34 
POPULAR SCIENCE REVIEW. 
to them will be at the rate of about lJcZ. per light per hour. 
Mr. Shoolbred stated that the Societe place their expenses at 
l*06f. (or just lOcL) per light per hour, which, however, they 
hope shortly to reduce by one-half.* A series of careful photo- 
metric experiments carried out by the municipal authorities 
with the Jablochkoff lights, above referred to, showed each 
naked light to possess a maximum intensity of 300 candles. 
With the glass globe this was reduced to 180 candles, showing 
a loss of 40 per cent., while during the darker periods through 
which the lights passed the light was as low as 90 candles. 
The foregoing were the only authenticated particulars which 
Mr. Shoolbred could obtain as regards the working of the 
various systems of electric lighting. In conclusion he re- 
ferred to the Kapieff light at the 4 Times’ office, which, he ob- 
served, worked fairly and with regularity, which could not be 
said of all others, and it might therefore be entitled to take 
rank as an established application of electric illumination. 
46 The practical illustration,” says Mr. Siemens in an excellent 
letter to the 44 Times,” 44 of the power of the electrical conductor 
serves to show the possibility of application upon a large scale 
such as I have ventured to suggest. A true comparison between 
the cost of the electric current and its rival, gas, cannot be 
instituted until central motor stations are established in popu- 
lous districts, where steam power may be produced at the 
cheap rate of two and a half pounds of coal per horse-power per 
hour, and whence radial conductors may supply the neighbour- 
* Mr. Stavton’s very sensible report to the Vestry of the Parish of Chelsea 
points out that a 16-horse power engine in Paris supplies 16 lamps, exactly one- 
horse power per lamp ; that the candle itself costs 7 \d. } and burns an hour and 
a half, being automatically replaced without visible interruption. The intensity 
of the light is 700 candles without, and one- third less with the globes ; the or- 
dinary London street lamp only equalling 12 to 1 5 candles. Each light, which 
only burns from dusk to midnight, costs lfr. 45c., i.e. 1 s. 2\d. per hour, the 
general cost being four times that of gas, but that a greater amount of light 
is obtained. Paris, it appears from the same report, is already much better 
lighted than London. To adopt the electric light to Sloane Street, which is 
11,000 yards long and 20 wide, would require two stations with 16-horse 
power engines, and other machinery costing 3,200/. The cost of main- 
tenance of candles, &c., would be 16 shillings per hour for an average of 
3,250 hours per annum. The gas lamp now costs 8%d. per hour. To light 
the Chelsea Embankment would require an outlay of 4,800/., and an hourly 
cost of 1/. 4s. 0 d. The present cost is 2s. ] $d. per hour. Sloane Street, how- 
ever, would be 31 times brighter than at present, which, by the way, it 
might well be with advantage to wayfarers. He shows that the conveyance 
of electricity involves enormous loss ; that a little is saved by instantaneous 
lighting and extinguishing,thatthelight is safe for horses, powerful, innocuous, 
free from heat, but on the whole not suitable for street lighting, though it is 
suitable for large spaces such as Trafalgar and Parliament Squares. We en- 
tiiely agree with the worthy engineer. 
