of the two fluids, being sufficient to set in active vibration the interstitial ethereal elements of the platinum, and thus produce the phenomena of heat and light you are now witnessing. I now allow the discharge or union to take place between these fragments of carbon; the intense evolution of light well attests the violence with which the ether is made to vibrate. Now I will compel the two elements to traverse this water before they unite so powerful is the influence of these wondrous agents, that chemical affinity is annihilated, the water is resolved into its elements, and torrents of oxygen and hydrogen are evolved. Lastly, I have before me two bars of iron surrounded by wire; these are at present merely inert metal, possessing nothing peculiar, save in figure. Let us now compel the two fluids to traverse the wire round these bars before they unite. In an instant the bars assume new properties, becoming magnets of enormous power, rapidly and violently attracting the iron ball suspended over them, and seizing, with almost uncontrollable power, the bar of iron I now present to them.

I said that change of temperature is sufficient to disturb the electric equilibrium of bodies. This is invariably true, and a single illustration will, I hope, be regarded as sufficient.

On the table before me is a large magnetic needle suspended on a pivot; some coils of insu

lated copper wire pass above and below the bar, the apparatus being, indeed, the well-known galvanometer (fig. 4.*). Here is a bar of the metal bismuth; and I will twist the terminations of the wire coil round the ends of the bar. The needle remains at rest; no disturbance of electricity occurs. But observe what occurs the instant the flame of a spirit-lamp comes in contact with one end of the bismuth. The magnetic needle, large and heavy as it is, begins to move, and soon traverses an arc of thirty degrees. By the propagation of the calorific vibrations through the bismuth, its electric equilibrium is disturbed, and a current of the posi tive and negative fluids traverses the wire coil, and produce their well-known effects upon the magnet.

I trust I have not trespassed too long upon your patience in thus bringing before you facts

* Fig. 4. A, a galvanometer furnished with a coil of thirty folds of thick insulated copper wire, between which is suspended the magnetic needle, n s. The bar of bismuth is connected, by copper wire twisted round its two extremities, with the screws of the galvanometer. Heat is applied to one end of the bar by the spirit lamp, C.

with which I am sure all present are familiar. I felt, however, that your time might not be uselessly spent in thus recalling to mind the wellrecognised effects of electricity, before passing to its more occult phenomena.

All are ready to admit the presence of electricity in inanimate matter, and, perhaps, to extend it to those animals which are endowed with the mysterious property of benumbing the hand which grasps them; still, all may not be so willing to accord these attributes to man, and to regard him as endowed with a large accumulation of electric fluid.

But nothing is easier than to elicit ample evidence of this truth; and I can readily produce the phenomena of divergence by my own electricity. For this purpose I will stand upon a stool Interio with glass non-conducting legs, and thus, in an "electrical sense, am no longer an inhabitant of man earth, being insulated from its electricity. Placing a finger of one hand in contact with the cap of the electrometer before me, I with the other will briskly draw a non-conducting comb of tortoiseshell through my hair, the comb being connected with the earth by a wire. Immediately the gold leaves diverge; indeed, I have evolved so much electricity, that one of the leaves has become torn by the violence of its divergence from its com-panion.

In inanimate nature, we find electricity playing a part so important, that it could scarcely be dispensed with. Many of the most important of the chemical phenomena of the universe would disappear in its absence. Little of the intensity of chemical affinity, as it is termed, few of the marvellous phenomena so profusely scattered for our inspection and use in the great mineral districts of this and other countries would be developed, -were it not for the presiding influence of the wonderful thing we call electricity. There can, indeed, be little doubt of its being one of the most energetic and most generally diffused means employed by the All-wise Creator for the production of most of the phenomena of the material world.

If, then, this agent exists so freely diffused in the animal, can we doubt its having some important function to perform? In the torpedo and silurus its influence is obvious, in furnishing them with powerful weapons of defence and attack; but where its presence is not so evidentwhere it does not arrest our attention by endowing the animal with a power which enables it to simulate the effects of the lightning flash-can it exist without fulfilling some important purpose? Natura nihil agat frustra is a universally admitted axiom; nor must we presume otherwise even

when the subject we are investigating appears less endowed with useful applications.

Professor Galvani, of Bologna, in 1791, published a commentary "De Viribus Electricitatis in Motu Musculari," and announced those facts which laid the foundation of that science which bears his name. He then stated that a particular form of electricity, denominated by him animal electricity, existed in animals; and he believed he merely excited and rendered sensible this electricity by coating a nerve and muscle with metals, but did not regard the latter as the real source of the electricity.

This celebrated experiment is well known, I am sure, to all present, but is one of really so marvellous and remarkable a character that, repeat it as often as we may, it can never be looked at without a feeling of wonder and delight. I will take the legs of a frog, denuded of their skin, and attached by the lumbar nerves to a portion of the spine (fig. 5.*). Allowing them to rest on a glass

Fig. 5. The denuded legs of a frog, connected by the lumbar nerves to a portion of the spine. The nerves rest on the plate of zinc, Z; the toes on the plate of silver, S: the two plates are placed in communication by the curved wire, W.