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Such observations have occasionally been made, and such alti. tudes remarked with all desirable care and circumspection : and especially by M.M. Benzenberg and Brandes.
The meteors in this case were observed from a base of 46,200 feet F. or 2.1 German geographical miles, fifteen of which make a degree: their height was from four to thirty of those miles; the mean height about eleven, or near fifty English miles. The velo. city of two of them was from four to six miles, or about twentytwo English miles in a second. One was brighter than Jupiter, and was 450 miles distant.
In a second paper Dr. Benzenberg gives two instances in detail. September 15. A shootin, star of the fifth magnitude. Elevation of the beginning 707 geographical miles, of the end 8.2. Len th of the path 1.5 miles. Longitude of the place of disappe rance 28° 3'; latitude 530 22. Observed by Brandes, in Ekwarden, and Benzenbery, in Ham, near Hamburg : length of the base fourteen miles. October 3. Another of the fourth magnitude observed by the same persons. The termination 7.1 geographical miles above the earth. Longitude 27° 7' ; latitude 53° 5'. These observations shew, says Dr. Benzenberg, that a long base will furnish as accurate a comparison as a shorter one; that even meteors of the fourth and fifth magnitude may be seen at places distant above fourteen geographical miles from each other; and they confirm the former observations made at Gottingen with a base of but one or two miles.
We will only further observe, as in truth we have partly hinted at before, that Dr. Benzenberg did not believe these small meteors to be of the same nature as the larger. His opinion concerning fiery balls was, that they were revolving bodies distinct from the earth : but he conceived the train of shooting stars to be too numerous for such independent revolving bodies; and with Dr. Chladni objected, that, in such case, they would not appear to ascend as they are often found to do as well as to descend. There are, at the same time, various difficulties in the way of regarding them as mere electric scintillæ.
See Gilbert vi. 224, x. 212.
very clearly explained, though not difficult to be either given or comprehended.
By far the greatest part of the light we possess is derived from the sun: but there are also numerous kinds of bodies that possess it in a latent or dormant state, and readily give it forth upon being properly excited, or under a proper elevation of tem. perature; and others that give it forth spontaneously, in the com. mon temperament of the atmosphere. Of the former division are oils, bitumens, vinous spirits, carbon, phosphorus, and hydrogen gas. of the latter various vegetable and animal substances, on the commencement of putrefaction, which consists in a slow de. composition not wholly unlike combustion ; touch.wood, which is wood in a peculiar state of decay; various species of boletus or agaric, and especially that which is denominated spunk; and a multiplicity of worms and insects in a state of perfect health, as pyrosmas, phloades, fire-balls, glow-worms, and elaters.
It was at one period, as we shall find in the ensuing section, a very general opinion among the learned, that the luminous appear. ances we refer to, were in every instance produced by phospho. rescent josects and worms; but the situations and periods of the year in which they are perhaps most frequently met with, together with a variety of other circumstances, strongly militate against such an idea ; and sufficiently prove, that the source of many of these meteors is to be sought for in the light exhaled by the decom. position of animal or vegetable materials, magnified, and deepened in hue by the haze or vapoury atmosphere of the moist and swampy low lands in which they are chiefly beheld; and which, in consequence of their moisture and swampiness, are particularly favourable to the process of decomposition,
We may thus account for many of them, and particularly for those that evince no sensible heat during their illumination; for the light exhaled or thrown off from the substances we now allude to, possesses no sensible heat whatever.
It not upfrequently happens, however, that a greater or less degree of heat, a proof of actual though slow combustion, hag been evinced during the existence of these phænomena; as also that they have extended more widely than any local decomposition
* See for a fuller account of these curious facts, Books II. and III. of the present work,