VOL. LXXIX.] PHILOSOPHICAL TRANSACTIONS. f Ql 



quainted with attraction, this gradual condensation would point out a central 

 power, by the remarkable disposition of the stars tending towards a centre. In 

 consequence of this visible accumulation, whether it may be owing to attraction 

 only, or whether other powers may assist in the formation, we ought not to hesi- 

 tate in ascribing the effect to such as are central ; no phenomena being more 

 decisive in that particular, than those of which I am treating. 



I am fully aware of the consequences I shall draw on myself in but men- 

 tioning other powers that might contribute to the formation of clusters. A 

 mere hint of this kind, it will be expected, ought not to be given without suffi- 

 cient foundation ; but let it suffice at present to remark that my arguments 

 cannot be affected by my terms : whether I am right to use the plural number, 

 — central powers, —or whether I ought only to say, — the known central force of 

 gravity, — my conclusions will be equally valid. I will however add, that the idea 

 of other central powers being concerned in the construction of the sidereal hea- 

 vens, is not one that has only lately occurred to me. Long ago I have enter- 

 tained a certain theory of diversified central powers of attractions and repulsions; 

 an exposition of which I have even delivered in the years 1 780 and 1781, to the 

 Philosophical Society then existing at Bath, in several mathematical papers on 

 that subject. I shall however set aside an explanation of this theory, which 

 would not only exceed the intended limits of this paper, but is moreover not re- 

 quired for what remains at present to be added, and therefore may be given some 

 other time, when I can enter more fully into the subject of the interior con- 

 struction of sidereal systems. To return, then, to the case immediately under 

 our present consideration, it will be sufficient that 1 have abundantly proved 

 that the formation of round clusters of stars and nebulae is either owing to cen- 

 tral powers, or at least to one such force as refers to a centre. 



I shall now extend the weight of my argument, by taking in likewise every 

 cluster of stars or nebula that shows a gradual condensation, or increasing 

 brightness, towards a centre or certain point ; whether the outward shape of 

 such clusters or nebulae be round, extended, or of any other given form. What 

 has been said with regard to the doctrine of chance, will of course apply to 

 every cluster, and more especially to the extended and irregular shaped ones, on 

 account of their greater size : it is among these that we find the largest assem- 

 blages of stars, and most diffusive nebulosities ; and therefore the odds against 

 such assemblages happening without some particular power to gather them, in- 

 crease exceedingly with the number of the stars that are taken together. But if 

 the gradual accumulation either of stars or increasing brightness has before been 

 admitted as a direction to the seat of power, the same effect will equally point 

 out the same cause in the cases now under consideration. There are besides 



