278 DR. DAVY’S EXPERIMENTS AND OBSERVATIONS ON THE TORPEDO. 
as females in my experiments, and the results with both have been very similar. 
Though the great breeding season appears to be in spring, females containing 
eggs variously advanced are to be met with occasionally both in summer and 
autumn, and comparing their electricity with that of barren or unimpregnated 
fish, I cannot say I can be sure of any well marked difference ; if there were 
any difference, the electricity of the former was most powerful. 
I have sometimes imagined that the age of the torpedo might modify its 
electrical effects, and that the older the fish is, the more analogous it is to 
the Leyden jar, and the younger it is, the more analogous it is to the voltaic 
battery. Many comparative trials of fishes of different ages appeared to favour 
this notion. But I soon had an opportunity of ascertaining that it is not 
universally true ; the largest torpedo I have yet obtained disproved it. This 
fish, a female Tremola, was sixteen inches and a half long, and seven inches 
and a half broad, in a languid state, having been caught several hours and 
kept in a small quantity of water ; yet a single discharge of its electricity pro- 
duced a complete revolution of the needle in the multiplier, magnetised feebly 
four bars of steel weighing seventy-five grains, and magnetised powerfully two 
small sewing-needles ; one of which acquired the power of supporting three 
times its weight of iron. Nor were the chemical effects produced by this fish 
less distinct. 
Besides the preceding, other probable causes of the difference of results I 
could wish to explain might be pointed out ; but as I have not had an oppor- 
tunity of submitting them to the proof of experiment, it would be trespassing 
on the time of the Society to bring them forward. 
Malta, September 30th, 1831 . 
