RECENT COSMOGONIES 235 



larger than they are now, and have since been reduced in size 

 and rounded up by the secular action of the resisting medium 

 formerly pervading our system. As the planetary orbits were 

 once of vast extent, and have since contracted their dimensions, 

 it follows that the embryo planets once formed a connecting linE 

 with the present system of comets. In the course of immeasur- 

 able ages, the planetary system contracted its dimension enor- 

 mously, and at the same time eat out the interior portion of the 

 primordial solar nebula ; leaving about the sun and planets a hol- 

 low shell of nebulosity, from which, under the effects of certain 

 mutual perturbations, fragments drop down to visit us occa- 

 sionally. These are the comets, and this is why they come from 

 the shell or envelope at a great distance from the sun, an observed 

 fact which has puzzled astronomers and mathematicians for cen- 

 turies. 



In explanation of the axial rotations of the planets 

 he says : 



We may conceive that there is revolving about each planet 

 a vortex of cosmical dust, some of which falls against the surface 

 of the globe, and thereby accelerates its axial rotation. As the 

 predominant motion of the vortex is forward, the planet's rota- 

 tion naturally tends to become direct and the obliquity tends to 

 disappear. 



Doctor See's own appraisal of his theory can be 

 gathered from this, his concluding paragraph : 



The most remarkable fact about the capture theory of cos- 

 mical evolution is the harmony which it introduces among the 

 most diverse phenomena. This shows that it rests on true causes 

 and is approximately an ultimate truth, which may indeed be 

 modified by future discovery, but will never be radically changed. 

 It gives us a simple and natural conception of the processes by 

 which cosmical systems are formed and unites and harmonizes 

 all the known phenomena of the sidereal universe, so that, with 

 the exception of universal gravitation, it is believed to embody the 

 most ultimate law of the starry heavens. 



The Capture Theory Criticized 



Before proceeding to the more technical criticism of 

 Doctor See 's theory it may be well enough to get a clear 

 idea of the nature of this so-called nebula with which he 

 is conjuring. In considering Laplace 's nebula, we found 

 its density to be that of a cubical void 535 feet each way 

 charged with the equivalent of but a single cubic inch of 



