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General Library System
University of Wisconsin-Madison
728 State Street
Madison, Wl 53706-1494
U.S.A.
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.
GRIFFIN'S POCKET-BOOKS.
NEW BOOK by Mr. SEATON.
MARINE ENGINEERING RULES AND TABLES (A Pocket-Book
oO- Por the use of Marine Engineers, Naval Architects, Designers, Draughtsmen,
Superintendents, and all engaged in the design and construction of Marine Machinery,
Naval and MercantUe. By A. B. Sbaton, M.Inst.C.E., and H. M. Bounthwaiti,
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
strength. A Handbook of Bules, FormuIoB, Tables, &c.. relative to Material, Scant-
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
MuNRO, C.E., and Prof. Jamieson, M.InstC.E., F.B.S.E. Ninth Edition. Pocket
Size, Leather, Ss. 6d.
*' Wokdbbvdllt Pbbf bct."— JSZeetrieian.
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of Electrical, Civil, Marine, and Borough Engineers, Local Authorities, Architects,
BaUway Contractors, <ftc., <fec. Edited by H. J. Dowsing, Member of the Institution
of Electrical Engineers. For Office use, 88. 6d. Also for the Pocket, 8s. Qd.
"AuBXCKPTioNALLT oooD WORK or bbfrbbvcb. . . . Besides the Prioe-List proper, esch
section is prefaced by valuablb information."— £{ec<riea2 Engineer.
"The Electrical Frlce-Bouk rbxovbs all htstbbt about the cost of electrical power. By its
aid the bspbhsb that will be entailed by utilising electricity on a large or small scale can be dis-
covered. . . . Contains that sort of luformation which is most often required in an office when
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.
III.-THE STEAM ENGINE AND OTHER PRIME MOVERS. Thirteenth Edition. 12b. 6d.
IV.— A MANUAL OF MACHINERY AND MILLWORK. Thirteenth Edition. 12s. ed.
V.-USEFUL RULES FOR ENGINBEBS. ARCHITECTS, BUILDERS, ELB0TRIGIAN8,
Ac. Seventh Edition, los. 6d.
VI. -A MECHANICAL TEXT-BOOK: A Simple Introduction to the Study of Mechanics.
Fourth Edition. Os.
VII.— PROFESSOR RANKINE'S MISCELLANEOUS SCIENTIFIC PAPERS. With Memoir b/
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-
.Above
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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
Corporation of London under the Petroleum Acts,
Ac., Ac.
ASSISTED BT
; GEO. T. HOLLOWAY, RLC,
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COLE (Prof.), PracticaraeoloRy, . . 7
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Oils and Fats, Soaps and Candles, . 31
YEAR-BOOK of SeientillcSocielies, . 3S
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THE DESIGN OF STRUCTURES:
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9fNat, History,
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BT
W. SANTO CRIMP, M.INST.C.E., F.G.S.,
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Introduction.
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Houriy and Daily Flow of Sewage.
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■ 'om the Sewage
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The Pr^axation of Land for Sewage Di*>
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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
Boiler Construction,
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,
Assay, and Analysis of White Pigments— Red Pigments— Yellow and Orange
Pigments — Green Pigments — Blue Pigments — Brown Pigments — Black Pigments
—Lakes — Colour and Paint Machinery— Paint Vehicles (Oils, Turpentine, &c.,
Soa, )— Driers— Vasnishes.
** Thb useful book most successfully combines Theory and Practice . . . wHI prom
MOOT VALUABLS. We feel bound to recommend it to all engaged m the arts concerned."—
Ckemncal News.
** A praetieai manual in every respect. The directions are concise, clearly intelligible,
and BXCBBDiNGLY iNSTRi'CTivs. The section on Varnishes the most reasonable we have
met with." — Chemist and Druegist.
" A work that is both useful and neoessai^. from the pen of a writer experienced in bom
ways than one with the very wide subject with which he deals. Vutv valuablb infonaa-
tion is given."— /*iW»fArr and Deccraier,
*' A thoroughly practical book, . . . constituting, we believe, the only Boclisli
work that satisfactorily treats of the manu&cture of oils, colours, and pigmenU."— CA^jwam/
Trades' yenrmsL
" Throiuchout the wodc aie scattered hinu which are inyaluablb to the
nadet^^Jnt/entien,
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.
2. MAGNETISM AND ELECTRICITY (An Advanced Text-
Book on). Specially arranged for Advanced and ** Honours " Students.
8. APPLIED MECHANICS (An Advanced Text-Book on).
Specially arranged for Advanced and " Honours" Students.
PROFESSOR JAHIESOM'S INTRODUCTORT llANUALS.
In Crown Svo, Cloth, With very numerous Illlustratiotis and
Examination Papers.
1. STEAM AND THE STEAM-ENGINE (Elementary Text-
Book on). Specially arranged for First-Year Students. Third-
Edition. 3/6.
** Quite the right sort op book."— f «</j»*irr,
" Should be in the hands of bvkry engineering apprentice." — Practical Enginetr,
2. MAGNETISM AND ELECTRICITY (Elementary Text-
Book on). Specially arranged for First-Year Students. Third
Edition. 3/6.
" A capital text-book . . . The diajo^ms are an important feature."— .SVA<9<7//NAr/^r.
"A THOROUGHLY TRUSTWORTHY Text-book. . . . Arrangement as good as well
can be. . . . Diagrams are also excellent. . . . The subject throughout treated as axr
essentially practical one, and very dear instructions given." — Nature.
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.
** The MOST VALUABLK and usktul wohk on Dyeing that has yet appeared In the English
laagoage . . . likely to bo tbe Stjuiiubo work or BaFSBncB for yean to oomoT—
TixtlU Mercury.
In Two Large 8vo Volumes, 920
pp., with a SUPPLEMENTARY
Volume, containing Specimens
of Dyed Fabrics. Handsome
Cloth, 45s.
MANUAL OF DYEING:
fOR THE USE OF PRACTICAL DYERS, MANUFACTURERS, STUDENTS,
AND ALL INTERESTED IN THE ART OF DYEING.
BY
E. KNECHT, Ph.D., F.LC, CHR. RAWSON, F.LC., F.C.S.,
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-
Water — Washing and Bleaching — Acids, Alkalies, Mordants — Natural
Colouring Matters — Artificial Organic Colouring Matters — Mineral Coloun
— Machinery used in Dyeing — Tinctorial Properties of Colouring Matters —
Analysis and Valuation of Materials used in Dyeing, &c., &c
*' This MOST VALUABLE WOBK . . . wiU be widely appreciated."— CK«ml6al iTcwf.
** This authoritatiTe and ezhaastlTe work . . . the most complbtx we have yet seen
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^' The MOBT mcHAUsnyz and complktk work on the snbject extant "—TfartOe Reetrder.
" The diatingaiahed authors have placed in the hands of those daily engaged in the dye-
house or laboratory a work of bxtkkmb valdr %nd undoubtbd uriLrrr . . . appeals
quickly to the technologist, colour chemist, dyer, and more particularly to the rising dyer
of the present generation. A book which U la rafirsshiag to meet with.^~il«iMHeaA TtxtiU
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.
manuals hitherto published on Electro-Metallurgy."— AVcc^'ca/ Review,
" 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
APPLICATION of electrolytic processes."— i^aitire.
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.
This work, written chiefly to meet the wants of Mechanics, Engine-
keepers, and Boiler-attendants, also contains information of the first import-
ance to every user of Steam-power. It is a pb actical work written for prac-
tical men, the language and rules being throughout of the simplest nature.
General Contents. — Explosions caused by Overheating of Plates : (a)
Shortness of Water: (6) Deposit — Explosions caused by Defective and
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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OJV THE BASIS OF PHILLIPS.
VI
HARRY GOVIER SEELEY, F.R.S.,
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VUtb yrontldpiece in CbcomooXitbOdtapbSt anb Jlluatrationa*
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Demy 8vo, Handsome doth, 34^.
StratigrapMcal Geology & Falsontology,
OJf THE BASIS OF PHILLIPS. ,
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OF mMrmaMHcm.**-'Athememm,
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32 CHARLES GRiniN S CO^B PUBLICATIONS.
Third Edition, if«mMef hy Mr. H, Bauerman^ F.O,S.
ELEMENTS OP METALLURGYs
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By J. ARTHUR PHILLIPS, M.Inst. C.E.,F.O.S., F.G.S., &c..
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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-
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In order to render the work complete for the purposes of the Shipbuilder, whether at
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STANDARD WORKS OF REFERENCE
FOR
Metallurgists, Mine-Ownevs, Assayen, Mnvfticlnrers,
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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,
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1. nrraiODUCTIOM* to the STUDY of VSniAl^TTBLOtY.
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4. IBON and STEEL (The MetaUurgy of). By Thos.
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6. METALLUBQICAL MAGHINEBY: the Application of
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e. AIiLOYS. By the Editor.
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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 —
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Bridges — Dock-gate Machinery — Hydraulic Brake — Hydraulic Power applied
to Gunnery — Centrifugal Pumps — Water Wheels — Turbines— Jet Propulsion —
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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.
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*«* The Sxcovo Editiov of the above Important wortc has been thoroughly revised and
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Demy 8yo^ with Numerous Illustrations, 9/.
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By A. E. S£ AT N, H. Inst. C. E«, H. Inst. Hech. E.,
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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.
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MARINE MAGHINERT, NAVAL AND MERCANTILE.
By A. K SEATON, M.I.C.E., M.I.Mech.E., M.I.N. A., and
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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
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'"Encyclopaedia Britannica," vol. xxii.)
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