170 
ARTIFICIAL ILLUMINATION. 
leum lamp would cost 38s., and if we were to decide to get the same 
light in electric lamps, supplied by current taken from the mains at 6d. 
per unit, it would cost us annually 204s., or eight times as much as the 
same light upon the “ Welsbach”’ system. 
And now we come to the last table which I propose to show 
It is a comparative estimate of the cost of lighting by electricity 
(4.) 
you. 
and gas on the assumption that the electric current is generated by 
our own gas engines. 
CoMPARATIVE Estimate or Cost or Liguting py HLEcTRIcrty AND GAS. 
30 Lamps. 300 Lamps. 
(Gas Engine, 2-H.P. Nominal | £80) £300) 
| | 
| Dynamo, 50 Volts, 40 Am- | | , 
|e akpercs Aree DEVS Ie apes el 160 
Outlay | : | 
+ Lamps (16 candle) Switches, £205 Pp £1145 
On ETO, [SRemVELVCSHCC mee seamen. Meee mee 0 | 150 | 
| Accumulators 60 | 460 | 
Execrricity. | Fitting 10 | 15) 
(Renewal of Lamps, 80 at | £6) £60 } 
| | ts. Gel. | | 
Depreciation—10°/, on £200 | 20 | 10 | 
Annual . | 
Expenditure J Evol 20 | 65 ly + £367 
yap a 
(1500 hours.) | Gas and Oil for Engines 12 120 
| Interest on Plant, 4°/, on | | 
L £175 og ester 1) 39) 
(Good Ordinary Burners, 
|. - giving 23 candle power perc. ft. | 
of gas 
| g 
| £40 £400 
| 288,000 cubic feet at 2/6 per 1000 | 
Renae | Depreciation, Repairs, Interest, | 
Gas. xpen- | a J 
EAT, | Welsbach Incandescent, 7 
| giving 12 candle power per c. ft. | 
eliza: + £14 £140 
| 60,000 cubic feet of gas, | 
| Depreciation, Renewals, &.  _J 
Note.—If Electricity is supplied from public mains at 6d. 
per Board of Trade unit, the annual cost, at 4 Watts per > £78 and £780 
candle power, including renewal of lamps, will be... . 
