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to the total cost per unit will give some idea of the effect the number of lamp hours has upon this item.

Rate per unit due to interest, &c. - The low rate per unit in No. 1 (steam plant) is owing to the greater number of hours the installation is run. For instance, if the gas engine plant No. 2 was run for the same number of lamp hours, the cost would be reduced from 2:8d. to about 95d., or a total cost per unit of 1.8d. as against 1.4d. for steam (exclusive of boiler).

Total average cost.-- In comparing the total cost per unit as herein given with the cost of energy from supply company which varies from 4 d. to 8d. per unit-it must not be forgotten that to these latter amounts there must be added an additional sum for interest and depreciation upon the wiring and lamps, also renewals and transformer and meter rent, &c., which has been included in these costs of 1.4d., 3 d. and 3:9d. respectively.

The interest &c. rate is made up of 5 per cent. interest (3 or 4 per cent. might be fairer) on first cost. ; 5 per cent. depreciation, cost of attendance, house rent, repair and renewals of lamps, &c., for portions under test.

DYNAMOS

No. 1 Plant.24-unit four-pole compound-wound · Tyne ' dynamo, belt-driven, by Messrs. Ernest Scott and Mountain, Limited; constructed to supply current for 400 16-candle-power incandescent lamps.

No. 2 Plant.24-unit two-pole compound-wound Tyne' dynamo, belt-driven ; constructed to supply current for 400 16-candle-power incandescent lamps and set of accumulator's for 100 16-candle-power lamps.

No. 3 Plant.18-unit two-pole compound-wound Tyne' dynamo, belt-driven ; constructed to supply current for 300 16-candle-power incandescent lamps.

No. 4 Plant.16-kilowatt compound-wound dynamo, beltdriven; by Messrs. Lawrence Scott and Co. Output-152 ampères, 105 volts.

In the driving of dynamos a grave error is often made in the length of belt drive ; people used to steam engine practice look to long drives as the correct thing—with the result that an excessive oscillation and wave motion is given to the belt, which seriously affects the running of the dynamo and the steadiness of the light.

The centres of engine and dynamo should not exceed 18 feet or be less than 12 feet.

INDEX

CALORIFIC value of coal gas, 197

Dowson gas, 197
Calorimeter, Junker's, 191-197
Cams, 155

types of, 156-157
Carbonic oxide, a dangerous and poison.

ous gas, 200
Carbonisation of Irish bog, 208

of sunflower seed shells, 208
Cheap fuel gas, Dowson, for driving gas
engines, 198-201

Thwaite, for driving gas en-
gines, 209-215

oil drives engines, 202
Chemical analysis, coal gas, 239
Clarke-Chapman's engine, 61-62

section, 63-64
Composition of charge--Crossley's en-

gine, 231
Connecting rods, formulæ, 88

table of sizes, marine pattern,
90

Cotter pattern, 91
lubricator, 91

two and a half times and three
times the stroke, effect on piston, 85
Cost of Dowson gas, 198

oil gas, 204

carbonising sawdust, 205
Crank shaft bearings, 104-105

table of sizes, 106

Robey pattern, 107
Crank shafts, graphic method of finding
strains of, 76–80

slab type-table of sizes, 81
bent, 81

balance type, 83
Crossley-single cylinder engine (sec-
tions), 9-10

tandem engines, 15-16
high speed engines, 18
Vertical engine (sections), 20-21
List of sizes--1895, 22

1879, 23

ABSORPTION, dynamometers to measure

the useful or brake horse-power of

engines, 170-172
Account, heat, amount of heat given to

a gas engine, 226-239
Acting, single, gas engine, 3-5

twin, gas engine, 5-6

tandem, gas engine, 6
Action in Otto engine, 3-6

in Dowson gas generator, 198–201
in Mansfield oil gas plant, 202
in Mansfield sawdust gas apparatus,
205

in Thwaite gas plant, 209-214
Actual horse power, 7
Air pump, Premier gas engine, 56-59

Diagram, 59
Air valves, 117-120
Analysis of sunflower seed shells, gas

unprepared, 209
Andrew's Stockport' gas engines, single
cylinder, 40-43

single cylinder section, 41
vertical cylinder, 42–44

tandem 400 B.H.P., 44-46
list of sizes (1895), 47
Anti-fluctuating gas bag, Crossley's, 147,
149, 150

Robey's, 150-152
Arrangement of a gas engine, 162-164
Automatic tube ignition, Robey, 138

Robey section, 139
Fielding section, 138

BALANCE of heat supplied to gas engine,

238
Barker's · Forward' gas engine, 52-54

test, 240-248

· list of sizes, 52
Beau de Rochas cycle, 2
Bunsen burner, 136

temperature of, 137
Brake, friction, dynamometer, 171

S

Cycle of operations-single cylinder en- Gas METERS-— Table of sizes, 161
gine, 3-5

Gas valve and cock, 120
twin cylinder engine, 5-6

Section, 121
tandem cylinder engine, 5-6 Governors.--- Centrifugal form, spring,
Cylinder lubricators, 152

Robey, 92–94
Crossley's, 152

Centrifugal form, Dead weight,
Robey, 154

Crossley, 96-98
Fielding, 155

- Inertia, Crossley, 96-98
- Incline, Tangyes, 99-100

Vibrating, 'Stockport,’ 101 -102
DEADLY poisonous gas--carbonic oxide,

Electric, 102
200

Arrangement of, 103
Decomposition of steam by red-hot fuel

Graphic method of determining weight
in gas generator, 198

of fly wheels, 65-70
Defects of the modern gas engine, 167–

pressure on pistons, 84-86
168

strength of shafts, 76-80
Definition-calorie, 195–196
- work, 170
of horse-powers, 7

HEAT carried off by jacket water in
Diagram averaging instrument, 183–

keeping the cylinder cool, 238
187

Heat taken up by charge during com-
Diagrams- Indicator, Clarke-Chapman,

pression, 237
64

Rejected in exhaust, 238
Diagram, indicator, scavenging method,

Horse-powers, 7
59, 166, 167

air pump. 59
Dowson gas plant, 198–201

IDLE strokes of the Otto engines, 5-6
Ignition tubes, 140-141

Indicators--Thompson, 173-174
ELECTRIC governor-Robey, 102-104

(Section), 175
ignition-Clarke-Chapman, 63-64

Crosby (Section), 176-177

Tabor, 177-178
lighting—(private), Mr. Hanning,

(Section), 179-180
248–255
Exhaust silencing chambers, 157

Wayne, 180-182
ordinary pattern, 158
Justice pattern, 159

JACKET-WATER, heat list. Measurement
Robey & Tangye pattern, 160_

of, 238
161

Joints--Combustion chambers, 9, 20, 25,
valves, 118, 156

35, 41
auxiliary valve, 39

- Exhaust valve boxes, 10, 25, 35,
41

Junkers' Calorimeter, 191-197
Fat melted and used to make gas to

drive engines, 202
Fielding & Platt ‘Fielding'single LARGE power engines, 167-168

cylinder horizontal engine, 100 B.H.P. | Life, average, of ignition tubes, 140-141
49

Lubricators for connecting rod, 91-92
Fielding & Platt •Fielding' single for cylinder, 152-155

cylinder vertical engine, 100 B.H.P.,
50
List of sizes, 1895, 51

MANSFIELD oil

gas,

202
Fly wheels, object, 65

Arrangement of, 203
Graphic method of determining Sawdust gas apparatus, 205
weight of, 65-66

Arrangement of, 206–207
Various methods of keying wheels to Measuring area of indicator diagram
shafts, 72-73

by planimeter, 183
Keys, 74

- power of friction brake, 170
Lanchester's formulæ, 75

Mechanical efficiency of a ga engine,
Friction of gas engines, 168-169

238

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