1 64 Transactio7is. — Miscellaneous. 



space — any mass escaping during, or immediately after, the impact ■would 

 be exposed to a much higher attraction on escaping than on the return, 

 because, on leaving them, the three bodies would be exercizing attraction 

 upon the body ; but, on the return journey, there would be only one body. 

 Thus its aphelion may not be near so distant as that of a body that had 

 only the central mass acting on it in its outward journey ; but this will not 

 necessarily affect the eccentricity, but may do so in certain cases. 



Aet. XIV. — The Origin of the Solar System. 

 By Professor A. W. Bickerton. 

 [Read before the Philosophical Institute of Canterbury 5tli August, 1880.] 

 The order displayed in the structure of the Solar System strongly suggests 

 the idea that it must have originated in some single event. Laplace has 

 calculated that the probability of such a system having originated in a 

 common cause, is not less than four millions to one. It is evident, there- 

 fore, that its origin is a legitimate subject for scientific speculation, and in 

 order to account for the peculiarities of the motions of the planets and 

 satellites, Laplace himself suggested the now well known hypothesis of the 

 release of nebular rings and their subsequent coalescence. This theory 

 has found many supporters, but when it is examined in the light of the 

 doctrine of the conservation of energy and the dynamical theory of gases, 

 so many difficulties present themselves as to throw great doubt upon it, in 

 fact, as Denison says, it has been so little accepted by English mathema- 

 ticians that it has scarcely been discussed, and Faye has recently given his 

 opinion that it must be given up. A modification of the theory is offered 

 in Newcombe's "Astronomy," — it is that the release of rings commenced on 

 the inside. 



I hope to examine a number of the difficulties of these theories in a future 

 paper. Proctor has discussed the probability of the system having been formed 

 by the coalescence of an immense number of meteorites, and to this hypo- 

 thesis there appear to be fewer objections than to the other two. In fact it is 

 highly probable that such an action has aided materially in giving symmetry 

 to the system. But as the sole agent in the formation of the solar system 

 these suggestions have two great objections : — the extreme slowness of the 

 sun's present rotation ; and the irregularities in the system, such as the 

 eccentricity of the orbits, the inclinations of the axes and orbital planes, and 

 retrograde motions. It cannot therefore be considered that a satisfactory 

 solution of the problem has been given, and it is probable from its extreme 



