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XXXII. The Tails of Comets. 



By E. VansittartNeale. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 



I VENTURE to offer an explanation of the remarkable 

 phenomena presented by the tails of comets, so simple 

 that, considering the number of eminent astronomers who 

 have turned their attention to this subject, and to whom it has 

 remained a mystery, I am almost afraid to suggest my expla- 

 nation, lest it should prove a sort of scientific mare's nest. 

 Still, since I cannot see where it fails, while the subject is one 

 of considerable interest, I have determined to run the risk of 

 some eye more penetrating than my own discovering my error, 

 if there is one. 



My explanation rests on the interaction of three force.-, of 

 which two are known to exist, while the existence of the third 

 may, I think, be reasonably assumed. These forces are: — 

 (1) the force which urges the comet towards the sun; (2) the 

 expansive force of the heat of the sun; (3) the resistance of an 

 atmosphere surrounding the sun. 



That there is such an atmosphere extending many hundred 

 thousand miles from the sun's centre we know, because it can 

 be seen. Hoav much further it may extend in a condition in 

 which it is invisible we do not know; but, considering the dis- 

 tance to which the atmosphere surrounding the earth is known 

 to extend by its action on meteoric bodies, we may, I think, 

 reasonably assume the existence of an invisible solar atmo- 

 sphere, extending far beyond the limits of the visible atmo- 

 sphere; and if this is assumed, we obtain an easy explanation 

 of the phenomena of comets' tails. 



The changes in a comet which give rise to its tail begin, 

 according to the account given by Mr. Higgins in his excel- 

 lent article on Comets in the current number of the c Nineteenth 

 Century/ by jets of a gaseous nature ejected towards the sun, 

 i. e. in the direction determined by the expansive force of the 

 sun's heat, acting on the comet, combined with the moving- 

 force of the comet. But soon, he says, these jets bend round, 

 as if they were carried back by a strong wind, and form an 

 envelope round the body of the comet and a cone behind it. 

 Just so. It is what would happen to a man dressed in a loose 

 robe and running rapidly through the air. His dress, though 

 moving with him, would stream behind him, because it expe- 

 rienced more resistance than his body from the air. The jets 



