542 Transactions. — Miscellaneous. 



in what was the rarest part of space ; so that an action is 

 constantly going on tending to balance the distribution of 

 matter in space, whilst the action of gravitation is as con- 

 stantly tending to unequal distribution. 



It may be asked, How can matter ever escape such a 

 universe again? Two or three methods suggest themselves, 

 and there are probably others. Firstly, contact with hot 

 bodies having no atmosphere would give the gaseous matter 

 an escaping velocity. Secondly, any bodies coming into impact 

 would tend to lose their hydrogen through the phenomena 

 known as "selective escape." Thirdly, three bodies passing 

 near each other may give one of them an escaping velocity at 

 the expense of the other two. Universes formed in this way 

 by aggregation in the rare parts of space may be called uni- 

 verses of the first order ; whilst universes such as the one of 

 which our solar system forms a part — universes obviously 

 made up of the coalescence of two impacting universes — may 

 be called universes of the second order. If a universe formed 

 by the coalescence of two similar universes necessarily con- 

 tained more matter than one of the original universes, when 

 the coalesced universe had condensed to its size a process of 

 aggregation would be going on in the cosmos that would ulti- 

 mately lead to the increase of the masses of universes, and 

 the cosmic process would not be strictly rhythmic. 



I have already suggested three agencies, in universes of the 

 first order, by which matter may pass out of universes. In 

 addition to these it can be shown that, during the ages of 

 coalescence and subsequent expansion of the system, there 

 are many agencies that will send matter out of the system. 



Taken altogether there seems reason to suppose that some- 

 times the collision of universes may make three of two, some- 

 times make one of less mass than either of the two original 

 universes, and sometimes one of greater mass than either. 

 But the agencies are of such complexity and variety that they 

 would simply overload this statement of the possibility of an 

 immortal cosmos. The most important agency to consider is 

 the approach of three bodies. This may gradually use up 

 the chief energy of a system in sending bodies out of the 

 system. As is well known, whenever three bodies pass near 

 each other, one at least has its velocity increased at the ex- 

 pense of the other two. It may so happen amongst the mem- 

 bers of a system that one has its velocity so increased as to 

 actually escape the attractive power of the system itself, and 

 become a free wanderer, as 1830 Groombridge is believed to be 

 in our universe. No matter how rare an event this may be ; 

 only give time enough, and most of the energy of motion 

 must be used up in thus causing the escape of bodies. For 

 we must remember, if once, in a thousand chance approaches, 



