6 Prof. Loomis on Electricity of Zine buried in the earth. 
copper plate of three and one-third square inches, counting both 
sides, the surface of the plate must be increased fourteen fold; 
and in order to increase the current fourfold, the surface of the 
plate must be increased four hundred and twenty fold. In order 
to double the current again would probably require a copper plate 
more than sixteen feet squa 
The following camadiiente were performed to determine how 
far the intensity of the current could be increased by multiplying — 
the number of galvanic elements. 3 
30. I buried a plate of zine six inches square in the — 
earth at a distance of twelve feet from the well used in the pre-_ 
ceding experiments. The depth to the surface of the water in- 
the well was also twelve feet. A plate of copper six inches — 
square being attached to a wire and dropped into the well, the — 
galvanometer settled at 45°. 
Exp. 31. [ then buried a second copper plate of the same_ 
dimensions in the earth at a distance of one inch from the first 
zine plate, and connected it by a wire with a second zinc plate 
which was immersed in the well by the side of the copper plate 
and separated from it to the distance of half an inch by interposed 
ey ‘The galvanometer settled at 58°. The tangents of 45° 
Or are in the ratio of ten to sixteen. In this ratio the in-— 
‘ Hensity of the current had been increased by the addition of a— 
second pair of plates. ‘ 
Exp. 32. I removed the second copper plate to the distance — 
of fits inches from the zine plate which was buried in the earth. — 
The galvanometer settled at 50°. _ I then interposed between the — 
copper and zinc a third pair of plates of the same dimensions, — 
when the galvanometer settled. at 58°. This experiment did not 
afford much encouragement for inereasing the number of ee : 
the soil was only eight inches deep, a flat s 
With one zinc plate in the earth and one cop 
the galvanometer settled at 26°. 
Exp. 34, With a copper plate i in the earth” 
from the zinc, and a pair of plates in the well, 
31, the galvanometer settled at 44°. The tanger 
44° are almost exactly in the ratio of one to tw 
sity of the current was therefore doubled by the 
second pair of plates. 
Exp. 35. I removed the second copper plate to the: 
twelve inches from the zinc which was buried in~ 
The galvanometer settled at 284°. I placed the copper pl 
inches from the zinc, when the galvanometer settled at 30° 
placed the copper plate five inches from the zinc when the 
vanometer settled at 33°. I then interposed a third pair of pl 
