4 Wilde, Origin of Cometary Bodies and Saturn's Rings. 



thousand feet in height, with their craters upwards of 

 forty miles in diameter, and are striking evidence of the 

 immense repulsive force which produced them. 



It has for a long time been considered on good 

 evidence that the planetoids between the orbits of Mars 

 and Jupiter (now numbering more than 600) are the 

 fragments of a large planet which had formerly revolved 

 in an orbit about the same distance from the sun as Ceres, 

 and had been shattered by some internal convulsion. 

 This hypothesis was put forward by Olbers the discoverer 

 of Pallas in 1802, and was made the subject of a memoir 

 by Lagrange in which he determined the explosive force 

 necessary to detach a fragment of a planet that would 

 cause it to describe the orbit of a comet. The nebulosities 

 of the dense atmospheres of some of these planetoids 

 concealing their disks indicate an incipient change of 

 planetary into cometary bodies. 



Attempts have been made during recent years to 

 discredit the explanation offered by Olbers of the origin 

 of the planetoids, by assuming that the annulus or 

 convolute of nebular substance failed to resolve itself into 

 a sphere, but was broken up into a number of small bodies. 



There is no inherent improbability in the idea of a 

 nebular convolution resolving itself into a number of 

 discrete spherical bodies as many of such are to be seen in 

 the convolutions of spiral nebulae, of which M.ioo Com;c 

 and M.74 Piscium are the most striking examples. The 

 convolutions of these nebulae contain nebular stars which 

 are involved symmetrically and follow the curvature of 

 the convolutions. M.ioo Comae is further interesting 

 from the fact of its showing elongated fissions of the 

 convolutions previous to their development into spherical 

 bodies. Such discrete bodies, revolving in a circular 

 orbit of the same diameter would, by their mutual 



