A CATALOGUE OF OBSERVATIONS OP LUMINOUS METEORS. 15 



series, in which he found that a piece of lime, less than half an inch in dia- 

 meter, in the flame of the oxyhydrogen blowpipe, had, when viewed in a clear 

 evening, at the distance of half a mile, an apparent diameter twice that of the 

 Full moon, show conclusively that no reliance can be placed upon calculations 

 founded upon the apparent diameter of bodies in a state of incandescence. 



10. The apparent form of the meteor, that of a cone moving base fore- 

 most, may have been due to its great angular velocity, combined with the 

 effect of irradiation above referred to. The impression made upon the eye 

 by the incandescent body itself, would doubtless be greater than that made 

 by the sphere of light surrounding it. Consequently we should continue to 

 see the body itself after the impression of the mere glare had faded awav ; 

 so that the apparent diameter of the end of the tail may represent the actual 

 angular diameter of the body. 



11. The invisibility of the meteor to persons at Philadelphia and vicinity, 

 was no doubt due to the position of the sun, the direction of which then 

 coincided with that of the meteor. 



No. 2 — Abstract of a paper by R. P. Greg, Esq., F.G.S., in the Philoso- 

 phical Magazine, April 1860, "On Luminosity of Meteors from Solar Re- 

 flexion." 



With reference to the cause of the luminosity of shooting stars, the author 

 proposes to prove that their luminosity cannot arise from solar reflexion, 

 a theory partially supported by Sir J. Lubbock and others. He observes 

 that the very sudden appearance and disappearance of shooting-stars and 

 small meteors, and their general resemblance on a small scale to comets which 

 shine by solar reflexion, certainly favour the idea, either that suddenly enter- 

 ing the cone of the earth's shadow they are instantly eclipsed, or conversely, 

 become visible as they emerge from it; or secondly, previously self-luminous 

 in planetary space, they may become suddenly extinguished on entering the 

 denser atmosphere of the earth ; or thirdly, they may suddenly become visi- 

 ble and luminous only on entering the earth's atmosphere by friction and 

 compression, by rapid absorption of oxygen and sudden chemical action, or 

 by electrical excitation. 



The author then refers to Sir J. Lubbock's paper in the Philosophical 

 Magazine for February 1848, and shows by a different treatment how un- 

 likely, if not impossible, it is that ordinary shooting-stars (those not show- 

 ing symptoms of active ignition within the lower limits of the earth's atmo- 

 sphere) can ever shine by reflected solar light ; and this simply from the fact 

 that they would be too far off for us to observe such small bodies, at even 

 the minimum distance at which (at certain times and places on the earth's 

 surface when and where we know they are very frequently seen) they 

 actually could be so visible ; and concludes his paper by remarking that, if 

 his calculations, &c. be correct, the majority of shooting-stars do not shine 

 by reflected light. 



No. 3. — M. Schmidt on the Luminous Trains left by Meteors, &c. 



M. Schmidt repeats an observation of M. Faye's in the ' Comptes Rendus,' 

 vol. xxxii. p. 667, relative to the small amount of moveability in the tails or 

 luminous trains not unfrequently left by meteors, which seems to prove that 

 the former must be found in the atmosphere belonging to and surrounding 

 the earth, and not in the firmament which lies beyond it. M. Faye observed 

 one of these tails through the telescope, and he saw it " lingering for more 

 than three minutes, without changing its place very perceptibly. — Other 

 observers have observed them to remain for more than seven minutes." M. 



