VOL. LXXIV.] PHILOSOPHICAL TRANSACTIONS. 6] 5 



direction of its length ab, or height cd, with all those in the intermediate situa- 

 tions, projected into the lucid circle acbd; while those in the sides mv, nw, will 

 be seen scattered over the remaining part of the heavens at mvnw. If the eye 

 were placed somewhere without the stratum, at no very great distance, the ap- 

 pearance of the stars within it would assume the form of one of the less circles 

 of the sphere, which would be more or less contracted to the distance of the eye; 

 and if this distance were exceedingly increased, the whole stratum might at last 

 be drawn together into a lucid spot of any shape, according to the position, 

 length, and height of the stratum. 



Let us now suppose that a branch, or smaller stratum, should run out from 

 the former, in a certain direction, and let it also be contained between two pa- 

 rallel planes extended indefinitely onwards, but so that the eye may be placed in 

 the great stratum somewhere before the separation, and not far from the place 

 where the strata are still united. Then will this 2d stratum not be projected 

 into a bright circle like the former, but will be seen as a lucid branch proceeding 

 from the first, and returning to it again at a certain distance less than a semi- 

 circle. Thus, in the same figure, the stars in the small stratum pq will be pro- 

 jected into a bright arch at prrp, which, after its separation from the circle cbd, 

 unites with it again at p. What has been instanced in parallel planes may easily 

 be applied to strata irregularly bounded, and running in various directions; for 

 their projections will of consequence vary according to the quantities of the va- 

 riations in the strata and the distance of the eye from the same. And thus any 

 kind of curvatures, as well as various different degrees of brightness, may be pro- 

 duced in the projections. 



From appearances then, as before observed, we may infer, that the sun is 

 most likely placed in one of the great strata of the fixed stars, and very pro- 

 bably not far from the place where some smaller stratum branches out from it. 

 Such a supposition will satisfactorily, and with great simplicity, account for all 

 the phenomena of the milky way, which, according to this hypothesis, is no 

 other than the appearance of the projection of the stars contained in this stratum 

 and its secondary branch. As a further inducement to look on the galaxy in this 

 point of view, let it be considered, that we can no longer doubt of its whitish 

 appearance arising from the mixed lustre of the numberless stars that compose 

 it. Now should we imagine it to be an irregular ring of stars, in the centre 

 nearly of which we must then suppose the sun to be placed, it will appear not a 

 little extraordinary, that the sun, being a fixed star like those which compose 

 this imagined ring, should just be in the centre of such a multitude of celestial 

 bodies, without any apparent reason for this singular distinction; whereas, on 

 our supposition, every star in this stratum, not very near the termination of its 

 length or height, will be so placed as also to have its own galaxy, with only 



