AEROLITES. 131 



exhibitions. While these theories of the older philosophers have been shown to be 

 untenable, there is still great obscurity resting upon the question, though we have reason 

 to refer the phenomena to a cause exterior to the bounds of our atmosphere. Upon 

 this ground, the subject assumes a strictly astronomical aspect, and claims a place in a 

 treatise on the economy of the solar system. 



The first attempt accurately to investigate these elegant meteors was made by two 

 university students, afterwards Professors Brandes of Leipsic, and Benzenberg of Dussel- 

 dorf, in the year 1 798. They selected a base line of 46,200 feet, somewhat less than nine 

 English miles, and placed themselves at its extremities on appointed nights, for the pur- 

 pose of ascertaining their average altitude and velocity. Out of twenty-two appearances 

 identified as the same, they found 



7 under 45 miles 



9 between 45 and 90 miles 



5 above 90 miles 

 1 above 140 



The greatest observed velocity gave twenty-five miles in a second. A more extensive 

 plan was organised by Brandes in the year 1823, and carried into effect in the neighbour- 

 hood of Breslaw. Out of ninety-eight appearances, the computed heights were, 



4 under 15 miles 

 15 from 15 to 30 miles 

 22 30 to 45 

 33 45 to 70 



13 from 70 to 90 miles 

 6 above 90 miles 

 5 from 140 to 460 miles. 



The velocities were between eighteen and thirty-six miles in a second, an average velo- 

 city far greater than that of the earth in its orbit. 



The rush of luminous bodies through the sky of a more extraordinary kind, though a 

 rare occurrence, has repeatedly been observed. They are usually discriminated from 

 shooting stars, and known by the vulgar as fire-balls ; but probably both proceed from the 

 same cause, and are identical phenomena. They have sometimes been seen of large 

 volume, giving an intense light, a hissing noise accompanying their progress, and a loud 

 explosion attending their termination. In the year 1676, a meteor passed over Italy 

 about two hours after sunset, upon which Montanari wrote a treatise. It came over the 

 Adriatic Sea as if from Dalmatia, crossed the country in the direction of Rimini and 

 Leghorn, a loud report being heard at the latter place, and disappeared upon the sea to- 

 wards Corsica. A similar visitor was witnessed all over England in 1718, and forms the sub- 

 ject of oneof Halley's papers to the Royal Society. Sir Hans Sloane was one of its spectators. 

 Being abroad at the time of its appearance, at a quarter past eight at night, in the streets 

 of London, his path was suddenly and intensely illuminated. This, he apprehended at 

 first, might arise from a discharge of rockets ; but found a fiery object in the heavens, 

 moving after the manner of a falling star, in a direct line from the Pleiades to below the 

 girdle of Orion. Its brightness was so vivid, that several times he was obliged to turn 

 away his eyes from it. The stars disappeared, and the moon, then nine days old, and 

 high near the meridian, the sky being very clear, was so effaced by the lustre of the 

 meteor as to be scarcely seen. It was computed to have passed over three hundred geo- 

 graphical miles in a minute, at the distance of sixty miles above the surface, and was 

 observed at different extremities of the kingdom. The sound of an explosion was heard 

 through Devon and Cornwall, and along the opposite coast of Bretagne. Halley con- 

 jectured this and similar displays to proceed from combustible vapours aggregated on the 

 outskirts of the atmosphere, and suddenly set on fire by some unknown cause. But since 

 his time, the fact has been established, of the actual fall of heavy bodies to the earth from 

 surrounding space, which requires another hypothesis. To these bodies the term aerolites 

 is applied, signifying atmospheric stones, from o>)p, the atmosphere, and Atfloc, a stone. 



