116 Dr. Faraday’s Experimental Researches in Electricity. 
new trough was in all essential respects the same as that in- 
vented and described by Dr. Hare, Professor in the Univer- 
sity of Pennsylvania, to whom I have great pleasure in re- 
ferring it. 
1124. Dr. Hare has fully described his trough*. In it the 
contiguous copper plates are separated by thin veneers of 
wood, and the acid is poured on to, or off, the plates by a 
quarter revolution of an axis, to which both the trough con- 
taining the plates, and another trough to collect and hold the 
liquid, are fixed. ‘This arrangement I have found the most 
convenient of any, and have therefore adopted it. My zinc 
plates were cut from rolled metal, and when soldered to the 
copper plates had the form delineated, fig. 1. These were 
then bent over a gauge into the form fig. 2., and when packed 
in the wooden box constructed to receive them, were arranged 
as in fig. 34, little plugs of cork being used to keep the zine 
Fig. 1. 
plates from touching the copper plates, and a single or double 
thickness of cartridge paper being interposed between the con- 
tiguous surfaces of copper to prevent them from coming in 
contact. Such wes the facility afforded by this arrangement, 
that a trough of forty pairs of plates could be unpacked 
in five minutes, and repacked again in half an hour; and the 
whole series was not more than fifteen inches in length. 
1125. This trough, of forty pairs of plates three inches 
* Philosophical Magazine, 1824, vol. Ixiii. p. 241; or Silliman’s Journal, 
vol. vii. See also a previous paper by Dr. Hare, Annals of Philosophy 
[Second Series], 1821, vol. i. p. 329, [also Phil. Mag., First Series, vol. lvii. 
p- 284.] in which he speaks of the non-necessity of insulation between the 
coppers. 
+ The papers between the coppers are, for the sake of distinctness, 
omitted in the figure, 
