Similar effects can be produced with the Voltaic Battery, but, as that instrument has already been figured, the Electric Jar has been selected. Of course any number of such jars can be connected together, and the shock will be proportionately increased in intensity.
In Nature we have several-parallels. Putting aside the obvious one of a lightning-flash, which has already been mentioned, we pass to two remarkable examples of the capability of animal structure to produce electricity, to store it up, so to speak, and discharge it at will. Both these creatures are fishes, one belonging to the Skates or Rays, and the other to the Eels.
The upper figure on the left-hand side of the illustration represents the Torpedo, sometimes called the Cramp-fish, Numb-fish, or Electric Ray. Fortunately for us, it is but seldom found on our coasts, but it is tolerably common in the warmer parts of the world.
The electric organ in this fish is double, and so large that its shape can easily be recognised even through the skin. It is made up of a vast number of discs arranged upon each other in columns like the metallic portions of the Voltaic Pile, and separated from each other by delicate membranes, which take the place of the cloth. When I mention that more than eleven hundred columns have been found in a single Torpedo, and that each column contains several hundred discs, it may be imagined that the shock which such a creature can give must be a very powerful one.
The object of this power seems to be analogous to that of the venomous serpent, i.e. to enable the creature to secure its prey by either killing it or rendering it temporarily insensible by an electric shock. As if to show that the delivery of the shock is achieved by an exertion of will, observers have noticed that just before the shock is delivered, the eyes are depressed in the head like those of a toad when swallowing a large insect.
A still more powerfully electric animal is the Electric Eel of Southern America. It sometimes attains a length of six feet, and its electric organs are four times as proportionately large as those of the torpedo.
There is no doubt as to the object of the electric power of this eel, as I have often seen it kill fish, and then eat them.
When about to deliver its shock, it curves its body towards the intended victim, stiffens itself, and with a sort of shudder the electric fluid is emitted. The fish at which it is aimed never seems to escape, but, simultaneously with the shudder on the part of the Electric Eel, turns on its back and lies motionless until it is picked up by its destroyer.
Neither the Torpedo nor the Electric Eel has unlimited stores of electricity. If irritated into delivering repeated shocks, each discharge is less powerful than its predecessor, until at last the creature is almost wholly powerless, and must rest and recruit itself before it can lay up fresh stores of the electric fluid.