METEORIC STONES AND SHOOTING STARS. 437 



from which the meteors seemed to emanate, was observed by those who 

 fixed its position among the stars to be in the constellation Leo ; and what 

 is very remarkable, this point was stationary among the stars during the 

 whole period of observation ; that is to say, it did not move along with 

 the earth in its diurnal rotation eastward, but accompanied the stars in their 

 apparent progress westward. It is not certain whether the meteors were, 

 in general, accompanied by any peculiar sound. A few observers reported that 

 they heard a hissing noise, like the rushing of a sky-rocket, and slight explo- 

 sions, like the bursting of the same bodies. Nor does it appear that any sub- 

 stance reached the ground which could be clearly established to be a residu- 

 um or deposite from the meteors. A remarkable change of weather from 

 warm to cold, accompanied the meteoric shower, or immediately followed it, in 

 all parts of the United States. 



From these circumstances and other particulars recorded, it has been infer- 

 red that had these meteors appeared to emanate from a point not in the direction 

 of the earth's rotation, they had not their origin in the atmosphere. By com- 

 paring observations made upon them in different latitudes, it was calculated 

 that their distance from the surface of the earth must have been above 2,000 

 miles. Assuming this result, which is, however, only an approximation, the 

 velocity with which they would enter the atmosphere may be computed. 



A body falling from the height of 2,000 miles would acquire by the attrac- 

 tion of gravity, at 50 miles from the earth, where it might be supposed to en- 

 ter the atmosphere, a velocity of four miles per second, being ten times the 

 velocity of a cannon-ball. It is contended, therefore, that on entering the at- 

 mosphere they would produce a sudden compression of air, and corresponding 

 evolution of heat. That the heat thus produced would render the bodies in- 

 candescent, and if they were combustible, would set them on fire. It is argued 

 that the quantity of heat which would be extricated from the air by such com- 

 pression would exceed that of the hottest furnace ; but that if the velocity 

 arising from the earth's motion were added to the proper velocity of the body 

 itself, which it must be, if these motions are contrary, there would then be an 

 effective velocity of fourteen, instead of four miles per second, and a still 

 greater amount of heat would be produced. It is argued that these meteors 

 must have been constituted of very light materials ; for if their quantity of 

 matter had been considerable, with so great a velocity they would have had 

 sufficient momentum to reach the earth, and the most disastrous consequences 

 might have ensued. From the apparent magnitude of many of the meteors, 

 and their probable distance, it was conjectured that they were bodies of a very 

 large size, although it was impossible to ascertain their magnitude with any 

 certainty. It was supposed that they were only stopped in the atmosphere, and 

 prevented from reaching the earth by transferring their motion to columns of air, 

 large volumes of which they would suddenly and violently displace. It was con- 

 sidered remarkable that the state of the weather, and the condition of the seasons 

 following this meteoric shower, were just such as might have been anticipated 

 from these disturbing circumstances of the atmospheric equilibrium. Such 

 were the speculations to which this remarkable phenomenon gave rise. 



Whatever be the origin of the phenomena of shooting stars, it cannot fail to 

 be interesting to learn the principal circumstances which observation has col- 

 lected respecting them. 



Their apparent magnitudes are very various. Sometimes they are not bright- 

 er or larger than the smallest star visible to the naked eye, and at other times 

 they surpass in splendor the most brilliant of the planets. Sometimes the glob- 

 ular form can be distinctly recognised upon them, and they are not distinguish- 

 able from the meteors called fire-balls. 



