Mr . cavendish on the Torpedo. 205 
In making experiments with this inftrument, or arti- 
ficial torpedo as I fhall call it, after having kept it in wa- 
ter of about the fame faltnefs as that of the fea, till 
thoroughly loaked, I f aliened the end of one of the wires, 
that not reprefented in the drawing for example, to the 
negative licle of a large battery, and when it was fufh- 
ciently charged, touched the politive fide with the end 
of the wire w w ; by which means the battery was dif- 
charged through the torpedo : for as the wires were in- 
clofed in glafs tubes, which extended about an inch be- 
yond the end of the wood fg no electricity could pafs 
from the politive fide of the battery to the negative, ex- 
cept by flowing along the wire w w to the pewter r r, 
and thence either through the fubftance of the wood, or 
along the wet leather, to the oppolite piece of pewter, 
and thence along the other wire to the negative fide. 
When I would receive a fhock myfelf, I employed an 
aflillant to charge the battery, and when my hands were in 
the proper poll tion, to difcharge it in the above mentioned 
manner by means of the wire w w. In experiments with 
this torpedo under water, I made ufe of a wooden trough ; 
and as the llrength of the fhock may, perhaps, depend 
in fome mealure on the fize of the trough, and on the 
manner in which the torpedo lies in it, I have in fig. 4. 
given a vertical fedtion of it ; the torpedo being placed 
in the fame fituation as in the figure, abcde is the 
trough; the length bc is 19 inches; the depth ab is 
1 4 ; and the breadth is 1 3 ; confequently, as the torpedo 
is two inches thick in the thickefl part, there is about 
5t 
