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can cause its spark to accumulate in intensity and power, can direct this for the fusion and combustion of metals, the paralysis or death of organic bodies, and thus imitate, upon a microscopic scale, the well-known effects of the resistless flash of lightning from the heavens.

He discovers that substances, having a redundance of electricity, or being charged with electricity, invariably endeavor to communicate or to discharge it to others that are deficient, and when this restoration of equilibrium or discharge is suddenly and extensively effected, it is attended by intense heat and vivid light.

Further experiments inform the chemist, that such restoration of the equilibrium or discharge of electricity, may be either arrested, opposed, or facilitated by several distinct substances; or, as in the case of Heat so in this of Electricity, there are non-conductors, bad conductors, and good conductors.

Anhydrous air is a non-conductor, earthy substances are bad conductors, water and metallic ores are better conductors, and pure metals the best conductors of imponderable Electricity.

The greatly desiccated atmosphere of Summer, and of the first days of Autumn, though not an absolute nonconducting, is an extremely imperfect conducting medium of electricity; and this agent, by some recondite property, appears to accumulate in the atmosphere, probably during the incipient condensation of its watery vapor into the mysterious form of clouds; these clouds are regarded as aqueous volumes highly charged with electricity, floating in the vast and generally desiccated volume of the air; or, in other words, a volume of dry air, capable of supporting the clouds, yet incapable of depriving them of their electrical charge.

The clouds endeavor to discharge this electrical surplus to the solid earth and flowing waters; the air will not conduce to this effort, and eventually the surplus or accumulation in the clouds is so excessive, is so powerful, that it suddenly pierces or disrupts the air by a flash of lightning to the earth and waters.

This lightning is succeeded by thunder, a sound produced by the immediate and violent collapse of the disrupted air, to effect the restoration of its own equilibrium; "like as when an arrow is shot at a mark, it parteth the air which immediately cometh together again, so that a man cannot know where it went through."

The time which elapses between the flash of lightning and the explosion of thunder, affords the means of calculating the distance of the storm, for light, moving with the incomprehensible velocity of 192,000 miles in a second, the time that it takes to traverse any terrestrial distance may be considered as nothing, but sound travels only at the rate of about 380 yards in a second.

The flash and the thunder are really simultaneous, but the former is instantly seen, whilst the other requires a second of time to traverse 380 yards; therefore the interval that elapses between the two phenomena, being multiplied by this number, will give the distance of the

storm.

Thus, if the flash take place six seconds before the thunder is heard, then 6×380=2280 yards, or one mile, two furlongs, and eighty yards, which is the distance of the storm from the observer.

Let it be particularly remembered, that this calculation regards a discharge of lightning that has happened, and it must not be considered as a measure of the removal of the observer from danger, for other discharges may rapidly happen much closer, as thunder clouds are frequently extended over a great extent of terrestrial surface, and very frequently two or three flashes of lightning are seen, apparently simultaneously, in the different parts of the atmosphere.

When lightning flashes in a long, irregular, angular, gnarled or knotted stream, these appearances announce its passage through an extensive volume of the atmosphere; but when it flashes in a short, straight, or direct line of vivid light, it may be considered to have disrupted a comparatively limited portion of the atmosphere.

In the first case the flash would be seen some time before the thunder would be heard, and in the second case the flash would be instantly followed by the thunder.

The tree in the background is supposed to have determined the discharge of lightning from a cloud hovering at a considerable distance; the flash is therefore long and irregular; and a spectator of the storm, if standing near the tree, would first hear the thunder from the collapse of the air near its summit, then from beyond this, afterwards from a more remote portion, and ultimately from the volume of the cloud, whence the light

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ning first broke forth; the thunder, therefore, would not fall upon the ear as one direct and crashing sound, but as an irregular succession of sounds, or loud rumbling noise.

"This irregularity in the passage of lightning is sometimes so considerable, that the thunder is actually lost to the ear at one moment, and heard again at another, and this three or four times successively in the same clap;" and this, conjoined with the reflection of the sound, or its reverberation from mountain, hill, and valley, at one instant pealing loudly, at another, booming gently, at length murmuring faintly, and ultimately dying away, are extremely impressive concomitants and attendants of the original phenomenon of the flash.

The tree in the foreground of the engraving, is supposed to have determined the discharge of lightning from a cloud hovering at a little distance, the flash is therefore short and regular, and a spectator of the storm, if standing near this tree, at the moment of the flash, would hear the full thunder of the collapsing air, as one loud and terrible crash, which in a few seconds after, would reverberate from surrounding objects, and ultimately die away in silence.

When the chemist causes electricity to pass through large and small intervals of air, the vivid sparks in their disruptive transit, present upon a microscopic scale appearances precisely similar to those of extensive and limited flashes of lightning.

An appearance of two distinct flashes or streams is very frequently produced at a considerable distance from each other, when part of a long, sharp, angular flash is hidden by an intervening cloud, and the sudden and universal flash, or "sheet lightning," appears to result from a discharge which is more perfectly concealed.

The bright flashes which occur during summer and autumnal evenings, unaccompanied by thunder, are of this kind, and it is supposed that on account of their vast distance from the earth, that the sound of the thunder must be lost in its passage.

"The appearance of the heavens during a thunderstorm, the manner in which the clouds assemble, and attract and repel each other, the circumstance of their rising against the wind, and traversing the upper regions of the atmosphere in a variety of contrary directions, are phenomena which it is not difficult to explain by reference to the general laws of electricity."

Many of these have been discovered by the great philosopher of the present day, and regarding his extraordinary knowledge of Electricity and Chemistry, it has been justly said, that, "in point of originality in devising experiments, skill in carrying them into effect, and perspicuity in tracing out and unraveling the complicated relations of the new truths which are elicited, he stands, if not unrivaled, at least unsurpassed."

Upon known laws of electricity, as excited in the laboratory, the peculiar fringed appearance of a thundercloud may be explained, and also the irregular portions which it projects towards the earth, whilst its upper surface is generally smooth, and well-defined.

"We sometimes observe that a number of such clouds of small dimensions, coalesce into a larger one, moving swiftly in all directions, and darting flashes from one to the other, whilst the wind rises and often blows in squalls; the lightning is more frequent as the clouds aggregate,