362 Mr. D. Vaughan on the Solar Spots. 



diminish weight and pressure only in certain localities, yet, from 

 the conditions of equilibrium in gases, it must reduce the density 

 of all parts of the sun's luciferous atmosphere, and lead to a cor- 

 responding diminution of his lustre. Accordingly, when large pla- 

 nets describe orbits of small size and great eccentricity, they must 

 exert a considerable influence on the illuminating power of the cen- 

 tral orb, retarding the great conflagration when they are near, and 

 allowing it to proceed with more vigour when they are most distant. 

 In condensing in the regions over which suns and worlds have 

 passed, the fether must be withdrawn from more distant locali- 

 ties, and be there compelled to assume a more rarefled condition. 

 Accordingly planets, whose planes deviate much from the direc- 

 tion of their sun's progressive motion, only curtail the supplies 

 of his etherial fuel, and diminish the amount of heat and light 

 which he di0"uses around him. It is only in this way that the 

 members of our own system can influence the production of light 

 in our central luminary ; and the slight efl"ects which they occa- 

 sion are exhibited in the periodicity of the solar spots. In con- 

 sequence of the great mass of Jupiter, his effects on the vast 

 illumination must preponderate over that of the other planets ; 

 and it may be observed, the period of his revolution does not 

 differ very much from the interval between the times at which 

 the spots appear in the greatest numbers. 



Modern observations prove that the sun's spots are not only 

 deficient in light, but also that they have a lower temperature 

 than other parts of his surface. If, therefore, they are caused 

 by exhalations from the solar mass, we may reasonably conclude 

 that the gas which rises from his internal regions, only serves to 

 interrupt his heating and illuminating action. If they are to be 

 regarded as indications of a dark atmosphere beneath the lumi- 

 nous one, the mere situation of this dark envelope would be an 

 evidence that it was derived from the sun himself, and would in- 

 validate the opinion that he emits combustible gases. Indeed, 

 if his heat and light were maintained by gases expelled from him 

 by the high external temperature, the fuel must be supplied in 

 the greatest abundance when the fire is most violent ; and the 

 great conflagration should steadily increase until the solar mass 

 was entirely consumed, or continually decline until it sunk to 

 perpetual darkness. Supported by the medium which pervades 

 all space and burns in accordance with fixed laws, the brightness 

 of suns can only fluctuate in obedience to the influence of attend- 

 ant worlds ; and future observations on the variable stars with 

 better photometric instruments than we can now command, may 

 yet enable astronomers to trace the movements of planets, in sy- 

 stems far too distant to be even explored with the telescope. 

 Cincinnati, Ohio, March 30, 1858. 



