432 PHILOSOPHICAL TRANSACtlQNS. [ANNO I767. 



against the contrary, opinion being many million millions to one), that the stars 

 are really collected together in clusters in some places, where they form a kind 

 of systems, while in others there are either few or none of them, to 

 whatever cause this may be owing, whether to their mutual gravitation, or to 

 some other law or appointment of the Creator. And the natural conclusion 

 from hence is, that it is highly probable in particular, and next to a certainty in 

 general, that such double stars, &c. as appear to consist of 2 or more stars 

 placed near together, do really consist of stars placed near together, and 

 under the influence of some general law, whenever the probability is very great, 

 that there would not have been any such stars so near together, if all those that 

 are not less bright than themselves had been scattered at random through the 

 whole heavens. 



(i After what has been said, it will be natural to inquire, whether, if the stars 

 in general collected into systems, the sun does not likewise make one of some 

 system; and which are those, among the fixed stars, that belong to the same 

 system with himself. Now supposing the stars of one system to be in general, 

 and at a medium, of the same size and brightness with those of another, the 

 nvimberof stars of any one apparent magnitude, would bear the same proportion to 

 the number ofstarsofany other apparent magnitude, as they would do, in case all 

 the stars were scattered uniformly, and not in systems, provided the eye was 

 not placed in or near to one of those systems. And in this case, the brightness 

 decreasing as the square of the distance inversely, and the sphere, in which they 

 are included, increasing as the cube of the distance directly, the number of stars 

 of any one degree of brightness and upwards, should be as the cube of the square 

 root of that brightness. Supposing then the faintest of the 2000 brightest stars 

 to be less bright than the faintest of the first 70, in the proportion of about 30 

 to 1 (and I think the difference is not less than this) this number is smaller 

 than we might have expected, if the sun was not one of a system, in the propor- 

 tion of 2000 to about 12000 or 1 to 6. But Mr. M. lays the less stress on 

 this argument, for want of a more certain determination of the proportion of 

 light which we receive from the stars of different magnitudes. 



If, however, on a more accurate examination, it should be found, that the 

 quantity of light above assigned is not far from the truth, or, if the difference 

 of light should be greater than it is above supposed to be, (in which case the 

 argument will be still stronger) ; this will add a considerable degree of weight 

 to the other arguments drawn from analogy, in favour of the sun's making one 

 of a system of stars. 



If we would now inquire, which are probably those stars, which compose 

 part of the same system with the sun ; though it will not be possible to point 

 them out with certainty, yet there are some marks, by which we may, with great 

 probability include some, and exclude others, while the rest remain more 



