On the Sun, Moon, ami other heavenly Bodies. 167 



whether each of the planets is furrounded by fuch a fubtile, 

 mafs or not, is another queftion, which our experience hi- 

 therto has left in the greateft uncertainty, and refpe£ting 

 which we can form only probable conclufipns a priori. 



If we confider the heavenly bodies at the period of their 

 formation, it muft naturally occur, that, when created, 

 they muft have had atmofpheres j for, as foon as the fixed 

 ftars began to burn, let their iubllance be what it might, a 

 great many particles muft have thereby been dilengaged from 

 them, and have formed a kind of atmofpheres. Now, if each 

 of thefe fixed ftars is furrounded by a certain number of pla- 

 nets, its aftion on them muft have feparated from them abun- 

 dance of particles, which, on account of their levity, would 

 immediately afcend and form atmofpheres around them : but 

 as the difengaged particles could not all have the fame gravity, 

 the lighter would rife to a greater height than the heavier; 

 and, on that account, the rarity of thefe atmofpheres mufl 

 have incrcafcd according as the diftance from the. planet was 

 greater. The diii'erent aqueous, earthy, faline, fulphureous, 

 and mineral particles form therefore in the air, belonging 

 to each planet, what ought properly to be called its atmo- 

 fphere . 



That the fun has an atmofphere is admitted by all the mo- 

 dern aftronomers. Peyroux de la Coudreniere has in parti- 

 cular aflferted, in modern times, and his opinion has been 

 almoft univerfallv adopted, that the fun is not a ball of fire, 

 but that his light comes entirely from a luminous atmofphere 

 by which he is furrounded, and which is filled with a highly 

 inflammable vapour that forms a continual covering of fire. 

 According to him, therefore, the fnn is a prodigious burning 

 mirror, which can effctt with lefs wafte much more than it 

 could do were it a globe of fire. M. Schroter concludes alfo, 

 from his obfervations, that the light of the fun arifes from the 

 hmiinous matter by which he is furrounded ; fo that hopes 

 axe entertained that, in the courfe of time, by making fre- 



* Heinfius, in his Bitrachitingen iiber Jen kometcn von 1744, ^fl^ff- 

 biiygh 1774, 4to. p. loi, makes the boundaries of each atmofphere to be 

 in that point where the particles extricated from the planet are in equili- 

 brium bctwctn it and the fun. 



qucnt 



