128 Transactions.— Miscellaneous. 
Comets and Solar System. 
It is almost certain that the initially irregular shape of the two coalesced 
pieces would cause many smaller masses to fly off into space, producing 
possible visitants to other worlds, but in most cases the heat would be 
sufficient to cause all these masses to be converted into gas. 
When two bodies of different size attract each other, the velocity 
acquired by the smaller body will be greater than that of the larger one (as 
an apple falling to the earth does not give the earth the same velocity as 
the apple itself acquires). With unequal bodies therefore, when collision 
occurs, the larger piece. will have a smaller velocity than the smaller, hence 
there will be two orders of fragments. First, from the small piece, the high 
velocity of which may make comets and shooting stars of them. 
Planets. 
Secondly, the fragments of the larger piece, whose small velocity may 
not take these bodies away from effective attraction, and they may thus 
become planets. 
But the large mass of our sun shows that if the planets of our system 
have been formed in this way, one of two things must have occurred, either 
the original proper motion of the bodies must have been very much greater 
than the average is at present, or the bodies themselves must have been 
very large, so that even at impact the centres were a long distance from 
each other. There is, however, another reason why at impact the centres 
may have been at a distance from each other—namely, the great distortion 
of the bodies which must take place immediately before impact, in conse- 
quence of their mutual attraction. tis impossible to give even an approxi- 
mate idea of how much this may influence the result. Generally, it is easy 
to see that the problems offered by partial impact are of extreme difficulty, 
the data being of necessity of infinite variety. 
It is shown further on, that there is another partial impact hypothesis 
which may possibly explain the origin of our system. 
All the following remarks apply equally to that hypothesis :— 
- At first the orbits of these bodies would be extraordinarily eccentric ; 
on passing away on this firsí journey they would be in advance of the 
expeled gas, but would meet it on returning. This would tend to 
neuiralise the force of attraction, and the orbit would become much more 
circular. Again, the passage of the planet through the gas would retard it. 
And lastly, on each of its orbits the attraction of gravitation would be 
greater on its outward journey than on its return, in consequence of the 
expelled matter passing outside its orbit into space. This fact would both 
tend to render the orbit more circular, and also tend to neutralise the action 
of the gaseous resistance in causing the body to approach the sun. It 
