544 DISSOLUTION. 



revolutions of planets and satellites; and the subsequent per- 

 formances of their revolutions in the predicted periods, have 

 verified the assumption. If, then, these remote bodies are 

 centres of gravitation, — if we infer that all other stars are 

 centres of gravitation, as we may fairly do — and if we draw 

 the unavoidable corollary, that the gravitative force which 

 so conspicuously affects stars that are near one another, 

 also affects remote stars; we must conclude that all the 

 members of our Sidereal System gravitate, individually and 

 collectively. 



But if these widely-dispersed moving masses mutually 

 gravitate, what must happen '. There appears but one ten- 

 able answer. They cannot preserve their present arrange- 

 ment: the irregular distribution of our Sidereal System 

 being such as to render even a temporary moving equi- 

 librium impossible. If the stars are centres of an attractive 

 force that varies inversely as the square of the distance, 

 there is no escape from the inference that the structure of 

 our galaxy is undergoing change, and must continue to 

 undergo change. 



Thus, in the absence of tenable alternatives, we are 

 brought to the positions: — 1, that the stars are in motion; 

 — 2, that they move in conformity with the laws of gravita- 

 tion; — 3, that, distributed as they are, they cannot move in 

 conformity with the law of gravitation, without under- 

 going re-arrangement. If now we ask the nature of this 

 re-arrangement, we find ourselves obliged to infer a pro- 

 gressive concentration. Stars at present dispersed, must 

 become locally aggregated; existing aggregations (except- 

 ing, perhaps, the globular clusters) must grow more dense ; 

 and aggregations must coalesce with one another. That 

 integration has been progressing throughout past eras, we 

 found to be indicated by the structure of the heavens, in 

 general and in detail; and of the extent to which it has in 

 some places already gone, remarkable instances are fur- 

 nished by the Magellanic clouds — two closely-packed ag- 



