’ 
March 23, 1882} 
oxide to pure lead, and the lead peroxide, on the other side, to 
an even more oxidised -alt. Ov. using the cell to produce an 
external useful current, the pure spongy lead becomes again 
slightly more oxidised, and the peroxide slightly less oxidised. 
In fact, there is a small quantity of oxygen which travels back- 
wards and forwards a the cell is charged and discharged. 
Now, does such a cell store electricity? No! emphatically 
no! When charging it, just as much electricity passes out as 
passes in, and, when discharging it, ju:t as much electricity 
pas:es in as passes out. 
Imagine a stream of water was turning a water-wheel, and the 
water-wheel was employed to raise corn up into a granary, the 
arrangement might be called one for storing corn, but certainly 
not one for storing water. So a secondary battery does not 
store electricity, but electric energy. 
The pith, then, of Faure’s discovery is the mechanical placing 
of a salt of lead on the leaden plates the pre-ence of which layer 
of lead salt enables spongy lead to be produced in a few days, 
instead of requiring many mouths, when the spongy lead is 
electrically formed out of the lead plates themselves by the long 
passage of electric currents. 
The next point to consider is: (1) the storing capacity of such 
an accumulator ; (2) its efficiency ; (3) its durability, Now I 
am, I am glad to say, able to give you more than hearsay 
evidence on this point, since Prof. Verry and myself have been 
engaged on rather a long series of experiments on this subject. 
I may mention that we were both rather sceptical abeut the 
merits of the Faure accumulator before commencing this investi- 
gation, since we feared that the reports of its excellent action 
were almost too good to be true. Our doubts, however, gradually 
dispelled themselves as the investigation proceeded, and we now 
are able to add our tribute to its practical value. 
Let us take a single example of the storing capacity. A 
certain cell, containing 81 lbs. of lead and red lead, was charged 
and then discharged, the discharge lasting eighteen hours—six 
hours on three successive days ; and it was found that the total 
discharge represented an amount of electric energy exceeding 
1,440,000 foot Ibs, of work. This is equivalent to 1 horse-power 
for three-quarters of an hour, or 18,000 foot Ibs. of work stored 
per lb. weight of lead and red lead. The large curve shows 
graphically the results of the discharge. Horizontal distances 
represent time in minutes, and vertical di-tances foot lbs. per 
minute of energy given out by the cell, and the area of the 
curve therefore the total work yiven out. On the second day we 
made it give out energy more rapidly than the first, and on the 
third more rapidly than on the second, this being done of course 
by diminishing the total re-istance in circuit. During the last day 
we were discharging with a current of about 25 ampéres. But 
in connection with the storing power, there is a very curious 
phenomenon to which I think not nearly sufficient attention has 
been directed, and that is the resuscitating power of a Faure’s 
cell. When a cell has been apparently completely discharged, 
and is left for a few hours by itself, it appears to have obtained 
anew charge. For example after the eighteen hours discharge 
just referred to, although there apparently was no electric energy 
left in the cell at the end, it was found that after a few hours’ 
insulation, the accumulator could give a current of over 50 
ampéres, and produce therefore bright flashes of fire. The 
phenomenon is wonderfully like the invigorating action of sleep, 
In one case, during our experiments of an extremely rapid and 
powerful discharge, we found that in subsequent discharges 
after rest, the cell gave out three times as much energy as it did 
in the first discharge. The neglect of considering this resusci- 
tating power has doubtless misled many people who have possibly 
discharged a Faure’s cell very rapidly, into under-estimating its 
storing capacity. 
Secondly, as regards efficiency. The efficiency of an electric 
accumulator—that is, the ratio of the work put into it to the 
work given out—depeids on the speed with which it is charged, 
and the speed with which it is di-charged. If charged or dis- 
charged too quickly, a certain amount of energy will be wasted, 
heating the cell itself; since, whenever a current passes through 
a body, some heat is developed, and the greater the current, the 
greater the heat, the latter, indeed, increasing much more rapidly 
than the current. Now, it is possible, in a way I will not at the 
moment trouble you by explaining, to distinguish between the 
work given to the cell to produce chemical decomposition and 
the work wasted by too burried charging. Similarly, in discharg- 
ing, it is also possible to find out how much of the electric energy 
stored up in the cell is wasted in heating it by too hurried discharg- 
2 >) eee as 
‘3 3 5 - essa me eas 
NATURE 
497 
ing. Allowing for such unnecessary waste, experiment shows 
that, for a million foot-pounds of stored energy discharged witha 
mean current of 17 amperes, the loss in charging and discharging 
combined need not exceed 18 per cent. ; indeed, in some cases 
for very slow discharges, we have found it not to exceed 10 per 
cent. I do not, of course, mean by this, as some ; eople have 
mistakenly imayined from the published numbers of Prof, Perry 
and myself, that a current of only 17 ampéres can be obtained 
by discharging a single cell; since, of course, far greater dis- 
charge-currents can be produced if the external resistance be 
low; indeed, I shall show you a constant discharye of about 
79 amperes presently. In speaking of the nuuber 17, T merely 
mean to say that was the average current when the experiments 
on the efficiency above referred to were made, 
As to deterioration, two months constant charging and dis- 
charging of the two test-cells showed no signs of deterioration. 
T have said that a cell containing 81 Ibs, of lead and red lead 
stored 1,440,000 foot-pounds of work. Now, consider what 
that means, It represents all the energy required to be expended 
to pull a tramear containing forty-six passengers over two miles, 
after allowing for considerable waste of power in the electrical 
arrangements. The electromotor and gearing need not weigh, as 
I told you, more than about 200 Ibs., to produce about two horse- 
power. Wehave, therefore, this wonderful conclusion, that about 
300 Ibs. dead weight contains all the energy and all the machinery 
necessary for over two miles’ run of a tramcar with forty-six 
passengers, Now, is this result actually obtained at present in 
the tramcar running at Leytonstone, and which is propelled by 
Faure’s accumulators? No, and why? Partly because the 
electro-motor has not been made to suit the accumulators, nor 
the accuwulators the electro-motor, nor is the gearing adapted 
to either, 
The cells, as at present made, would not give off their energy 
quickly enough; hence a greater number are employed, but 
which, consequently, require to be charged much less frequently 
than would otherwise be necessary. Indeed, in a ton of the 
cells as at present constructed, there is about fifty miles’ run of 
a tramcar containing forty-six passengers. 
But, in spite of the temporary character of this arrangement, 
the total weight of the Faure cells, dynamo and gearing com- 
bined, used at Leytonstone, is only 14 tons, or one-third of the 
weight of a detached steam or compressed air-engine commonly 
used for tramcars, 
Spacious as is the Lecture Theatre of the London Institution, 
it is unfortunately not large enough to admit a tramcar, I have 
therefore done the next best thing to prove to you that the 
Faure accumulators really contain a vast store of available 
energy. We have here a circular saw which is now cutting wood 
over an inch in thickness, As you see, the circular saw is driven 
by that Gramme electro-motor, and the electro-motor itself is 
fed by the energy stored up in these accumulators, and which 
was put into them by a dynamo machine yesterday, on the other 
side of London, 
When the Faure’s accumulator was first invented, there were 
Various suggestions of electricity being delivered at houses every 
morning like milk in cans, and the exaggeration of this idea no 
doubt did something to prejudice the cells in the eyes of the public. 
The reason why milk is delivered in cans and brought by carts 
is simply because the total quantity required is so extremely 
small. If milk were required to be consumed in large quantities 
like water is, we should have it sent through pipes, and not by 
cans. The main use of the accumulators will be as stationary 
reservoirs corresponding with cisterns for water or gasometers 
for gas. But in certain cases where the accumulators can be 
used to propel a cart, as in the case of tramears, not the cart 
employed solely to carry the accumulators, then there is not the 
same objection to their being moved about, seeing that the total 
weight necessary is small compared with that necessary for a 
steam-engine or a compressed-air engine for tram lines to develop 
the same horse-power. 
Again, just as ordinary electro-motors are not made to dis- 
charge a Faure’s cell rapidly, so ordinary electric lamps are 
unsuited for this purpose ; and, therefore, although there is 
enough energy, in a 100 Ibs, dead weight of Faure accumulator, 
to give a light of 1500 candles for thirty minutes, an ordinary 
electric Jamp cannot be illuminated at all by a single cell. Mr. 
Edison, however, has been turning his attention to this subject, 
and here is the result of his handiwork, which arrived last night 
from America, and which is, therefore, shown for the first time 
in England this evening. This incandescent lamp, as you see, 
