Notes. 
773 
1879.] 
Railway have been constructed by Messrs. Harding and Co., of 
Paris. The generator works at a speed of 400 revolutions a 
minute, and the inductor at half that number. The motive power 
is supplied by a Fowler 25 horse-power high-pressure compound 
engine, capable of working up to 60 horse-power, which will 
probably also be used for producing electric lights in the Metro- 
politan Meat-market and at other stations on the Metropolitan 
Railway. The cost of coal and carbons is reckoned at less than 
3d. per hour for a lamp equal in lighting-power to 600 candles, 
with an expenditure of from 1 to horse-power. The lamp 
employed is the Serrin-Lontin, and by the most recent improve- 
ment the carbons will only require renewing once in fifteen 
hours. A great advantage is that the lamps can be lighted or 
extinguished independently of each other. The experiments at 
the Aldersgate Street Station are being carried out by the 
Electric Generator and Light Company. The first evening this 
light was exhibited, Mr. Harding, of Paris, explained the pro- 
gress and capabilities of the Lontin system. “ The most inte- 
resting news on this subject is,” — remarks the “Telegraphic 
Journal,” — “the statement made by Mr. Harding, at the exhi- 
bition of the Lontin light, to the effedt that Mr. Crookes is 
engaged on some experiments with the eledtric light in vacuo , 
which promise to work an entire revolution in the prospers of 
the light. Carbons would be dispensed with, and the lamp would 
consist of a luminous globe, giving the light of (say) three 
candles. Thirty of these lamps would, it was thought, be main- 
tained by an expenditure of i£ horse-power, at a cost of less than 
a penny per hour. We have always believed that there was 
something to be made by some one, in the way of elecftric 
lighting, out of Mr. Crookes’s researches in vacuo , and we are 
gratified to hear that that eminent physicist is so near success 
himself. Mr. Edison and he are trenching upon the same ground 
with vacuo ; but whereas the former uses metal eledtro pyres, the 
latter uses none. Both are on the proper track, it seems to us, 
namely, the production of a perfectly steady light without any 
wasting of carbons or other perishable parts.” 
The Siemens electric light is now employed in the Reading 
Room of the British Museum. The main difference between the 
method adopted by Messrs. Siemens and that experimented upon 
some time ago by the Societe Generale d’Eledtricite consists in 
the use of four very powerful lamps hung high over the heads of 
the readers, instead of a number of less powerful lights at a lower 
elevation. These four lights are produced by continuous currents 
passing through wires carried over the roof of the Reading Room 
and through the top of the glass lantern in the centre of the 
dome. The eledtricity is supplied by five dynamo-eledtric 
machines placed in a shed at the back of the Museum buildings 
at about 200 yards distance, and worked from two 8-horse-power 
semi-stationary engines, supplied by Messrs. Wallis and 
