262 SEE— THE NEW COSMOGONY. [April 2,. 



been detached by acceleration of rotation, as handed down by tradi- 

 tion from Laplace's original nebular hypothesis of 1796. 



2. As the planets and satellites could not have been thrown ot¥. 

 they must have been captured and added on from without, or else 

 have been formed from the agglomeration of fine dust right where 

 they now revolve. This latter alternative, however, is easily shown 

 to be impossible, owing to the feeble mutual gravitational attraction 

 of small masses of matter under the stronger tendencies to di.spersion 

 by tidal action, which always exist near large centres of attraction. 

 There remains therefore no possible mode of origin for the planets 

 and satellites save that of capture, or addition to the system from 

 without. 



3. When first captured the satellites must therefore have been 

 already of such considerable size that they were able to gather in, 

 and consolidate with their globes, numerous smaller masses revolv- 

 ing in the vortices about the planets. The collisions arising in this 

 process of the gathering in of smaller bodies by larger ones are 

 strikingly illustrated by the craters noticed in the face of the Moon, 

 which were formed by impact, the embedded satellites being in some 

 cases at least twenty miles in diameter. 



4. Thus while the satelHtes were all captured,^ and were orig- 

 inally further from their planets than they are at present, they have 

 grown larger in the course of ages as they revolved in the resisting 

 medium about tlie planets, just as the earth and primary planets are 

 still growing larger by the impact of meteorites against their sur- 

 faces, as they slowly approach the sun. The earth sweeps up daily 

 1,200,000,000 meteors, and the amount of this dust is calculated to 

 to form a layer a millimeter thick in a century. 



5. We know the satellites must have grown in mass since they 

 were captured, because they have been drawn nearer and nearer their 

 several planets, by increase of the central attraction, as in the cele- 

 brated problem of Gylden.^'' But if the mass of the sun has 

 increased, by the downfall of cosmical dust, so also must the mass 



^ Since this was written the capture of Satellites has been independently 

 confirmed by Professor E. W. Brown, in an important paper in the Monthly 

 Notices of the Royal Astronomical Society for March, 191 1, p. 453. 



'•'A. N., 2593. 



