﻿510 Mr. D. Vaughan on Secondary Planets 



not gradually, but in a paroxysmal manner. These results, to- 

 gether with some facts respecting the light of meteors, furnished 

 the chief grounds on which I have hitherto maintained that 

 temporary stars are great meteoric displays attending the dila- 

 pidation of a world, its fragments sweeping through the atmo- 

 sphere of a greater central orb. More positive evidence is 

 afforded by observations made on the star which displayed its 

 ephemeral brilliancy in the constellation of Corona in 1866. 



That hydrogen is the main constituent of the highest part of 

 the solar atmosphere was first inferred by Dr. Stoney from 

 theoretical principles, but has been proved more conclusively by 

 the observations of late years. As the same light gas is now 

 known to exist in most of the great orbs of space, it must 

 form the chief part of their external envelopes, in obedience to 

 the law which gives fluids a position depending on their den- 

 sity, and which, from the great rarefaction and feeble expan- 

 sibility of the uppermost atmospheric strata, must overrule 

 the tendency which the power of diffusion exerts for produ- 

 cing a uniform mixture of all aeriform collections of matter. 

 From their position in the outward envelopes of all great ce- 

 lestial bodies, the most rare and attenuated elements must act 

 a most conspicuous part in such great meteoric displays as may 

 be expected to occur when a primary or a secondary planet, 

 gradually introduced into too small an orbit, undergoes either a 

 total or a partial dismemberment, and sends its innumerable 

 fragments through the atmosphere of the central orb. As the 

 fragments sweeping through the upper atmospheric stratum of 

 the latter body would escape immediate precipitation to its sur- 

 face, and continue the production of heat and light during many 

 revolutions, and as large meteors must require some time to 

 partake of the high temperature which they impart to the re- 

 sisting medium, it may be reasonably expected that the peculiar 

 characters of hydrogen and of other rare gases would be im- 

 pressed on the vast flood of light sent forth during these ex- 

 hibitions of meteoric brilliancy. 



This explanation accords with the fact that the temporary 

 star of 1866 exhibited, not only the ordinary spectrum of side- 

 real bodies, but also another, consisting of four bright lines, two 

 of which indicated the presence of hydrogen gas in a high state 

 of incandescence. The eminent observer to whom science is 

 indebted for this discovery, ascribes the phenomenon to effects 

 of burning hydrogen ; but the cause would certainly be inade- 

 quate to call forth the wonderful brilliancy of the star, even 

 though the gases participating in the combustion could meet 

 in the exact proportions required for chemical union,, and no 

 inert elements reduced the temperature by sharing the heat 



