; Artificial Light (Electric and Oxyhydrogen Light, 
Compressed Gas, Ethoxo-Limelight, Magnesium Light, &c.) 

Part IL Photographic Processes, New and Old, with special 
reference to their relative Practical Usefulness. 

Part IIL Apparatus employed in Photography. 

Part IV. Materials employed in Photography. 

Part V. Applications of Photography ; Practical Hints. 



" Mr. Brothers has had an experience in Photography so large and varied that any work 
by him cannot fail to be interesting and valuable. ... A most coMPKKHaNSivs volume, 
entering with full details into the various processes, and vkry fully illustrated. Hie 
PRACTICAL HINTS are of GRBAT VALUiL. . . . Admirably got ys^**— Brit. Jour, o/ Photography. 

" For the Illustrations alone, the book is most interesting ; but, aport from these, the 
volume is valuable, brightly and pleasantly written, and most admirably arranged."— 
Photographic Newt, , 

" Certainly the pinbst illustrated handbook to Photography which has ever been 
published. We have three Photogravures, four Collotypes, one Chromo- Collotype, numerous 
Blocks, Photo-Quromo-Typograpn, Chromo-Lithograph, Woodbury-Type, and Woodbury- 
Gravure Prints, besides many others. ... A work which should be on the reference 
shelves of every Photographic Society." — Amateur Photographer. 

"This really important handbook of Photography ... the result of wide 
experience ... a manual of the best class. ... As an album of examples of 
phot(:>gxaphic reproduction alone, the book is not dear at the price. ... A handbook so 
tar in advance of most others, that the Photographer must not fail to obtain a copy as a 
reference 'myrkJ^—'PhotograpUc Work. 

*'The complstbst handbook of the art which has yet been published. There is no 
process or form of apparatus which is not described and explained. The beautiful plates 
given as examples of the different processes are a special feature."— .fc^/rMum. 

" Processes are described which cannot be found elsewhere, at all events in so convenient 
and complete a form." — English Mechanic. 

** The chapter on practical Hnrrs will prove invaluablb. Mr. Brothers is certainly 
to be congratulated on the thoroughness of his work."— i7ac(r Chronicle. 

LONDON : EXETER STREET, STRAND. 



OEARLBs aRtrnur s oo.'s publioationb. 



MINE-SURVEYING (A Text-Book of): 

For the use of Managers of Mines and Collieries^ Students 
at the Royal School of Mines, do. 

Bv BENNETT H. BROUGH, F.G.S., 

Late Instructor of Mine-Surveying, Royal School of Mines. 

With Diagrams. Fourth Edition. Crown 8vo. Cloth, 7s. 6d. 

General Contents. 

General Explanations — Measurement of Distances — Miner's Dial — ^Variation of 
the Magnetic-Needle — Surveying with the Magnetic-Needle in presence of Iron — 
Surveying \rith the Fixed Needle — German Dial — Theodolite — Traversing Under- 
ground-^urface-Surveys with Theodolite — Plotting the Survey— Calculation of 
Areas — Levelling— Connection of Undergroimd- and Surface-Survcys--Measuring 
Distances by Telescope — Setting-out — Mine-Surveying Problems — Mine Plans — 
Applications of Magnetic-Needle in Mining — Appendices, 

" It is the kind of hook which has long been wanted, and no English-speaking Mine Agent 
or Mining Student will consider his technical library complete without it.' — Nature. 

" Supplies a long-fblt want."— /f»«. 

" A valuable accessory to Surveydts in every department of commercial enterprise.**— 
Celiufy Cuarduut, 



^wo:ris: s 



By WALTER R. BROWNE, M.A., M. Inst. C.E., 

Late Fellow of Trinity College, Cambridge. 



THE STUDENT'S MECHANICS: 

An Introduction to the Study of Force and Motion. 

With Diagrams. Crown 8vo. Cloth, 4s. 6d. 

' dear fai style and practical in method, 'Thb Studbnt^s Mbchamics' is oonUaUy to be 

L from all points of view."— ^/EAamwiw. 



FOUNDATIONS OF MECHANICS. 

Papen reprinted 6nom the Engineer. In Crown 8vo, is. 



FUEL AND WATER: 

A Manual for Users of Steam and Water. 
Br Pbof. SCHWACKHOFER and W. R. BROWNE, 1£.A. (See p. 28). 



LONDON: EXETER STREET, STRAND. 



mjaurTtwfv Asn rmmxoLo&iOAL works. 
PRACTICAL GEOLOGY 

(^IDS IN): 

IVITH A SECTIOtf Otr PALEONTOLOGY. 



GRENVILLE A. J. COLE, F.G.S., 

Pro£MSor of Geology in the Royal College of Science for Ireland. 

Second Edition, Revised. With Numerous lUustrations. Large Crown 8va 
Cloth, los. 6d. 



OXKXBAZi CONTHNTa 
PART I.— Sampling of the Earth's Ckust. 
in the field. | Collection and packing of s; 

PART II.-^EXAMINATION OF MINERALS. 



Some physical characters of minerals. 
Simple testa with wee reagents. 
Elxajnination of minerals with the hlowpip^. 
Simple and characteristic reactions. 



Blowpipe-tests. 

Quantitative flame reactions of the feI^Ma9 

and their allies. 
Examination of the optical properties of 



PART III.— Examination of Rocks. 



Introductory. 

Rock-structures easily distinguished. 
Some physical characters of rocks. 
Chemical examination of rocks. 
Isolation of the constituents of rocks. 
The petrological microscope and microscopic 
preparations. 



The more prominent characters to be ob- 
served m minerals in rock-sections. 

Characters uf the chief rock -forming mineral* 
in the rock-mass and in thin sectioni. 

Sedimentary rocks. 

Igneous rocks. 

Metamorphic rocks. 



PART IV.— Examination of Fossils. 



Introductor]^. 

Fossil generic types.— Rhizopoda ; Spongiae ; 

Hydrozoa; Actinona. 
Polyzoa; Brachiopoda. 



Ptetopoda; 



Scaphopoda ; Gastropoda ; 

Cephalopoda. 
Echinodennata ; Vermes. 
Arthropoda. 
Suggested list of characteristic invertefarafer 

fossils. 



" Prof. Cole treats of the examination of minerals and rocks in a way that has ncfver 
been attempted before . . . obsbrving op the highk.st praise. Here indeed are 
' Aids' IKNUMBRABLB and INVALUABLE. All the directions are given with the utmost deai^ 
ness and precision. Prof. Cole is not only an accomplished Petrologist, he is evidently also 
a thoroughly sympathetic teacher, and seems to know intuitively what are stumbling-UockB 
to l^tmers— a rare and priceless quality."— >4/«l<>»«rMM. 

"To the younger workers in Geology, Prof. Cole's book will be as indispbnbabuc as » 
'dictionary to the learners of a language."— ^aAmii^ Revirtv. 

"That the work deserves its title, that it is full of 'Aids/ and in the highetft degree 
'fbactical,' will be the verdict of all who use it" — Nature. 

" A MOST valuable and welcome book ... the subject is treated on lines wholly- 
different from those in any other Manual, and is therefore very original."— <5'£r«i!(r# Gasti^* 

** A more useful work for the practical geologist has not appeared in handy form.' — 
ScvUisk Gtograpidcal Magazine, 

** This BXCBLLBNT MANUAL . . . Will be A VERY GREAT HBLP. , • • • The SOCtioo 

on the Examination of Fossils is probably the best of its kind yet published. . . . Full. 
of well-digested information from the newest sources and from personal resrarch ■ "— ^ nmaU 
9fNat, History, 



LONDON: EXETER STREET, STRAND. 



8 OBAJtLBS OBirriN S OO.'S PUBLI0ATJ0N8. 

SEWAGE DISPOSAL WORKS: 

A Guide to the Construetion of Works for the Prevention of the 
Pollution by Sewage of Rivers and Estuaries. 

BT 

W. SANTO CRIMP, M.INST.C.E., F.G.S., 

Late AinsUnt-Engiiieer, London County CoundL 

With Tables, Illustrations in the Text, and 37 Lithographic Platet. Mediam 
8vo. Handsome Cloth. (Second Edition in preparation.) 



PART I.— Introductory. 

Introduction. 

Details of River Pollutions and Recommenda- 
tions of Various Commissions. 
Houriy and Daily Flow of Sewage. 



The Pail System as Affecting Sewage^ 

■ 'om the Sewage 



Settling Tanks. 

Chemical Processes. 

The Disposal of Sewage^udge. 

The Pr^axation of Land for Sewage Di*> 

posaL 
Tahle of Sewage Fann Management. 



The Separation of Rain-water from 
Proper. 

PART II.— Sewage Disposal Works in Operation— Their 

Construction, Maintenance, and Cost. 

lUnstrated by Plates showing the General Plan and Arrangement adopted 

in each District 



Map of the London Sewage System. 

Crossness Outfall. 

Barking Outfall. ^ 

Doncaster Irrigation Farm. 

Beddington Irrigation Farm, Borough of 

Croydon. 
Bedford Sewage Farm IrrigiJion. 
Dewsbury and Hitchin Iiftermittent FH- 

tration. 
Merton^ Croydon Rural Sanitary Authority. 
Swanwick, Derbyshire. 
The Ealing Sewage Works. 
Chiswick. 

Kingston-on-Thames, A B. C Process. 
Salfoxd Sewage Works. 
Bradford, Precipitation. 

" All persons interested in Sanitary Science owe a debt of gratitude to Mr. Crimp. . • . 
His work will be especially useful to Sanitary Authoritiss and their advisers . . . 

■MINBNTLY PRACTICAL AND USEFUL . . . giveS plaUS and descriptions of MANY OP THE 

MOST IMPORTANT SRWAGK WORKS of England . . . With very valuable information as to 
Che COST of construction and working of each. . . . The carefully-prepared drawings per- 
Bit of an easy comparison between the different systems.**— jL«fff#A 

" Probably the most complbtb and bbst trbatisk on the subject which has appeared 
in our language. . . . Will prove of the greatest use to all who have the problem of 
Sewage Disposal to face. . . . The general construction, drawings, and type are all 



New Maiden, Chemical Treatment and 

Small Filters. 
Friem Bamet. 

Acton, Ferosone and Polarite Process. 
Ilford, Chadwell, and Dagenham Sewage 
DispMal Works. 
Coventry. 
Wimbledon. 
Birmingham. 
Margate. ». 

Portsmouth. 
Berlin Sewage Farms. 
Sewage Precipitation Works, Dortmund 

(Germany). 
Treatment of Sewage by Electrolysis. 



CRIMP (W. Santo) and COOPER (Ch. Hamlet): 

A POCKET-BOOK OF RULES, DATA, AND GENERAL 
INFORMATION, useful to Municipal Engineers, Surveyors, and 
Sanitary Inspectors. 

LONDON: EXETER STREET, STRAND. 



BCISNTiria AND TSaaNOLOaWAL WORKS. 9 

CROMPTON (R. E., V.P.InstE.E., M.InstC.E.): 

DYNAMOS (A Practical Treatise on). With numerous Illustrations. 
In Large 8vo. 

TVORKS 

By J. R. AINSWORTH DAVIS, B.A. 
PKonssoK or bioloqt, umvBKsmr coixxgb, ABBsrsTwrrB. 



DAVIS (Prof. Ainsworth): BIOLOGY (An Ele- 

mentary Text- Book oQ. In large Crown 8vo, Cloth. Second Edition. 

Part I. Vegetable Mosphologt and Physiology. With Complete Index- 
Glossary and 128 Illustrations. Price 8s. 6d. 

Part II. Animal Morphology and Physiology. With Complete Index- 
Glossary and 108 Illustrations. Price los. 6d. 

EACH PART SOLD SEPARATELV, 

*^* Note — The Second Edition has been thoroughly Revised and Enlarged, 
and includes all the leading selected Types in the various Organic Groups. 

''Certainly tmb but 'biology' ynrh which we are acquainted. It owes itt pr»- 
eminence to the fact that it is an bxcbllknt attempt to present Biology to the Student as a 
coitKBi.ATKD AND coMPLBTB sciBNCB. The glossarial Index is a most usbpul addition."— 
British Mtaical Journal, 

'* Furnishes a clbar and compkbhbnsivb exposition of the subject in a systkmatic 

**— Saturdajr Review. 

' Literally packbd with information."— <7£Mri;<mf Medical Journal. 



DAVIS (Prof. Ainsworth): THE FLOWERING 

PLANT, as Illustrating the First Principles of Botany. Large Crown 
8vo, with numerous Illustrations. 3s. 6d. Second Edition. 

" It would be hard to find a Text-book which would better guide the student to an accurate 
knowledge of modem discoveries in Botany. . . . The scibntific accukact of sutement, 
and the concise exposition of fixst principlbs make it valuable for educational purposes. In 
the chapter on the Physiology of Flowers, an admirable ritumi is given* drawn firom Darwin, 
Hermann MUllefj Kemer, and Lubbock, of what is known of the Fertilization of Flowers." — 
Journal o/the Linnean Society. 

DAVIS and SELENKA: A ZOOLOGICAL 

POCKET-BOOK; Or, Synopsis of Animal Classification. Comprising 
Definitions of the Phyla, Classes, and Orders, with Explanatory Remarks 
and Tables. By Dr. Emil Sclenka, Professor in the University of 
Erlangen. Authorised English translation from the Third German 
Edition. In Small Post 8yo, Interleaved for the use of Students. Limp 
Covers, 4s. 

"Dr. Selenka's Manual will be found useful hy all Students of Zoology. It is a compiib- 
■BNsrvB and successful attempt to present us with a scheme of the nattual arrangement of 
the animal world.** — Edin. Med. Journal 

"Will prove very serviceable to those who are attending Biology Lectures. . . • The 
tnmslation is accurate and dear."— Zaiv^ ^/. 

LONDON: EXETER STREET, STRAND. 



IP QSrJMLm QRIFFIN 4 0Q.'£ FUBLIOATIOHUL 

GAS, OIL, AND AIR ENGINES 

CA Practleal Text -Book on Internal Combustion Motors 
without Boiler). 

By BRYAN DONKIN, M.Inst.C.E. 
With numerous lUustrations. Large 8vq^ 2 is. 



Gbnkral Cohtbmts.— Gas fingtalM :~Genenl Deflcription— History and Develop- 
ment — Brituhf French, and German Gas Engines— Gas Production for Motive Power — 
Theory of the Gas Engine— Chemical Composition of Gas in Gas Engines— Utilisation of 
Heat— Explosion and Combustion. Oil Motors :—Histonr and Development— Various 
TVpes-^Pnestman's and other Oil Engines. Hot-AiF Enfflnes :— History And Develop- 
■ment— Various Types: Stirling's, Ericsson's, &c, &c 

"The BBST Booic NOW 7>UBUSHBD on Gtts, Oil, and Air Engines. . . . Mr. Donkin's 
book will be of vsrv gkkat intbkbst to the numerous practical engineers who have to 
nuke themselves familiar with the motor of the day. ... He has the advantage of long 
PSAcncAL BXPBKiBNCB, Combined with high scibntipic and expbrihbmtal knowlbdgb, 
and an accurate perception of the requirements of Engineers."— T'Ar Enginetr. 

"The intelligence that Mr. Bryan Donkin has published a Text-book should be good 
mbws to all who desire reliable, up-to-date information. . . . His book is most timely, 
and we welcomed it at first sight as being just the kind of book for which evervbody inter- . 
ested in the subject has been looking. . . . We hsartily kvcommbnd Mr. Donkin's 
work. ... A monument of careful labour. . . . Luminous and comprehensive. . . . 
Nothiqg of any importance seems to have been tatiiXUe^**— Journal of Gat Ligktmg. 



INORGANIC CHEMISTRY (A Short Manual erf). 

By a. DUPRie, Ph.D., F. R. S., and WILSON HAKE, 

Ph.D., F.I.C.« F.CS., of the Westminster Hospital Medical School 
Second Edition, Revised. Crown Svo. Cloth, 7s. 6d. 

"A well-written, dear and accurate Elementary Manual of Inorganic Chemistry. . . • 
We agree heartily in the system adopted by Drs. Duprtf and Hake. Will uakk \ 

MBNTAL Work TRBBLY INTBXBSTING BSCAVSB INTBLUGIBLB.**->S'a/Mn£^ Rovuw. 

"There is no question that, given the niRPBCT CRonrDiNC of the Student in his ! 
the remainder comes afterwards to him in a manner much more simple and easily acquired. 
The work is an bxamplb op thb aovantagbs op thb Systematic Trbatmbnt of a 
Science over the fragmentary style so generally fiollowed. By a long way thb bbst of tha 
•audi Maanalt for Students.**— .^«a/>«^. 



HINTS ON THE PRESERVATION OF FISH, 

IN REFERENCE TO FOOD SUPPLY. 

By J. COSSAR EWART, M.D., F.R.S.E., 
Regius Professor of Natural History, University of Ediabmgh. 

In Crown 8to. Wrapper, 6d. 
LONDON: EXETER STREET, STRAND. 



BOIBNTIFIC AND TEOHNOLOOWAL WORKS. u 

Second Edition, Rtvised. Royal Svo, IVtih numerous Illustrations and 
13 Lithographic Plates. Handsome Cloth. Price yis. 

BRIDGE-CONSTRUCTION 

(A PRACTICAL TREATISE ON) : 

Being a Text-Book on the Constraction of Bridges in 
Iron and Steel. 

FOR THE USE OF STUDENTS, DRAUGHTSMEN, AND ENGINEERS. 

BY 

T. CLAXTON FIDLER, M. INST. C.E., 

Prof, of Engineering, University College, Dundee. 



"Mr. FiDLEB^s SUCCESS arises from the combinatiou of experience and 
SIMPLICITY OF TREATMENT displaced on every page. . . . Theory Ib kept in 
subordination to practice, ana his book is, therefore, as useful to girder-miucers 
as to students of Bridge Construction."— (TAd *^ Architect" on the Second 
Edition.) 

" Of Ute years the American treatises on Practical and Applied Mechanics 
have taken the lead . . . since the opening up of a vast continent has 
given the American engineer a number of new bridge- problems to solve 
. . . but we look to the PRESENT Treatise ON Bridge-Construction, and 
the Forth Bridge, to bring us to the front again.**— i^n^neer. 

*' One of the vert best recent works on the Strength of Materials and its 
application to Bridge-Construction. . . . Well repays a careful Study.*' — 
Rr^nineering. 

"An indispensable handbook for the practical Engineer."— JfoAcre. 

" An admirable account of the theory and process of bridge-design, at once 
SGXBNTinc AND THOROUOHLY FBACTiCAL. It IS a book such as WO have a right 
to exi)ect from one who is himself a substantial contributor to the theory of 
the subject, as well as a bridge-builder of Tej^ute.^^—ScUwrday Review. 

**Thia book is a model of what an engineering treatise ought to be."^ 
Jndtutriet. 

** A acDQiTino tbbatisb of gbxat hsrit.*'— TFeiemJmfor Renew, 

'*0f recent text-books on subjects of mechanical science, there has 
appeared no one more able, kxhaustiyx, or ussiTJLthan Mr. daxton 
Midler's work on Bridge-Construction. "—vSeotnyioft. 

UONDON: EXETER STREET, STRAND. 



12 CHARLB8 GRIFFIN Jk C0:8 PUBLI0ATI0N8. 



Ore and Stone jWifiing 

(A Text-Book of): 

FOR THE USE OF MINE-OWNERS, MINE-MANAGERS, 

PROSPECTORS, AND ALL INTERESTED IN 

ORE AND STONE MINING. 



CLEMENT LE NEVE FOSTER, D.Sc., F.R.S., 

PROFESSOR OK MINING. ROYAL COLLEGE OF SCIENCE; H.1I. INSPECTOR OF MINES. 

In Large 8vo. With very numerous Illustrations. 

[Griffiths Mining Series. 



GIBB (Thos., Associate, Royal School of Mines): 

COPPER (THE METALLURGY OF): Being one of the New 
Metallurgical Series, edited by Professor Roberts- Austen, C.B., F.R.S. 
(Seep. 26.) 

GRIFFIN (John Joseph, F.CS.) : 

CHEMICAL RECREATIONS: A Popular Marnud of Experimental 
Chemistry. With 540 Engravings of Apparatus. TttUk EdtHcm^ Crown 
4to. Cloth. 

Part L— Elementary Chemistry, 2/. 

Part II.— The Chemistry of the Non-Metallic Elements, including a 
Comprehenaire Comae of Class Ezperimcnts, 10/6. 
Or, complete in one volume, doth, gilt top^ • . 13/6. 

LONDON: EXETER STREET, STRANa 



BQIENTIFIQ AND TBOHNOLOOIOAL WOBKS. 13 

Issued in two shales. Large Crown 8vo, Cloth, for Office use, 8s. 6d. Also 
Printed on Thin Paper and Bound in Leather, for the Pocket, 8s. 6d. 

Electrical Engineers' Price-Book 

FOR THE USE OF 

£leetrieal, Civil, Marine, and Borougrh Engineers, Local 
Authorities, Architects, Railway Contractors, &c, &a 

EDITED BY 

H. J. DOWSING, 

Member o/ih* Institution of Electrical Engineers; of the Society of Arts; of the Loud^m 
Chamber of Commerce, &*c, 

OENZSRAL CONT1BNT8. 

Part I.— PRICES AND DETAILS OF MACHINERY AND APPARATUS; 
Buildings for Generating Station; Generating Plant (Steam, Gas, and Oil Engines); 
Djrnamos (Continuous, Alternating, and Exciters); Storage; Measuring, Regu- 
lating, and Controlling Apparatus; Distributing Plant, Public ^d Private; 
Meters; Warming, Cooking, and Ventilating by Electricity; Electromotive 
Power; Electric Railways, Tramways, Launches, Cranes. &c.; Electro- Deposition; 
Electric Smelting and Welding; Primary Batteries; Telephones; Telegraphy; 
Electric Bells ; Lightning Conductors; Miscellanea. 

Part II.— USEFUL INFORMATION CONCERNING THE SUPPLY OF 
ELECTRICAL ENERGY; Complete Estimates; Reports, Rules and Regu- 
lations. Useful Tables, &c. ; and General Information regarding the carrying out 
of Electrical Work. 

"The Electrical Pricb-Book rbmovbs all mystery about the cost of Electrical 
Power. By its aid the expense that will be entailed by utilising electricity on a Large or 
small s::ale can be discovered. , . . Contains that sort of information which is most oflen 
required in an architect's office when the application of Electricity is being considered."— 
Aixhitect. 

" The value of this Electrical Price-Book cannot BE ovBR-BSTiMATBD. . , . Will 
save time and trouble both to the engineer and the business maau**'-MacMmery^ 



GURDEN (Richard Lloyd, Authorised Surveyor 

for the Governments of New South Wales and Victoria) : 

TRAVERSE TABLES : computed to Four Places Decimals for eroy 
Minute of Angle up to 100 of Distance. For the use of Surveyors and 
Engineers. Third Edition, Folio, strongly half-bound, 2 1/. 

%* Published with Concurrence of the Surveyors- General for New SoMtM 

IVaies and yictoria. 

** Those who have experience in exact Survey-work will best know how to appnciato 
the enormous amount of labour represented by this valuable book. The ocnnpatatioiis 
enable the user to ascertain the sines and cosbes for a distance of twelve miles to within 
half an inch, and this by rbpbrbncb to but One Tablb. in place of the usual Fifkecn 
minute computations required. This alone is evidence of the assistance which the Tables 
ensure to every user, and as every Surveyor ia active practice has felt the want of sndh 
—— • , few knowing of their publication will remam without them,**— Engineer. 



LONDON: EXETER STREET, STRAND. 



H OBABLMS ORIFriN S 00.'8 rUBLlOATIOSB. 

Griffin's Standard Publications 

EMaiH££S0, ELECTRICIANS, ABCHITECTS, BUILDERS, 
NAVAL CONSTRUCTORS, AND SURVEYORS. 







FAOm 


Appliad Heebanies, . 


Pbof. Bakkink, 


. 23 


„ (Student's), . 


Browne, Jamieson, 


.6,17 


Civil Engrineeringr, . 


pRor. Kankine, 


23 


Bridgre-Construction, , 


Prof. Fidler, . 


11 


Desigrn of Struetures, . 


S. Anolin, . 


a 


Sewagre Disposal Works, 


Santo Crimp, 


& 


Traverse Tables, . 


R. Gurden, 


13- 


Marine Engfineering:, 


A. E. Seaton, - 


2^ 


StabUity of Ships, 


Sib E. J. Rbed, 


25 


The Steam-Engrine, . 


Prof. Rankine, 


23 


(Student's), 


Prof. Jamibson, 


17 


Dynamos, 


R. E. Crompton, 


^ 


Gas, Oil, and Air-Engines 


J Bryan Donkin, 


10 


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T. W. Traill, . 


3(> 


„ Managrement, 


R. D. MuNRO, . 


1^ 


Fuel and Water (for 


f Schwackhofer and 
( Browne, 


. 2a 


Steam Users), 


Machinery and Millwork, 


Prof. Rankine, 


. 23 


Hydraulic Ma(diinery, . 


Prof. Robinson, 


27 


Metallurgrical Machiner 


y, H. C. Jenkins, 


26 


Useftil Rules and Tables 


r Profs. Rankinb and 
\ Jamieson, 


. 23 


for Engrineers, Ac., . 


Electrical Pocket-Book, 


MuNRO AND Jamieson 


, 20 


. Electrical Price-Book, . 


H. J. Dowsing, . 


13 


Marine Engineers' Pock 


e1^ 




Book, . . . . 


SeATON AND ROUNTHWAI 


TE,29 


Nystrom's Pocket-Book 


y Dbnnis Marks, . 


20 


Surveyors' Pocket-Bool 


C, Crimp and Cooper, . 


8 



LONDON: EXETER STREET, STRAND. 



a(^M»nwja akd racHNOLoaiCAL works. 15 

in Large Zvo^ with BlmiraiUms and Foliing'PlaUs, i(v. €tL 

BLASTIIsrO: 

A Handbook for the Use of Engineers and others Engaged in 
Mining, Tunnelling, Quarrying, &c. 

By OSCAR GUTTMANN, Assoc M. Inst. C.E. 

Mtmher cf tht Seeieiies cf Civil Engineers and Architeets of Vienna and Bndapest, 
Cerretfonding Member e/the Imp, Roy, GeeUgieai Inttitniifin qfAtairia^ 6^. 

V Mr. GuTTMAmr's BkuHftg U the only woik on die nibject which ghrce nt once ftill 
tnronnation as to the Ninv mbthoos adopted since the introduction of Dvnaintte^ and, at the 



.»»^ time, the results of mahy ybars practical kxfbribncb both in Sf ining Work and in 
the Manufacture of Explosives. It therefore presents in concise form all that has been prwed 
ffood in the various methods of procedure. The lUuatrations form a special and valnabia 
watun of the woik. 

Gbkeral Contents.— Historical Sketch— Bhisting Materials— Blasting Pofw- 
<ier — ^Various Powder-mixtures — Gan-cotton — ^Nitro-glycerine and Dynamite — 
Other Nitro-compounds — Sprengel's Liquid (acid) Explosives— Other Means of 
Blasting — Qualities, Dangers, and Handling of Ezptosives — Choice of Blasting 
Materials — Apparatus for Measuring Force — Blasting in Fiery Mines — Means of 
Iniiting Charges — Preparation of Blasts — Bore-holes — MAchine-drillinff — Chamber 
Mines — Charging of Bore-holes — ^Determination of the Charge — Blastmg in Bore- 
holes—Firing — Straw and Fuze Firing— Electrical Firing— Substitutes for Electrical 
Firing^Results of Working^Various Blasting Operations — Quarrying — Blasting 
Masonry, Iron and Wooden Structures — Blasting in earth, under water, of ice, Ac. 

"This ADMiRABLB wofk."— C^Zfirrf GMordiem, 

** Should prove a vade^meemn to Mining Engine ers and all engaged in pisactical work.** 
^Jrmamd Ceal Trades Retnew. 



With Numerous Illustrations. JPrice I2X. 6d, 

PAINTERS' COLOURS, OILS, AND VARNISHES: 

By GEORGE H, HTJRST, F.C.S., 

Uenber of the Society of Chemical Industry ; Lecturer on the Technology of Paintera' 
Colours, Oils, and Varnishes, the Municipal Technical School, Manchester. 

Ornbral Contents. — Introductory— Thb Composition, MANUPACTmE, 
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—Lakes — Colour and Paint Machinery— Paint Vehicles (Oils, Turpentine, &c., 
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LONDON: EXETER STREET, STRAND. 



i4 OHARLM8 QBiFFlN S OO.'S FUBUCATIOMB. 

COAL-MINING (A Text-Book of): 

fOn THE WE Of COLUERY MAMAGEM AMD OTHEn 
EMQAQED IN COAL-MIIIIIIQ. 

BT 

HERBERT WILLIAM HUGHES. F.G-S, 

Amoc Royal School of Miaes, Crrtifiratcri Coilioy JfiBigiir 

Second Edition. In Demy 8tv, Handsome Clctk, Wiik very Nmmurmts 

Illustrations t mostly reduadfrom Working Drawings, iSf. 

*' The details of colliery work ha^v been fully described, on the groimd that 

collieries are more often made kemunxkative by perfection in smaix matters 

than by bold strokes of engineering. ... It iineqiiently happens, in particiilar 

localities, that the adoption of a combination of small improvements, any oC 

which viewed separately may be of apparently little value, turns an unprofitable 

concern into a paying one." — Extract from Author's Preface. 

GENERAL CONTEITTS. 
(Holefy: Rockii — Faolts— Order of SucccKion--Carbonifcrotts SyslnB in ftitaia. 
Oo«l : Definition and Formation of Coal— Clauilication and Cominerctal Valne of Coals. 
BMtfOh for Goal : Boring— rariotu appliamces used— Devices employed to meet Diflkiihie» 
of deep Doring— Special methods of Borinp;— Mauber & Piatt's, American, and Diainood 
ayftem«— Accident* in Boring— Cost of Bonng— Use of Boreholes. Breaking Ofoimd: 
Tools— Transmission of Power: Compressed Air, Electricity— Power Machine Drills — Coai 
Cutting by Machinery Cost of Coal Cutting— Explosives— Blasting in Dry and Dusty 
Mines— Blasting by Electricity— Various methods to supersede Blasting. Sinking: 
Position^ Form, and Sixe of shaft— Operation of getting down to *' Stone^hcad "—Method of 
proceeding afterwards— Lining shafu— Keeping out Water by Tubbing— Cost of Tubbing — 
Sinking by Boring— Kind- Chaudron, and Lipmann methods— Sinking through Quicksands 
—Cost of Sinking. PreUmlnary Operatloos : Driving underground Roads— Supportii^ 
Roof: Timbering, Chocks or Cogs, Iron and Steel Stippotts and Masonry— Amngement of 
Inoet. Methoas of Working: Shaft. Pillar, and Subsidence— Bord and Pillar System— 
I^uicashire Method— Lonewall Method— Double Stall Method— Working Steep Seani»— 
Working Thick Seams- Working Seams lying near together— Spontaneous Oimbustion. 
Baulage: Rails— Tut>s— Haulage by Horses— Self-acting Inclines— Direct-actine Haulage 
—Main and Tail Kope— Kndless Chain- Endless Kope— Comparison. Winding: Pit 
Frames — Pulleys— Cages— Ropes— Guides— Engines-Drums — Brakes— Counterbalancing — 
Expansion— Condensation— Compound Engines— Prevention of Overwinding— Catches ac pit 
top— Changing Tubs— Tub Controllers— Signalling. Pumping: Bucket and Plunger 
Pumps — Supporting Pipes in Shaft — Valves — Suspended lifts for Sinking — Cornish and 
Bull Engines— Davey l)ifrerential Engine- Worthington Pump— Calculations as to sixe of 
Pumps— Draining Deep Workings— Dams. Ventilation: Quantity of air required — 
Gases met with in Mines— Coal-dust— Laws of Friction— Production of Airnmrrents — 
Natural Ventilation— Furnace Ventilation— Mechanical Ventilators— Efficiency of Fans — 
Comparison of Furnaces and Fans— Distribution of the Air-current— Measurement of Air- 
currents, lilghiisg: Naked Lights — Safety Lamps— Modem Lamps — Conclusions — 
Locking and Cleaning Lamps- Electric Light Underground— Delicate Indicators. Work8> 
at Surfftce; Boilers— Mechanical Stoking— Coal Conveyors— Workshops. Prepazation 
of Goal for Market: General Considerations— Tipplers— Screens— Varying the Sixes made 
by Screens— Belts— Revolving Tables— Loading Shoots— Typical Illustrationsof the arrange- 
ment of Various Screening Establishments— Coal Washing— Dry Coal Cleaning -Briquettes. 

" Quite THK DBST BOOK of its kind ... as practical in aim as a book can be . . . 
touches upon every point connected with the actual working of collieries. The illustrations 
are kxckllei*t."—j1 tAena^m. 

*' A Text-book on Coal- Mining is a f^reat desideratum, and Mr. Hughes possesses 
ADMiRABLK qi;ai.ificatioks for supplying it. . . . We cordially recorunend the work." 
—Colliery Guardian. 

••Mr. HuGHRS has had opportunities for study and research which fall to the lot of 
hut few men. If we mistake not, his text- book will soon come to be regarded as the 
STANDARD WORK of its kind."— Zf»>w/«^A<7W» Daily Gazettr. 

%* JV(9/#.— The first large edition of this work was exhausted within a few months of 
publication. 

LONDON : EXETER STREET, STRAND. 



aOIMNTIFW AND TXCHNOLOQIOAL WORKS. 17 

WOBKS BY 
ANDREW JAMIESON, M.INST.C.E., M.I.E.E., F.R.S.E., 

Pro/tuor of EUctrUal Engitufrtngr, The Gkugviu and West •/ Scotland 
Ttckniemi ColUgt. 



PB0FE3S0B JAMIESOK'S ADVANCED MANUALS. 

In Large Crown %vo. Fully Illustrated, 

1. STEAM AND STEAM-ENGINES (A Text-Book on). 

For the Use of Students preparing for Competitive Examinations. 
With over 200 Illustrations, Folding Plates, and Examination Papers. 
Ninth Edition. Revised and Enlarged, 8/6. 

" Professor Jamieson fascinates the reader by his clbarniss of coNCsmoN ani> 
SIMPLICITY OK BXPRKSSioN. His treatment recalls the lecturing of Faraday."— yf/AnurwM. 

" The Bbst Book yet published for the use of Students."^£^>(#«r. 

" Undoubtedly the most valuablk and most complbtk Hand-book on the iulject 
that now exists." — Marine EntiKeer. 

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8. APPLIED MECHANICS (An Advanced Text-Book on). 

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PROFESSOR JAHIESOM'S INTRODUCTORT llANUALS. 

In Crown Svo, Cloth, With very numerous Illlustratiotis and 
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1. STEAM AND THE STEAM-ENGINE (Elementary Text- 

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** Quite the right sort op book."— f «</j»*irr, 

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" A capital text-book . . . The diajo^ms are an important feature."— .SVA<9<7//NAr/^r. 

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3. APPLIED MECHANICS (Elementary Text-Book on). 

specially arranged for First-Year Students. 3/6. 

" NotHing is taken for granted. . . . The work has very high qualities, which 
may be condensed into the one word ' clbar.' " — Science and Art. 



POCKET-BOOK of ELECTRICAL RULES and TABLES. 

FOR THE USE OF ELECTRICIANS AND ENGINEERS. 

Pocket Size. Leather, 85. 6d. 7mth Edition, revised and enlarged. 

(See under Munro and /amisson, ) 

LONDON: EXETER STREET, STRAND. 




tA COUPLES GUFNN S 00.8 PXTBLICAJTIOVS. 

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MANUAL OF DYEING: 

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flaad of the Chemistry and Dyeing Department ef Late Head of the Chemistry and Dyeing Depatment for 
the Tedmieal School. Mancheater; Editor of "The the Technical College, Bradford ; Memher of Council 
Journal of the Society of Dyers and Colourists ; " ot the flooiety uf Dyma and Ooloulste ; 

And RICHARD LOEWENTHAL, Ph.D. 



General Contents.— Chemical Technology of the Textile Fabrics- 
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LONDON : EXETER STREET, STRAND. 



8CJBNTIFIC AND TECHNOLOCUCAL WORKS. 19 

ELECTRO-METALLURGY (A Treatise on): 

Embracing the Application of Electrolysis to the Plating, Depositing, 

Smelting, and Refining of various Metals, and to the Repro- 

daction of Printing Surfibces and Art* Work, &c. 

By WALTER G. M'MILLAN, F.I.C., i^.C.S., 

C9k«mi(( and MeiaUurgui to the Cotgipore Foundrv and Shelt-Factory ; Latt Demonstrator 
qfMetailurgp in Kin^e College, London. 

With nmneroos Illustrations. Large Crown 8vo. Cloth, lOs. 6d. 



General Contents.— Introductory — Sources of Current— General Condition 
to be observed in Kleotro-Plating— Plating Adjuncts and Disposition of Plant — 
Cleansing and Preparation of Work for the Depositing-Vat, and Subseqaent Polishing 
of Plated Goods — Electro -Deposition of Copper — Electrotvping — Electro- DepositioD 
of Silver— of Gold— of Kickel and Cobalt— of Iron— of Platinum, Zinc, Cadmium, 
Tin, Lead, Antimony, and Bismuth ; Klectro-chromy— Electro- Deposition of Alloys — 
Electro- ftletallurgical Extraction and Refining rrocesses — Recovery of certflix> 
Metals from their Solutions or Waste Substances— Determination of tne Proportion 
of Metal in certain Depoi^iting Solutions— Appendix. ' 

" This excellent treatise, . . . one of the best and most cOMPLEns. 
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" This work will be a standard. "—J^cii?€Z/€r. 

"Any metallurgical process which reduces the cost of production 
must of necessity prove of great commercial importance. . . . W& 
recommend this manual to all who are interested in the practical 
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Second Edition. ^Enlarged, arid veryfvUy Illustrated, Cloth, 4s, 6d. 

STEAM - BOILERS! 

THEIR DEFECTS, MANAGEMENT, AND CONSTRUCTION. 
By R D. MUNRO, 

Enffineer ^fihn Seotiish Boiler Jnturanoe and Engine Inspection Company. 
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General Contents. — Explosions caused by Overheating of Plates : (a) 
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Overloaded Safety- Valves — Area of Safety-Valves — Explosions caused by 
Conoflion^-ExploMonB caosed by Defective Design and Construction. 

'* A valuable companion for workmen and engineers engaged about Steam 
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LONDON : EXETER STREET, STRAND. 



30 QHARLBS QRIFFIN S CO.'S PUBLWATIONB. 

MUNBO k JAMIESON'S ELECTEICAL POCKET-BOOK. 

Tenth Edition, Revised and Enlaxged. 

A POCKET-BOOK 

OF 

ELECTRICAL RULES & TABLES 

FOR THE USE OF ELECTRICIANS AND ENGINEERS. 
BY 

JOHN MUNRO, C.E., & Prof. JAMIESON, M.Inst.C.E., F,R.S.K 
With Numerous Diagrams, Pocket Size. Leather, 8s. 6d. 



GENERAL CONTENTS. 

Units of Measurement. , Electro-Metallurgy. 

Measures. . Batteries. 

Testing. ! Dynamos and Motors. 

Conductors. | Transformers. 

Dielectrics. Electric Lighting 

Submarine Cables. ! Miscellaneous. 

Telegraphy. ; Logarithms. 

Electro-Chemistrt. Appendices. 

" WoNDBXFULLV Pbkpbct. . . . Worthy of the highest ooaunendatioo we ctti 
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MUNRO (J. M. H., D.Sc, Professor of Chemistry, 

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AGRICULTURAL CHEMISTRY AND ANALYSIS : A Prac- 
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NYSTROM'S POCKET-BOOK OF MECHANICS 

AND ENGINEERING. Revised and Corrected by W. Dennis Marks, 
Ph.B., C.E. (YALE S.S.S.), Whitney Professor of Dynamical Engiueering, 
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Edition, Revised and greatly enlarged. 

LONDON: EXETER STREET, STRAND. 



8CIBNTIFIC AND TECHNOLOGICAL WORKS. zi 

Demy Sua, Handsome cloth, 18s. 

Physical Geology and PalMtology, 

OJV THE BASIS OF PHILLIPS. 

VI 

HARRY GOVIER SEELEY, F.R.S., 

PROFESSOR OF CBOCRAFHY IN KING'S COLLBCB, LONDON. 

VUtb yrontldpiece in CbcomooXitbOdtapbSt anb Jlluatrationa* 



** It is impossible to praise too highly the research which Professor Seeley's 
' Physical Geology ^ evidences. It is far more than a Text-book — ^it is 
a Directory to the Student in prosecuting his researches." — Prtsidential Ad* 
dress to the Geological Socitty^ 1885,^ Rev. Prof. Bonnty, D.Sc^ LL.D., F.R.S. 

** Professor Seeley maintains in his ' Physical Geology ' Uie high 
reputation he already deservedly bears as a Teacher." — Dr. Henry Weiod- 
ward, F.R.S,, in the '< Geological MagaMmtJ" 

** Professor Seeley's work includes one of the most satisfactory Treatises 
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afibrd to be without it.*' — American Journal of Engineering. 



Demy 8vo, Handsome doth, 34^. 

StratigrapMcal Geology & Falsontology, 

OJf THE BASIS OF PHILLIPS. , 



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THB NATURAL HIST. DRPARTMBNT. BRITISH MUSEUM, I.ATS PAL^BONTOLOCIST TO T 

CBOIjOCICAI. survey of CRBAT BRITAIN, PAST PRBSIOBKT OF THB 

CBOLOCICAL SOCIBTY. BTC 

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%• Prospectus of the above important work— perhaps the most elaborate of 
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'* No sudi oompendium of geoloKical knowledge has ever been bronght together befiMre.***— 
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OF mMrmaMHcm.**-'Athememm, 

LONDON: EXETER STREET, STRAND. 



32 CHARLES GRiniN S CO^B PUBLICATIONS. 

Third Edition, if«mMef hy Mr. H, Bauerman^ F.O,S. 

ELEMENTS OP METALLURGYs 

A PRACTICAL TREATISE ON THE ART OF EXTRACTING METALS 

FROM THEIR ORES. 

By J. ARTHUR PHILLIPS, M.Inst. C.E.,F.O.S., F.G.S., &c.. 

And H. BAUERMAN, V.P.G.S. 

With Folding Plates and many Ulustrationa. Large 8vo. 
Handsome Cloth, 368. 



GENERAL CONTENTS. 



Refractory Materials. 

Fire-Clays. 

Fuels, &c. 

Alumioiam. 

Copper. 

Tin. 



Antimony. Iron. 

Arsenic. Cobalt. 

Zinc. NickeL 

Mercury. Silver. 

Bismntn. Gold. 

Lead. Platinum. 

*»'* Many notablx additions, dealing with new Processes and Developments, 
will be found in the Third Edition. 

" Of the Third Edition, we are still able to say that, as a Text-book of 
Metallurgy, it is the best with which we are acquainted.*' — Engineer, 

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** A work which is equally valuable to the Student as a Text-book, and to 
the practical Smelter as a Standard Work of Reference. . . . The Illustra- 
tions are admirable examples of Wood Engraving.'*— C'AeTitica/ Keum, 



POYNTING (J. H., Sc.D., F.R.S., late Fellow 

of Trinity College, Cambridge; Professor of Physics, Mason CoU^c, 
Birmingham) : 

THE MEAN DENSITY OF THE EARTH: An Essay to 
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and THOMSON: TEXT-BOOK OF 



PHYSICS. (See under Thomson). 



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sonarriFio Ajrj> facrBSOLoaicAL wo*a. 2$ 
WORKS BY 

J. MAGQOORM RAMKIME, LL.D., F.R.S., 

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THOBOUOHLT BSVISED BT 

W. J. MIL LAB, C.E., 

Secretary to the Institute of Engineers and StiipbuHders in Seetland, 



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Part I. Papers relating to Temperature, Elasticity, and Expansion of 
Vapours, Liquids, and iSolids. Part II. Papers on Energy and its Trana^ 
formations. Part IIL Papers on Wave-Forms, Propulsion of Vessels, ftc. 

With Memoir by Professor Tait, M. A. Edited by W. J. Millar, C.E. 
With line Portrait on Steel, Plates, and Diagrams. 

" No more enduring Memorial of Professor Rankine could be devised than the publica- 
tion of the^c papers m an accessible form. . . . The Collection is most valuable pa 
account of the nature of his discoveries, and the besiuty and completeness of his analTiis. 
... The Volume exceeds in importance uxf voric in the same depaitmcot pubUahed 
in our time "—.4 rckiUct, 



REDGRAVE (Gilbert R., Assoc. Inst. C.E.): 

CEMENTS : A Practical Hand-Book on their Manufacture, Properties, 
Testing, &c. {Griffin's Technological Manuals), 



A TREATISE ON. 

The Geographieal Distribution, Geologfieal Oceurrenee» 

Chemistry, Production, and Refining of Petroleum; 

its Testing, Transport, and Storage, and the 

Legislative Enactments relating thereto ; 

together with a description of 

the Shale Oil Industry, 

BY 

BOVERTON REDWOOD, F.R.S.R, F.I.O., Assoc. Inst. C.E., 

Hon. Corr. Mem. of the imperial Russian Teefinicai Society ; Mem. of 

the American Chemical Society; Consulting Adviser to the 

Corporation of London under the Petroleum Acts, 

Ac., Ac. 

ASSISTED BT 

GEO. T. HOLLOWAY, F.LC, 

Associate, Royal School of Mines. 
In Large 8vo. With Maps and Illustrations. 

%* Sppcial Fkatorrb of Mr. Rrdwood'b Work are (1) the hitherto nnpublished do* 
■cnptiona or the Umdrvklopbd Soukcks of Pktroleom in ▼arioas parts of the world, which 
the author is in an exceptiooaily favourable posiiioo to give: aud 02) Bales for the Tisraro, 
Tkaksfort, and Storaqb of Petroleum -t'lene subjects are fully dealt with from the 
point or Tiew of Leoislatiok and the Pkecautioks which experience in this and oth«r 
countries has shown to be necessary in the interests of public safety. 

LONDON: EXETER STREET, STRAND. 



80IENT1FI0 AND TECHNOLOGICAL W0BK8. 15 

Rontti 8»o, HandsQm§ Clotk, 259. 

THE STABILITY OF SHIPS. 

SIR EDWARD J. REED, K.C.B., F.RS., M.P., 

■MIGHT OF TKB IMmiAL OKDBSS OF ST. STANILAU8 OF KI7SSIA; FXANCIS JOtBPH OT 

AUSTkia; mbdjidib of tqrxby; and sising sun of japan; vio- 

FKBSIDBNT OF THB INSTITUTION OF NAVAL ASCHITBCTS. 

With numtnms lUustratwns and Tablet, 

This woric has been written for the purpose of pladng in the hands of NaTsl Constmctots, 
Shipbuilders, Officers of the Royal and Mercantile Marines, and all Students of Naval Sdence, 
a complete Treatise upon the Stability of Ships, and u the only work in the English 
Language dealing exhaustively with the subject. 

In order to render the work complete for the purposes of the Shipbuilder, whether at 
home or abroad, the Methods of Calculation introduced by Mr. F. K. Barnbs, Mr. Gkav, 
Jl. Rbbch, M. Dayuaru, and Mr. Bbnjamin, are all given separateljr, illustrated Ij 
Tables and worked-out examples. The book contains more than aoo Diagrstms, and is 
illustrated by a large number of actual cases, derived from ships of all descriptions, but 
ospedally from ships of the Mercantile Marine. 

The work will thus be found to constitute the most comprehensive and exhaustive Treatisa 
hitherto presented to the Profession on the Science of the Stability of Ships. 



" Sir Edward Rbbd's ' Stability of Ships ' is inyaluablb. In it the Studbnt, new 
to the subject, will find the path prepared for him, and all difficulties explained witn dio 
utmost care and accuracy ; the Ship-draughtsman will find all the methods of adcuhui<m at 
present in use fully explained and Ulustr^ed, and accompanied by the Tables and Forms 
employed ; the Shipowner will find the variations in the Subility of Ships due to differences 
in forms and dimensions fully discussed, and the devices by which the state of his ships under 
all conditions may be graphically represented and easily understood ; the Naval Architbct 
will find brought together and ready to his hand, a ma^ of information which he would other- 
wise have to seek in an almost endless variety of publications, and some of which he would 
possibly not be able to obtain at all elsewhere."— 3/ImmsA(^ 

"This important and valuable work . . . cannot be too highly recommended to 
all connected with shipping interests." — Irm$, 

" This VERY IMPORTANT TREATISE ... the MOST INTBLLIGIBLB, INSTBUCTITB, and 

COMPLETB that has ever Appealed.'*— Jvature. 

"The volume is an essential onb for the shipbuilding pr6k$aaaa.**-^H^etimmtUr 
Htvinth 



RICHMOND (H. Droop, F.C.S., Chemist to the 

Aylesbury Dairy Company) : 

DAIRY CHEMISTRY FOR DAIRY MANAGERS : A Practical 
Handbook. {GriffifCs Technological Manuals,) 

LONDON: EXETER STREET, STRAND. 



s6 OmJkMLMa 9RimX A OO.'S PUBLKATWSa. 

STANDARD WORKS OF REFERENCE 

FOR 

Metallurgists, Mine-Ownevs, Assayen, Mnvfticlnrers, 

and all interestecL in the development of 

the Metallurgical Industries. 

EDITED BY 

W. C ROBERTS-AUSTEN, CB., F.R.S, 

CHSiaST AND AS6AYEX OP THE ROYAL MINT ; PROFESSOR OF METALLURGY Bf 

THE ROYAL COLLEGE OF SCIENCE. 

/m Lmx* Bw, HatuUetiu Cloth. With lUiulniiiotu, 



No-w Ready. 

1. nrraiODUCTIOM* to the STUDY of VSniAl^TTBLOtY. 

By the Editor. Third Edition. 

*' No English text-book at all approaches this in the completeness with 
which the most modern views on the subject are dealt with. Professor Austen's 
volume will be invaluable, not only to the student, but also to those whose 
knowledge of the art is far advanced." — Chemical News. 

" Invaluable to the student • . . Rich in matter not to be readily found 
elsewhere." — Athenaum, 

" This volume amply realises the expectations formed as to the result of the 
labours of so eminent an authority. It is remarkable for its originality of con- 
ception and for the large amount of information which it contains. . . . We 
recommend every one who desires information not only to consult, but to study 
this work." — Engineering. 

*• Will at once take front rank as a text-book. "--5«<w« and Art. 

" Prof. Roberts-Austen's book marks an epoch in the history of the teaching 
of metallurgy in this country." — Industries. 



WiU be rubtiihed at Short Intervals. 

2. aOIiD (The Metallurgy of). By Thos. Kirke Rose, 

Assoc. R.S.M., F.I.C., of the Royal Mint. 

3. COPPEB (The Metallurgy of). By Thos. Gibb, Assoc. 

R.S.M., F.I.C., F.C.S. 

4. IBON and STEEL (The MetaUurgy of). By Thos. 

Turner, Assoc. R.S.M., F.I.C, F.C.S. 

6. METALLUBQICAL MAGHINEBY: the Application of 
Engineering to Metallurgical Problems. By HENRY Charles JENKINS, 
Wh.Sc., Assoc. R.S.M., Assoc. M. Inst. C.E., of the Royal Mint. 

e. AIiLOYS. By the Editor. 

* ^ Other Volumes in Preparation, 

LONDON: EXETER STREET, STRAND. 



8CISNTIFI0 AND TBCHNOLOOIOAL WORKS. 27 

SEGOJ^D EDITIOJ^, Bevised and Enlarged. 
In Large 8vo, Handsome cloth, 34s. 

HYDRAULIC POWER 

AND 

HYDRAULIC MACHINERY. 

BT 

HENRY ROBINSON, M. Inst. C.E., F.G.S., 

FBLLOW OP king's COLLBCB, LONDON; PROF. OP CIVIL BNGIMBBKIMG, 

king's collbgk, ktc., etc. 

TSAitb numetouB TlQloodcute, aiU) Si^t^^ninc p[ate0» 



General Contents. 

Dischai^e through Orifices— Gauging Water by Weirs — Flow of Water 
through Pipes — The Accumulator— The Flow of SoUds— Hydraulic Presses 
and Lifts — Cyclone Hydraulic Bating Press — Anderton Hydraulic Lift — 
Hydraulic Hoists (Lifts)— The Otis Elevator— Mersey Railway Lilts— City 
and South London Railway Lifts — North Hudson County Railway Elevator — 
Lifts for Subways — Hydraulic Ram — Pearsall's Hydraulic Engine— Pumping- 
Eogines — ^Three- Cylinder Engines — Brotherhood Engine — Rigg*s Hydraulic 
Engine — Hydraulic Capstans— Hydraulic Traversers — Movable Jigger Hoist — 
Hydraulic Waggon Drop — Hydraulic Jack — ^Duckham's Weighing Machine — 
Shop Tools— Tweddells Hydraulic Rivetter — Hydraulic Joggling Press — 
Tweddell's Punching and Shearing Machine — FUuiging Machine — Hydraulic 
Centre Crane — Wrightson*s Balance Crane — Hydraulic Power at the Forth 
Bridge — Cranes — Hydraulic Coal-Discharging Machines — HydrauUc Drill — 
Hydraulic Manhole Cutter — Hydraulic Drill at St. Gothard Tunnel — Motors 
with Variable Power — Hydraulic Machinery on Board Ship — Hydraulic Points 
and Crossings — Hydraulic Pile Driver — Hydraulic Pile Screwing Apparatus — 
Hydraulic Excavator— Ball's Pump Dredger — Hydraulic Power applied to 
Bridges — Dock-gate Machinery — Hydraulic Brake — Hydraulic Power applied 
to Gunnery — Centrifugal Pumps — Water Wheels — Turbines— Jet Propulsion — 
The Gerard-Barr^ Hydraulic Railway — Greathead's Injector Hydrant — Snell's 
Hydraulic Transport System — Greathead's Shield — Grain Elevator at Frank- 
fort — Packing — Power Co-operation — Hull Hydraulic Power Company — 
Londoa Hydraulic Power Company — Birmingham Hydraulic Power System 
— ^Niagara Falls — Cost of Hydraulic Power — Meters — SchOnheyder*s Pressure 
Regulator — Deacon's Waste- Water Meter. 

" A Book of sreat PxofeMioiial UteluliKas.**— /tvn. 

*«* The Sxcovo Editiov of the above Important wortc has been thoroughly revised and 
broogfat up to date. Many new fnll-page Plates have been added— the Dnmber being 
tncreaeed from 43 in the First Edition to 6» in the piesent Full ProepeettB, giving a 
description of the Plates, may be had on appUoatioa to the Pablishers. 

LONDON: £X£T£R STJIEET, STRAND. 



a8 CHARLES QRIFFIN A CO.'S PUBLICATIONS. 

SCHWACKHOFER and BROWNE: 

FUEL AND WATER: A Manual for Users of Steam and Water. 
By Prof. FRANZ SCHWACKHOFER of Vienna, and WALTER 
R. BROWNE, M.A., C.E., late Fellow of Trinity Coll^;e, Cambridge. 
Demy 8yo^ with Numerous Illustrations, 9/. 

GsNBitAL CoNTRNTs.— Heat and Combustion— Fuel^ Varieties of— flnne Amogc- 
menta : Furnace, Flues, Chimney — The Boiler, Choice of — Varieties — Feed-water 
Heaters— Steam Pipes^— Water : Composition, Punfication~Prevention<^ Scale, &c, &c. 

"The Section on Heat is one of the best and most ludd erer written.**— ^n^iuvr. 

" Contains a vast amount of useful knowledge. . . . Cannot fiul to be valnabls t» 
thousands compelled to use steam power."— AaxAimi^ Engitutr, 

" Its practical utility is beyond question."— if m»^ JoumoL 



VORKS by Prof. HUIBOLDT SEXTOM, F.LC, F.C.S., F.ILS.K, 

GUuiffw and JVftf o/Sc0tUnd Ttchnical CoBe^ 



OUTLINES OF QUANTITATIVE ANALYSIS. 

FOR THE USE OF STUDENTS. 
With Illustrations. Fourth Edition. Crown 8vo, Cloth, 3s. 

" A practical work by a practical man . . . will further the attainment of accuracy and 
Vkt^ho^'— Journal o/Educaticn. 

"An ADM IK ABLB little volume . . . well fulfils its purpose.'*— ^cA^/mof/rr. 

"A COMPACT LABORATORY GUiDB for beginners was wanted, and the want has been wbli. 
SUPPi.iBZ>. ... A good and useful book. * — Lancet. 

** Mr. Sexton's book will be welcome to many teachers : for the processes are wn.L CHOSSn, 

the principle which tmderlies each method is always clbarly kxplained, and the '*' * 

are both simple and clbar."— ^W/. Afed Journal, 



By the same Author. 

OUTLINES OF QUALITATIVE ANALYSIS. 

FOR THE USE OF STUDENTS. 

With Illustrations. Third Edition. Crown 8vo, Cloth, 3s. 6d. 

"The work of a thoroughly practical chemist . . . and one which may be 
ini^y recommended." — British Medical J oumaL 

'^ Compiled with great care, and will supply a wnA.^—Jommal c/ Educaii oH. 

SH ELTON-BEY (W. Vincent, Foreman to the 

Imperial Ottoman Gun Factories, Constantinople) : 

THE MECHANIC'S GUIDE : A Hand-Book for Engineers and 
Artizans. With Copious Tables and Valuable Recipes for Practical Use. 
Illustrated. Second EdiiUm, Crown Svo. Qoth, 7/6. 

GsNBitAL CoKTSNTS. — Arithmetic—Geometry—Mensuration— Velocities in Boring 
and Wheel-Gearing— Wheel and Screw-Cutting— Miscellaneous Subjecu and Useul 
Kecipes— The Steam Engine — The Locomotive— Appendix : Tables for Practical Use. 

" The Mbchanic's Guidb will answer its purpose as completely as a whole series of 
elaborate text-books." — Mining Journal. 



LONDON: EXETER STREET, STRAND. 



SCIENTIFIC AND TECHNOLOGICAL WORKS. 29 

ElevsntlK Bklltaoiu Pi4«e 18s. 

Dtmy SvOt Cloth. With Numerous lUtuOrationa, reduced from 
Working Drawiiige, 

A MANUAL OF 

MARINE ENGINEERING: 

COMPRISING THE DESIGNING, CONSTRUCTION, AND 
WORKING OF MARINE MACHINERY. 

By A. E. S£ AT N, H. Inst. C. E«, H. Inst. Hech. E., 
H.Inst.N.A. 



GKNKRAL CONTKNTS- 



Part L— Prineiples of Marine 
Propulsion. 

Part II.— Principles of Steam 
Engineering. 

Part m.— Details of Marine 
Engines: Design and Cal- 



eulations for Cylinders^ 
Pistons, Valves, Expansion 
Valves, &c 

Part IV.— Propellers. 

Part v.— Boilers. 

Part VL— Miseellaneous. 



"In the three-fold oftpacity of enabling a Student to learn how to design, oonstnict^ 
and worlc a modern Marine Steam-Engine, Mr. Seaton'e Manual haa no rival as 
regards comprehensiveness of purpose and lucidity of treatment."— TitiMf. 

"The imjwrtant subject of Manne Engineering is here treated with the thorouoh- 
KESS that It requires. No department has escaped attention. . . . Gives the* 
results of mucb dose study and practical work."— fii^itaerii^^. 

" By far the best Manual in existence. . . . Gives a complete account of the 
methods of solving, with the utmost possible economy, the probleois before the Marine 
Elnfri neer."— itf Mm<s«m. 

" The Student, Draughtsman, and Engineer will find this work the most taluablk 
Handbook ot Reference on the Marine Engine now in existence."— IforJM Engin&tr, 



A POCKET-BOOK OF 

MARINE ENGINEERING RULES AND TABLES, 

TOR THE TTSB OF 

Marine Engineers, Naval Architects, Designers, Draughtsmen^ 
Superintendents, 

AND ALL ENGAGED IX THE DESIGN AND CONSTRUCTION OF 

MARINE MAGHINERT, NAVAL AND MERCANTILE. 

By A. K SEATON, M.I.C.E., M.I.Mech.E., M.I.N. A., and 

H. M. ROUNTHWAITE, M.I.Mech.E., M.I.N.A. 

With Diagrama. Pooket-Size, Leather. 

''Admirably pulfils its purpose." — Mariiu Eugineer. 

LONDON: EXETER STREET, STRAND. 



30 CHARLES QRIFFISf S OO.'S PUBLWATIOirs. 

Bj PROFESSORS J. J. THOMSON & POYNTON. 

In Large Svo. Fully Illustrated. 

A TEXT-BOOK OF PHYSICS: 

COMPRISING 

PROPERTIES or MATTER; HEAT; SOUND AND LIGHT; 
MAGNETISM AND ELEGTRICITT. 

BY 

J. H. POYNTING, J. J. THOMSON, 

SC.D.. P.E.S., AND ^-A* F-lt.S., 

{«le Fellow of Trinity College, Cambridge; Feltov of Trinity College, Cambridire: Prof. 

Profeuor of Ph7*ics< Mmou College, of Exiterimeutal Physics in the UnlYvrsity 

BlnuinKham. of Cambridge. 

Sboohd Eornoa, RmrUtd amd Enlarged. PoclM'SU*, Ltathtr^ al$»/br Qfk^ Tm, (Uth^ 111 

BOILERS, MARINE AND LAND; 

THEIR CONSTRUCTION AND STRENGTH. 

A HAin>B00K OF Rules, Ygrmxtlm, Tables, &c., relative to Matebial. 

Sgantlinqs, and Pressures, Safett Valves, Springs, 

Fittings and Mountings, &a 

for tbe TSiBC ot all Steam^^TIlBers. 
By T. W. TRAILL, M.Inst.O.E., F.E.RK, 

Engineer Siureyor-ln-Chief to the Board of Tnde. 



*«* In the New Issue the euhjeot-matter has been consideraldy extended, 
«nd Tables have been added for Pressures up to 200 lbs. per square inch. 

'*Vei7 nnllke say of the numeroas treatises on BoUen which bare precedsd It. . . . Bcally 
nsaftil. . . . Contains an Bvouioos Qdaxtitt of IstoBMATiOH arranged In a rmj coDTsalsnt 
form. . . . Those who have to design boilers wlU find that thej can settle the dimensions for anj 
CiTen pressure with almost no calculation with its aid. ... A most uuyul tolums . . . 
«uppl7lng information to be had nowhere else."— 2^ Engtmetr. 

** As a handbook of rules, formnte, tables, &c, relating to materials, scantlings, and preasarei, fhfts 
work will prore most usbvcl. The name of the Author is a suffldent foaimntee for its aoeUKy. It 
will save engineers, inspectors, and draughtsmen a rast amount of calculation.'*— ^afvrt. 

**B7 such an authority cannot but prove a welcome addition to the Uterature of the snl^eet. . . . 
We can strongly recommend it as belnig the xobt coMtiMn, eminently praetlcal.work on tha saluocL" 
^MaHme Emgtimr. 

*'To the engineer and practical boiler^maker it wQl prore ihtalvabu. Tbe tables in all pro- 
t>ability are the most exhaustive yet published. . . . Certainly deaenros a place on the shell Ib 
the drawing office of every boiler shop.'^^PracMeiil Xn g tn m r . 

LONDON: £X£T£R STRF.ET, STRAND. 



manmria and rscsifOLoenoAL works. 31 

WOBKS BY DB. ALDER WMGHT, F.B.S. 

FIXED OILS, FATS, BOTTERS, AHD WAXES: 

THEIR PREPARATIOK A3XJ> FR0FBRTIB8, 

And the Kanufactiire therefrom of Candles, Soaps, and 
Other Products. 

BY 

C. R. ALDER WRIGHT, D.Sc, F.R.S., ." 

Lecturer on Chemistry, St. Mary's Hospital School ; Examiner in "Soap** to the City 
and Guilds of London Institute. * 

In Large 8va Handsome Cloth. Wilh 144 Illustrations. 28s. 

"Will mnk as the Standard English Authority on Oils and Fats for many 
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Sboomd EDinoir. With very Xamerons lUnBtrationB. Handaome dotii, <Sa 
Also PreaenUtion Edition, Gilt and Gilt Edges, 7s. 6d. 

THE THRESHOLD OF SCIEl^CE: 

A VARIETY OF EXPERIMENTS (Over 400) 

ILLC8TRATINO 

SOME OF THE CHIEF PHYSICAL AND CHEMICAL PROPERTIES OF SURROUNDING OBJECTS^ 
AND THE EFFECTS UPON THEM OF LIGHT AND HEAL 

By C. R. alder WRIGHT, D.Sa, F.RS. 



\* To the New Edition has been added an excellent chapter on tho 
Systematic Order in which Class Experiments should be earned out for 
liaucational purposes. 

" Any one who may still have doubts regarding the value of Elementary 
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takes the trouble to understand the methods recommended by Dr. Alder 
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who wish to use the volume, not merely as a ' play-book,' but as an instrument 
for the TRAJNINO of the mental faculties."— Wo^urc. 

**Dr. Alder Wright has accomplished a task that will win for him the 
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the learner is here gently guided through the paths of science, made easy by the 
perfect knowledge of the teacher, and made flowery by the most striking and 
carious experiments. Well adapted to become the tbeastibsd fbixmd of many 
a bright and promising hA,*^— Manchester Examiner. 

LONDON : EXETER STREET, STRAND. 



3« CHARLES ORIFFIN d: CO.'S PUBLICATIONS. 

WELLS (Sidney H.jWh.Sc., Assoc. Mem. Inst CE., 

Assoc. Mem. Inst. Mech. £. ; Principal of, and Head of the Engineering 

Department in, Battersea Polytechnic Institute, late of Dulwich Collie) : 
ENGINEERING DRAWING AND DESIGN. A Practical 

Manual for Engineering Students. With very numerous Illustrations 

and Folding- Plate. In Large Crown 8vo. 
Vol. I. — Geometry, Practical, Planr, and Solid. 3s. 
Vol. II.>-Machine and Engine Drawing and Design. 4s. 6d. 

" A THOKOucHLY us«i>UL WORK, cKceedtngly well written. For the many Examples and 
<2ttestions we have nothioK but praise." —Nntitre. 

"The Examples are wxll chosbn and treated in an able manner. The Illustrations do 
GRBAT CRBOiT to the publishers.' — Scitnet and Art. 

"A CAPITAL TBXT-BOOK, arranged on an bxccclbkt systbm, calculated to give an in- 
telligent grasp of the subject, and not the mere faculty of mechanical copying. . . . Mr. 
Wells shows how to make complbtb workimc-dbawincs, discussing fully ^ch step in the 
design.** — Electrical Kexnm, 

Eleventh Annual Issue, Handsome cloth, 78. 6d. 
THE OFFICIAL YEAR-BOOK 

or THE 

Scientific and Xearned Societies ot (3reat JScitain and Jreland. 

OOMPILSD FROM OFFICIAL 80UR0E& 
Compriaing {together with other Official Information) LISTS of the 
PAPERS read during 1893 before all the LEADING SOCIETIES throughout 
the Kingdom engaged in the following Departments of Research: — 



1 1. Saence Generally : «'.#., Societies occupy* 
ing themselves with several Branches of 
Soence, or with Science and Literature 



Jointly, 
|s.Ma- 



athematics and Physics. 

1 3. Chemistry and Photographv. 

1 4. Geology, Geography, and Mineralogy. 
Is. Biology, including Microscopy and An- 

thropology. 



{ 6. Economic Science and Statistics. 

I 7. Mechanical Science and Architectnre. 

\ 8. Naval and Military Science. 

\ 9. Agriculture and Horticulture. 

} lOb Law. 

$11. Literature. 

% la. Psychology. 

I r3. Archaeology. 

f 24. Medicine. 



" The YsAR-BooK or Socibtibs is a Record which ought to be of the grertest use for 
the progress of Science.*'— ^>> Lyoit Plajtfair, Jf,R.S., K,C.B., M.P,, TasTPrvadfMt 
^tui British Assodatum, 

''It goes almost without saying that a Handbook of this subject will be in time 



one of thelnost generally useful ^o"''*" ^~fo'' thelibniry or the desk. '^ TV Times. 
*^"^T(ntS!^ocietie^r^now weii*rfpresentyr »nSi^^eaMBook of the & 
Learned Societies of Great Britain and lrclai.d."'— (Art. "Societies" in New Edition of 



_ the Scientific and 

T -. ;, —J lrclai.d.'"— TArt. "Societies" 

'"Encyclopaedia Britannica," vol. xxii.) 

Copies of the First Issue, giving an Account of the History, 
Organization, and Conditions of Membership of the various 
Societies, and forming the groundwork of the Series, may still be 
had, price 7/6. Also Copies of the following Issues, 

The YEAR-BOOK OF SOCIETIES forms a complete index to 
THE SCIENTIFIC WORK of the year in the various Departments. 
It is used as a ready Handbook in all our great Scientific 
Centres, Museums, and Libraries throughout the Kingdom, 
and has become an indispensable book of reference to every 
one engaged in Scientific Work. 

LONDON: EXETER STREET, STRAND. 



791 1004 22 J 



610*10506110 L 



i b89090 608110a 



» 




^' 



1 



•I 



■ J