668 Wey (Go (CLAANIM SS PISSLION. 
in such an extremely distributive form would be exceedingly 
low. It would seem, therefore, that unless the argument from 
molecular velocities is radically and grievously at fault the 
hypothesis of a gaseous earth-moon ring is untenable unless a 
degree of tenuity be assumed which separates the molecules 
beyond the limits of effective kinetic relations. Inthis case the 
argument from rapid cooling becomes peculiarly strong and 
seems to leave no alternative but the conversion of the refractory 
matter of the ring into the discrete solid condition. 
Impressed by these considerations and following what seem 
to be the legitimate implications of molecular studies, I have vent- 
ured for myself to place the atmospheric inferences from the 
supposed gaseous and molten conditions of the primitive earth 
in the list of uncertain deductions and to add an alternative 
hypothesis to my working list. 
But occasion for doubt concerning an early molten earth and 
its vast atmosphere is not limited to this line of approach. On 
other grounds we cannot fail to recognize that some form of the 
meteoroidal hypotheses of the origin of the earth is entitled to 
be reckoned among the possibilities. Whether an accretion of 
meteoroidal matter would give rise to a molten earth or not 
would depend upon the rapidity and violence of the infall. If 
the intervals between falls were sufficient the heat would be lost 
concurrently. A relatively cold earth is theoretically as possible 
as a hot one until it is shown that the aggregation must be rapid. 
Even following the general line of the nebular hypothesis a cold 
earth is hypothetically possible. We have found reason for 
thinking that the earth-moon ring, if formed, would probably 
become cooled to discrete solid particles while still in the ring 
form. Now it does not appear that there are any conditions 
inherent in such a ring that tend toward sudden concentration 
into a spheroidal body. Quite on the other hand, the problem 
presented by such a ring is to find agencies which will lead to 
its concentration at all. Just how the concentration would take 
place is an unsolved question.’ But two things seem certain; first, 
*I have ventured to speculate a little upon this, though beyond the province of a 
