1912] The Ottawa Naturalist. 59 



rather by the particular case of collision in which the contact is 

 onlv grazing, or in which there is only a near approach. The 

 chances of these two latter conditions are of course much greater 

 than direct collision. In such cases the tidal strains induced, 

 added to the eruptive tendencies of highly heated gaseous 

 bodies, will cause masses of matter to burst out and recede to 

 great distances. They show mathematically that the tendency 

 will be to assume a two armed spiral form ; and the secondary 

 nuclei with the planetesimals, as the finer matter is called, 

 will revolve in elliptic orbits around the central sun. The 

 secondary nuclei at irregular intervals in the arms of the 

 spiral will graduallv attract the smaller finer matter in 

 these arms, and will, in doing so, tend to have their orbits 

 made more nearly circular and become the planets. Explanations 

 are given by this hypothesis of manv of the difficulties of 

 Laplace's theory, but only in a qualitative way, and, it seems to 

 me, it has yet to stand the test of the quantitative criticism 

 that was so long directed at the older hypothesis. 



More recently, about two years ago, a series of abstruse 

 papers dealing with the effect of a resisting medium in modifying 

 the orbits of planets and satellites has been published by T. J. J. 

 See but so far as I can learn the author's opinion of them is 

 much higher than that of any one else's. 



The question of the origin and development of our own 

 system, and of other systems as well, is still therefore in an un- 

 settled condition. On some things all are agreed, the chemical 

 unity of the cosmos, the nebular source of the w r hole system 

 and its development under the action of gravitation, the trans- 

 ference of work into heat and other dynamical laws form com- 

 mon starting grounds and are in reality of course the essence of 

 the whole matter. Whether the nebula was gaseous or pul- 

 verulent, planetary, spiral, or any other form, how it became 

 ordered and organized and how it collected into spheres, the 

 wisest are perplexed to decide. There seems to be no question 

 that, while the Laplacian hpyothesis contains the germ of the 

 truth, the process of development was by no means so simple 

 and direct as was therein stated, and that we do not yet know 

 the precise mode of development of the solar system. 



And yet, behind and above and before all this development 

 and evolution we have been talking about, even the most 

 sceptical must admit the presence of a Supreme Pow T er, a Power 

 which must have created in the first place, and a Wisdom and 

 Beneficence which so ordered and arranged the development 

 of Creation as to make it the result of the action of natural laws. 

 And yet not less wonderful is the Love, which created the human 

 mind and gave to it the power, though inhabiting for only a 



