SCIENTIFIC SUMMARY. 
283 
ordinary chain ecraseur, as it must have heen had the Faure cell not been 
available, because, in the circumstances, the surgical electrician, with his 
paraphernalia of voltaic battery to be set up beforehand, would not have heen 
practically admissible. 
‘The largest useful application waiting just now for the Faure battery — 
and it is to he hoped that the very minimum of time will he allowed to pass 
till the battery is supplied for this application — is to do for the electric light 
what a water cistern in a house does for an inconstant water supply. A 
little battery of seven of the boxes described by your correspondent suffices 
to give incandescence in Swan or Edison lights to the extent of one hundred 
candles for six hours, without any perceptible diminution of brilliancy. 
Thus, instead of needing a gas-engine or steam-engine to he kept at work as 
long as the light is wanted, with the liability of the light failing at any 
moment through the slipping of a belt — an accident of too frequent occur- 
rence — or any other breakdown or stoppage of the machinery, and instead of 
the wasteful inactivity during the hours of day or night when the light is 
not required, the engine may he kept going all day and stopped at night, or 
it may be kept going day and night, which will undoubtedly he the most 
economical plan when the electric light comes into general enough use. The 
Faure accumulator, always kept charged from the engine by the house-supply 
wire, with a proper automatic stop to check the supply when the accumu- 
lator is full, will he always ready at any hour of the day or night to give 
whatever light is required. Precisely the same advantages in respect of force 
will be gained by the accumulator when the electric town supply is, as it 
surely will he before many years pass, regularly used for turning lathes and 
other machinery in workshops and sewing machines in private houses. 
I Another very important application of the accumulator is for the elec- 
tric lighting of steamships. A dynamo-electric machine of very moderate 
magnitude and expense, driven by a belt from a drum on the main shaft, 
working through the twenty-four hours, will keep a Faure accumulator full, 
and thus, notwithstanding irregularities of the speed of the engine at sea or 
occasional stoppages, the supply of electricity will always be ready to feed 
Swan or Edison lamps in the engine-rooms and cabins, or arc lights for mast- 
head and red and green side lamps, with more certainity and regularity than 
have yet been achieved in the gas supply for any house on terra firma. 
I I must apologize for trespassing so largely on your space. My apology 
is that the subject is exciting great interest among the public, and that even 
so slight an instalment of information and suggestions as I venture to offer in 
this letter may be acceptable to some of your readers. 
‘ I remain, your obedient servant, 
‘ William Thomson. 
* The University , Glasgow , June 6.’ 
‘Sir, — Although agreeing with every word of Sir William Thomson’s 
letter in the Times of to-day, and entirely sympathizing with his enthusiasm 
as regards the marvellous box of electricity, still I feel that it would have 
been desirable if, in pointing out the importance of this new discovery, Sir 
William Thomson had guarded against a very probable misconstruction of 
the purport of his letter. 
