156 On the iwinkling of the Fixed Stars. 



Art. XXIV. — On the twinkling of the Fixed Sta7-s. 



Mti"Haven, January 20, 1822, 



Mr. Silliman, 



Sir, 



In perusing Bonnjcastle's Introduction to Astronomy, 

 I was struck vvilli the following solution of the phenonnenon 

 of the scintillalion, or twinkling of the fixed stars. Page 

 42d, he says, " the fixed stars are distinguished from the 

 planets by being more bright and luminous, and by contin- 

 ually exhibiting that appearance which is called the scintil- 

 lation or twinkling of the stars. This probably arises from 

 their appearing so extremely small, that the interposition 

 of any minute substance, of which there are many constant- 

 ly floating in the atmosphere, deprives us of the sight of 

 them ; but as the interposed body soon changes its place, 

 we again see the star ; and this succession being perpetual 

 occasions the twinkling." Whether this be the commonly 

 received opinion, on this subject, among astronomers, or 

 not, I am not sufficiently conversant with their works to 

 decide ; but from its being assigned by so distinguished an 

 astronomer as Mr. Bonnycastle, I conclude that it is one 

 of the best that have been given. To my mind this solu- 

 tion is very unsatisfactory. Without farther proof of the 

 fact, the existence of these floating substances in numbers, 

 and of size sufficient to produce this phenomenon, is scarce- 

 ly credible. But admit that they exist, why do they not 

 produce similar phenomena in their transits over the faces 

 of the planets? Farther,! apprehend thattheeffi^ctof the in- 

 terposition of these substances between the eye and the stars, 

 which would be as Mr. B. observes, to deprive us of the 

 sight of them, does not accord with the fact, or with the 

 phenomenon of scintillation. In my view, the star does 

 not disappear in its scintillations, but is constantly visible; 

 and its twinkling seems to be the effect of successive ema- 

 nations of light ; resembling the waving of a blaze by the 

 wind. Though but a novice in astronomy, I will suggest a 

 conjecture on this subject, which, to my mind, is much 

 more plausible; certainly less embarrassed with objections 



