fluid, which occasionally explodes through the thick solid outer shell.

A strong objection to this hypothesis of permanent revolving bodies, is derived from the great number of them there must be to answer all the appearances. Such a regular gradation is observed from those large meteors which strike all beholders with astonishment, and occur but rarely; down to the minute fires called shooting stars, which are seen without being regarded in great numbers every clear night; that it seems impossible to draw any line of distinction between them, or deny that they are all of the same nature. But such a crowd of revolving bodies could scarcely fail to announce their existence by some other means than merely a luminous train in the night; as, for instance, by meeting or justling sometimes near the earth, or by falling to the earth in consequence of various acci dents; at least we might expect they would be seen in the day-time, either with the naked eye, or by telescopes, by some of the numerous observers who are constantly examining the heavens.

Another argument of great weight, against the hypothesis that fire-balls are terrestrial comets, is taken from their great velocity. A body falling from infinite space toward the earth, would have acquired a velocity of no more than seven miles a second, when it came within 50 miles of the earth's surface; whereas these meteors seem to move at least three times faster. And this objection, if there be no mistake in regard to the velocity of the meteor, as I think there is not, absolutely oversets the whole hypothesis.

What then can these meteors be? The only agent in nature with which we are acquainted, that seeins capable of producing such phænomena, is electricity *. I do not mean that by what is already

Since the above was written, other ways of accounting for these meteors have been discovered and such indeed as, agreeing very well with all the phænomena, seem to be probable, or at least possible, solutions; which is far more than can be said of the notion from electricity; a notion that hardly agrees with any one of the numerous extraordinary circumstances attending these meteors; which have been observed in many instances to be the same as the stony masses that have often fallen through the atmosphere on various parts of the earth. For a particular account of such phænomena, see Meteoric Stones, section viii., of the present chapter. It is remarkable of the present large meteor, that its calculated velocity is nearly equal to that of the earth in its annual motion in the opposite direction.

known of that fluid, all the difficulties relative to meteors can be solved; as the laws, by which its motions on a large scale are regu lated in those regions so nearly empty of air, can scarcely, I imagine, be investigated in our small experiments with exhausted vessels; but only that several of the facts point out a near connexion and analogy with electricity, and that none of them are irreconcilable to the discovered laws of that fluid.

1. Electricity moves with such a prodigious velocity, as to elude all the attempts hitherto made by philosophers to detect it; but the swiftness of meteors, stating it at twenty miles a second, is such as no experiments yet contrived could have discovered, and which seems to belong to electricity alone. This is, perhaps, the only case in which the course or direction of that fluid is rendered perceptible to our senses, in consequence of the large scale on which these fireballs move.

2. Various electrical phænomena have been seen attending me. teors. Lambeut flames are described as settling on men, horses, and other objects; and sparks coming from them, or the whole meteor itself, it is said, have damaged ships, houses, &c. in the manner of lightning. These facts, I must own, are but obscurely related, yet still they do not seem to be destitute of foundation. If there be really any hissing noise heard while meteors are passing, it seems explicable on no other supposition than that of streams of electric matter issuing from them, and reaching the earth with a velocity equal to that of the meteor, namely, in two or three seconds. Accordingly, in one of our late meteors, the hissing was compared to that of electricity issuing from a conductor. The spark flying off so perpetually from the body of fire balls, may pos sibly have some connection with these streams. In the same manner the sound of explosion may be brought to us quicker, than if it were propagated through the whole distance by air alone. Should these ideas be well-founded, the change of direction which meteors seem at times to undergo, may possibly be influenced by the state of the surface of the earth over which they are passing, and to which the streams are supposed to reach. A similar cause may occasion the apparent explosion, the opening of more channels giving new vent and motion to the electric fluid. May not the deviation and explosion which appear to have taken place in the fire-ball of the 18th

of August over Lincolnshire, have been determined by its approach towards the fens, and an attraction produced by that large body of moisture?

3. A further argument for the electric origin of meteors is deduced from their connection with the northern lights, and the resemblance they bear to these electrical phænomena, as they are now almost universally allowed to be, in several particulars. Instances are recorded, where northern lights have been seen to join and form luminous balls, darting about with great velocity, and even leaving a train behind like the common fire-balls. This train I take to be nothing but the rare air left in such a highly electrified state as to be luminous; and some streams of the northern lights are very much like it. The aurora borealis appears to occupy as high, if not a higher, region above the surface of the earth; as may be judged from the very distant countries to which it has been visible at the same time; indeed, the great accumulation of electric matter seems to lie beyond the verge of our atmosphere, as estimated by the ces. sation of twilight. Also with the northern lights a hissing noise is said to be heard in some very cold climates; Gmelin speaks of it in the most pointed terms, as frequent and very loud in the northeastern parts of Siberia; and other travellers have related similar facts.

But, in my opinion, the most remarkable analogy of all, and that which tends most to elucidate the origin of these meteors, is the direction of their course; which seems, in the very large ones, at least, to be constantly from or toward the north or north-west quar. ter of the heavens, and indeed to approach very nearly to the present magnetical meridian. This is particularly observable in those meteors of late years whose tracks have been ascertained with most exactness; as that of November 26, 1758, described by Sir John Pringle; that of July 17, 1771, treated of by M. Le Roy; and this of the 18th of last August. The largest proportion of the other accounts of meteors confirm the same observation, even those of a more early period; nay, I think, some traces of it are perceivable in the writings of the ancients. Whether their motion shall be from the northern quarter of the heavens or towards it, seems nearly indifferent, as the numbers of those going each way are not very unequal; I consider them in the former case as masses of the electric fluid repelled or bursting from the great collected body of it in the

north; and in the latter case, as masses attracted to that accumulation; a distinction probably much the same in effect, as that of positive and negative electricity near the surface of the earth.

This tendency toward the magnetic meridian, however, seems to hold good only with regard to the largest sort of fire-balls; the smaller ones move more irregularly; perhaps because they become farther within the verge of our atmosphere, and are thus more exposed to the action of extraneous causes. That the smaller sort of meteors, such as shooting stars, are really lower down in the at. mosphere, is rendered very probable by their swifter apparent motion; perhaps it is this very circumstance which occasions them to be smaller, the electric fluid being more divided in more resisting air. But as those masses of electricity, which move where there is scarcely any resistance, so generally affect the direction of the magnetic meridian, the ideas which have been entertained of some ana logy between these obscure powers of nature, seem not altogether without foundation.

If the foregoing conjectures be just, distinct regions are allotted to the electrical phænomena of our atmosphere. Here below, we have thunder and lightning, from the unequal distribution of the electric fluid among the clouds; in the loftier regions, whither the clouds never reach, we have the various gradations of falling stars; till, beyond the limits of our crepuscular atmosphere, the fluid is put into motion in sufficient masses to hold a determined course, and exhibit the different appearances of what we call fire-balls; and probably at a still greater elevation above the earth, the electricity accumulates in a lighter less condensed form, to produce the wonderfully diversified streams and corruscations of the aurora borealis. [Phil. Trans. Abr. vol. xv. year 1784.

SECTION VII.

Fiery Meteors, with Balls that have descended to the Earth.

1. Account of a fiery Meteor seen, at Jamaica, to strike into the Earth.

By Mr. Henry Barham, F.R.S.

ABOUT the year 1700, as I was riding one morning about three miles north-west from St. Jago de la Vega, I saw a ball of fire, appearing to me of the size of a bomb-shell, swiftly falling down with a great blaze. When I arrived where it fell, I found the people wondering at the ground being broken in by a ball of fire, which they said fell down there. I observed there were many holes in the ground; one in the middle, of the size of a man's head, and five or six smaller holes round about it, of the size of a man's fist; and so deep, especially the largest, as not to be fathomed by what long sticks they had at hand. It was observed, that the green grass was perfectly burnt near the holes, and a strong smell of sulphur remained thereabouts for a good while after.

We had a very rainy night before, with much lightning and thunder, which is frequent in Jamaica, often killing cattle in the fields. These claps are much louder and stronger than any in Europe, and our showers of rain are also more violent. We have lightning all the year round; but our great rains are in the nonths of May, August, and October.

Our island is full of mines, and, I question not, very rich. It is very subject to earthquakes; several happening every year, especially after great rains, which fill up all the great cracks in the surface of the earth for in a very dry time, they are so very large, deep, and gaping so open and wide, that it is dangerous to ride over some parts of the Savannas, for fear a horse should get his legs into them. Our earthquakes make a noise or rumbling in the earth, before we feel the shake; and seem to run swiftly to the westward.

[Phil. Trans. 1718.

* See for other instances, chap. xliii. sect. iv.