1 62 Electric Lighting. [February, 
I am unable to state the amount of this loss in trust- 
worthy figures, but should be very much surprised to learn 
that, with the best arrangements now known, more than one- 
tenth of the original energy of the coal is made practically 
available. This small illuminating residuum may, and 
doubtless will, be increased by the progress of practical 
improvement ; but, from the necessary nature of the pro- 
blem, the power available for illumination at the end of the 
series must always be but a small portion of that em- 
ployed at the beginning. 
In burning the gas derived from coal we obtain its illumi- 
nating power directly, and if we burn it properly we obtain 
nearly all. The coke residuum is also diredtly used as a 
source of heat. The chief waste of the original energy in 
the gas-works is represented by that portion of the coke 
that is burned under the retorts, and in obtaining the rela- 
tively small amount of steam-power demanded in the works. 
These are far more than paid for by the value of the liquid 
hydrocarbons and the ammonia salts, when they are properly 
utilised. 
In concluding my narrative I may add that after Mr. 
Starr’s death the patentees offered to engage me on certain 
terms to carry on his work. I declined this, simply because 
I had seen enough to convince me of the impossibility of 
any success at all corresponding to their anticipations. 
During the intervening thirty years I have abstained from 
further meddling with the eleCtric light, because all that I 
had seen then, and have heard of since, has convinced me 
that — although as a scientific achievement the eledtric light 
is a splendid success — its practical application to all pur- 
poses where cost is a matter of serious consideration is a 
complete and hopeless failure, and must of necessity con- 
tinue to be so. 
Whoever can afford to pay some shillings per hour for a 
single splendid light of solar completeness can have it 
without difficulty, but not so where the cost in pence per 
hour per burner have to be counted. 
I should add that before the publication of King’s specifi- 
cation, Mr. (now Sir William) Grove proposed the use of a 
helix or coil of platinum, made incandescent by electricity, 
as a light to be used for certain purposes. This was shown 
at the Royal Society on or about December ist, 1845., 
