272 
POPULAR SCIE^’CE REVIEW. 
Nature will not refuse to unfold some of her secrets to the new 
Davy who will best know how to use the great power placed at 
his command. 
While on the one hand this apparatus affords new means of 
research, on the other it is itself a striking example of the con- 
servation and correlation of forces, which it is the tendency of 
contemporary science to establish. The mechanical force that 
drives the coils is converted, under the eye of the observer, into 
a stream of electricity. Heat disappears in the boiler of the 
steam-engine, and Protean-like, reappears at the terminals as 
electricity, magnetism, light or heat. Here we have a strong 
argument for the dynamic theory, which would make four of 
the most important branches of general physics only different 
molecular modifications, — only different manifestations of the 
same cause. 
Viewed from a utilitarian standpoint, we should say that the 
comparatively low price of this machine — about £400* — is a close 
approximation to the production of cheap electricity. Now-a- 
days, with our strikes and our unions, every one is more or less 
of a financier, and wants a full, often an ideal, equivalent for his 
outlay. This economical recommendation is then not one of the 
least cogent, and it only remains to be shown by actual work 
that this machine may he used with decided advantage in 
various departments of the arts. Its efficiency for a few of the 
most important electro-metallurgical purposes has been tested 
in the extensive and well-known works of M. Christofle, Paris. 
The tension of the apparatus used was equal to that of two 
ordinary Bunsen cells, and the quantity to thirty-two. The 
whole weighed 9 cwt., and a one horse-power sufficed to drive 
the coils at a rate of 300 revolutions per minute. At this 
speed, it was calculated to deposit at least 20 ounces of silver 
per hour. Two series of electro-plating experiments were made 
with a view to ascertaining the relative electrolysing effects of 
the Gramme and Wilde machines, and the result was decidedly 
in favour of the former. As this is a subject of interest to the 
general scientific reader, and of especial importance to the com- 
munity at large, we shall give the details of the elaborate trials 
to which we refer.f 
Gramme Machine. 
No. 
Total deposit 
Time 
Surface of anode 
Deposit per hour 
Remarks 
oz. 
h. min. 
sq. ft. 
oz. 
rev. 
1 
209-05 
7 50 
57-62 
26-81 
300 
2 
206-67 
7 50 
67-62 
26-49 
3 
209-02 
7 50 
57-62 
26-81 
* This is the cost of the one which we have described. The demand 
will, "of course, cause a great reduction in this figure. 
t!s‘‘ Comptes Rendus Hebdomadaires des Seances de I’Academie des 
Sciences.” Dec. 2, 1872. 
