14 



THE BODIES OF SPACE. 



The nebular hypothesis, as it has been called, obtains 

 a remarkable support in what would at first seem to mili- 

 tate against it — the existence in our firmament of several 

 thousands of solar systems, in which there are more than 

 one sun. These are called double and triple stars. Some 

 double stars, upon which careful observations have been 

 made, are found to have a regular revolutionary motion 

 round each other in elipses. This kind of solar system 

 has also been observed in what appears to be its rudimen- 

 tal state, for there are examples of nebulous stars contain- 

 ing two and three nuclei in near association. At a cer- 

 tain point in the confluence of the matter of these nebu- 

 lous stars, they would all become involved in a common 

 revolutionary motion, linked inextricably with each other, 

 though it might be at sufficient distances to allow of each 

 distinct centre having afterwards its attendant planets. 

 We have seen that the law which causes rotation in the 

 single solar masses, is exactly the same which produces 

 the familiar phenomenon of a small whirlpool or dimple 

 in the surface of a stream. Such dimples are not always 

 single. Upon the face of a river where there are various 

 contending currents, it may often be observed that two or 

 more dimples are formed near each other with more or less 

 regularity. These fantastic eddies, which the musing poet 

 will sometimes watch abstractedly for an hour, little think- 

 ing of the law which produces and conects them, are an il- 

 lustration of the wonders of binary and ternary solar sys- 

 tems. 



The nebular hypothesis is, indeed, supported by so 

 many ascertained features of the celestial scenery, and so 

 many calculations of exact science, that it is impossible 

 for a candid mind to refrain from giving it a cordial re- 

 ception, if not to repose full reliance upon it, even with- 



time, of which it commonly forms the forty -fifth part" — showing, 

 we may suppose, that only some small elements of the question 

 had been overlooked by the calculator. The defect changes to an 

 excess in the different systems of the satellites, where it is propor- 

 tionally greater than in the planets, and unequal in the different 

 systems. " From the whole of these comparisons," says he, "I de- 

 duced the following general result : Supposing the mathematical 

 limit of the solar atmosphere successively extended to the regions 

 where the different planets are now found, the duration of the sun's 

 rotation was, at each of those epochs, sensibly equal to that of the 

 actual sidereal revolution of the corresponding planet ; and the 

 same is true for each planetary atmosphere in relation to the diffe* 

 rent satellites — Cours de Philosophie Positif. 



