1816.] during the Year 1815. li 
coating of shell lac, and incloséd in a hollow brass cylinder. ‘Two 
of these piles are placed at the distance of four or five inches from 
each other; and between them is suspended a light metallic needle 
on a pivot, which is attracted alternately to the one pile and the 
other, so that it constantly moves between them like a pendulum. 
Attempts have been made to make this electric pendulum the 
moving power of a clock or watch ; and these attempts have to a 
certain degree succeeded. Dr. lager, of Stuttgardt, has made a 
number of experiments upon this pile, both as modified by De Luc 
and by Zamboni. But on looking them over in a cursory manner, 
I did not perceive any additions of much importance to our previous 
knowledge. 
5. Dr. Wollaston’s ‘elementary galvanic battery, described in a 
late number of the Annals of Philosophy, constitutes a discovery of 
considerable importance. It demonstrates the vast quantity of elec- 
tricity which is disengaged during the chemical action of acids on 
metals, and thereby serves to throw much additional light upon the 
stil] obscure theory of galvanism. 
G. I shall add here the result of Mr. Children’s experiments with 
his immense galvanic battery, though they are mostly chemical ; 
because I could not place them under the department of chemistry, 
without dividing them so much as to destroy their interest. 
The battery consisted of 20 pairs (or rather 20 triads) of copper 
and zinc plates, each six feet long by two feet eight inches broad. 
and presenting 32 feet of surface. ‘They were connected together 
by leaden straps. Wooden troughs filled with water containing a 
mixture of sulphuric and nitric acids, and each water-tight, were 
prepared for each triad, and the metals were so suspended and 
counterpoised that they could be elevated and let down at pleasure. 
There were two copper plates in each cell, and the zinc plate was 
interposed between them. The order in which metallic wires con- 
necting the two poles of this battery became red-hot was as follows : 
Platinum. Copper. Zine. 
Iron. Gold. Silver. 
Tin and lead melting before. they became red-hot their place 
could not be determined. Mr. Children conceives that the metals 
conveying electricity become red-hot inversely as their conducting 
power. According to this supposition, the conducting power of 
these metals for electricity is in the following order :— 
Silver. j Gold. 2 Tron. 
Zine. Copper. 5 Platinum. 
The power of this immense battery may be estimated by the 
following experiments :— 
Five feet six inches of platinum wire 0°11 inch in diameter were 
heated red-hot throughout visible in day-light. 
Eight fect six inches of a platinum wire 0-44 inch diameter were 
heated red. 
