Faraday’s description of a Gymnotus, paralyzing and seizing its prey, is too graphic and important to be omitted.
“The Gymnotus can stun and kill fish which are in very various positions to its own body; but on one day, when I saw it eat, its action seemed to me to be peculiar. A live fish, about five inches in length, caught not half a minute before, was dropped into the tub. The Gymnotus instantly turned round in such a manner as to form a coil, inclosing the fish, the latter representing a diameter across it; a shock passed, and there, in an instant, was the fish struck motionless, as if by lightning, in the midst of the waters, its side floating to the light. The Gymnotus made a turn or two to look for its prey, which, having found, he bolted, and then went about searching for more. A second smaller fish was given him, which being hurt in the conveyance, showed but little signs of life, and this he swallowed at once, apparently without shocking it. The coiling of the Gymnotus round its prey had, in this case, every appearance of being intentional on its part, to increase the force of the shock, and the action is evidently well suited for that purpose, being in full accordance with the well-known laws of the discharge of currents in masses of conducting matter; and though the fish may not always put this artifice in practice, it is very probable he is aware of its advantages, and may resort to it in cases of need.”[150]
Animal electricity has been proved to be of the same character as that derived from other sources. The shock and the spark are like those of the machine; and the current from the animal, circulating around soft iron, like galvanic electricity, has the property of rendering it magnetic.
It is important that we should now review these conditions of electrical force in connexion with the great physical phenomena of nature.
It is sufficiently evident, from the results which have been examined, that all matter, whatever may be its form or condition, is for ever under the operation of the physical forces, in a state of disturbance. From the centre to the surface all is in an active condition: a state of mutation prevails with every created thing; and science clearly shows that influences are constantly in action which prevent the possibility of absolute repose.
Under the excitement of the several agencies of the solar beams, motion is given to all bodies by the circulation of heat, and a full flow of electricity is sent around the earth to perform its wondrous works. The solar influences, which regulate, and possibly determine, every physical force with which we are acquainted, are active in effecting an actual change of state in matter. The sunbeam of the morning falls on the solid earth, and its influence is felt to the very centre. The mountain-top catches the first ray of light, and its base, still wrapt in mists and darkness, is disturbed by the irradiating power. The crystalline gems, hidden in the darkness of the solid rock, are dependent, for that form which makes them valued by the proud and gay, on the influence of those radiations which they are one day to refract in beauty. The metals locked in the chasms of the rifted rocks are, for all their physical peculiarities, as dependent on solar influence as is the flower which lifts its head to the morning sun, or the bird which sings “at heaven’s high gate.”
Let us, then, examine how far electricity, as distinguished from the other powers, acts in producing any of these effects.
We find electricity in the atmosphere, which the electrical kite of Dr. Franklin proved to be identical with that principle produced by the friction of glass. In the grandeur and terror of a thunderstorm, many see nothing but manifestations of Almighty wrath. When the volleys of the bursting cloud are piercing the disturbed air, and the thunders of the discharge are pealing their dreadful notes above our heads, the chemical combinations of the noxious exhalations arising from the putrefying animal and vegetable masses of this earth are effected, elements fitted for the purposes of health and vegetation are formed, and brought to the ground in the heavy rains which usually follow these storms. Science has taught man this—has shown him that the “partial evil” arising from the “winged bolt” is a “universal good;” and, more than this, it has armed him with the means of protecting his life and property from the influence of lightnings. So that, like Ajax, he can defy the storm. By metallic rods, carried up a chimney, a tower, or a mast, we may form a channel through which the whole of the electricity of the most terrific thunder-cloud may be carried harmlessly into the earth or the sea; and it is pleasing to observe that at length prejudice has been overcome, and “conductors” are generally attached to high buildings, and to most of the ships of our navy.[151] It was discovered that the devastating hailstorms of the south of France and Switzerland, so destructive to the vineyards and crops, were accompanied by evidences of great electrical excitation, and it was proposed to discharge the electricity from the air by means of pointed metallic rods. These have been adopted, and, it is said, with real advantage—each rod protecting an area of one hundred yards. Thus it is that science ministers to our service; and how much more pleasing is it to contemplate the lightning, with the philosopher, as an agent destroying the elements of pestilence, and restoring the healthfulness of the air we breathe, than with the romancer, to see in it only the dreaded aspect of a demon of destruction.
The laws which regulate the spread of a pestilence are unknown. The difficulties of the investigation are great, but they are by no means insurmountable. A plague passes from the east to the west across the world—it spreads mourning over the gayest cities, and sorrow sitteth in the streets. The black death rises in the Orient: it goes on in unchecked strength, and only finishes its course when it has made the circuit of the civilized world. The cholera spreads its ebon wings—mankind trembles—watches its progress, and looks upon the path which is marked by the myriads of the dead, who have fallen before the dire fiend. The diseases pass away—the dead are buried, and all is forgotten. The rush and the riot of life are pursued: and until man is threatened with another advent, he cares not to trouble himself. Accompanying the last visitation, there appear certain peculiar meteorological conditions, which point a line of inquiry. It may or may not be the path which leads to the truth, but certainly its indications are worthy of careful examination. It may be asked, can weak man stop a pestilence; can a mortal’s puny hand retard the afflictions of the Almighty? The question asked—it must be answered in reverence, yet without fear. No human power can produce a change in the physical conditions of the earth, or of the air; and if our diseases are connected with those changes, as beyond all doubt a number of them are, they lie above man’s control. But when there are indications that causes secondary to these are producing some dire effect, and when we know that these secondary causes may be modified, it is sufficient evidence to prove that man is permitted to control thus far the afflictions which are sent to try his powers.