6S0 PHILOSOPHICAL TRANSACTIONS. [ANNO 1785. 



rays. When spirits of wine are in a similar manner brought within the cir- 

 cuit of a battery, a similar effect may be discovered; its particles diverge in 

 several directions, displaying a most beautiful golden appearance. The metallic 

 calces are, of all bodies, those which are rendered phosphoric with the greatest 

 difficulty. But even these may be scattered into a shower of red luminous par- 

 ticles by the electric stroke. — Norwich, Oct. 7, 1784. 



Postscript by the Rev. Dr. Price. — By the phosphoric force mentioned in the 

 last paragraph of this paper, Mr. Morgan appears to mean, not the force with 

 which a phosphoric body emits, but the force with which it absorbs and retains 

 light. This last force is proportioned to the degree of attraction between the 

 phosphoric body and light; and therefore must, as Mr. Morgan observes, be 

 weakest when it emits so freely the light it has imbibed, as not to retain those 

 rays which adhere to it most strongly. According to Mr. Morgan's theory, 

 these rays are those which are least refrangible. The observations and experi- 

 ments in this paper seem to render this theory probable. It is however an 

 objection to it, that the less refrangibility of rays seems to imply a less force of 

 attraction between them and the substances which refract them ; but it should 

 be considered, that possibly the force of cohesion, which unites the rays of light 

 to bodies, may be a different power from that which refracts them. 



XII. On the Construction of the Heavens. By Wm. Herschel, Esq., F. R. S. 



p. 213. 



That the milky way is a most extensive stratum of stars of various sizes admits 

 no longer of the least doubt ; and that our sun is actually one of the heavenly 

 bodies belonging to it is as evident. I have now viewed and gaged this shining 

 zone in almost every direction, and find it composed of stars whose number, by 

 the account of these gages, constantly increases and decreases in proportion to 

 its apparent brightness to the naked eye. But in order to develope the ideas of 

 the universe, that have been suggested by my late observations, it will be best 

 to take the subject from a point of view at a considerable distance both of 

 space and of time. 



Theoretical view. — Let us then suppose numberless stars of various sizes, 

 scattered over an indefinite portion of space, in such a manner as to be almost 

 equally distributed throughout the whole. The laws of attraction, which no 

 doubt extend to the remotest regions of the fixed stars, will operate in such a 

 manner as most probably to produce the following remarkable effects. 



Formation of nebula'. — Form 1. In the first place, since we have supposed 

 the stars to be of various sizes, it will frequently happen that a star, being con- 

 siderably larger than its neighbouring ones, will attract them more than they 

 will be attracted by others that are immediately around them ; by which means 



