60 THE POPULAR SCIENCE MONTHLY. 



them, (4) shows that certain of them are its necessary consequences, 

 would probably be right, even though it had not been yet shown that 

 among all other possible theories there is not one which is not directly 

 contradicted by some known facts. As, however, the general theory 

 of the ejection of all cometic and meteoric bodies from orbs suns of 

 all orders, giant planets, terrestrial planets, planetoids, and moons is 

 as strongly supported by such negative evidence as it is by direct 

 positive evidence, I venture to say that a case not easily shaken has 

 been made out in its favor. No one, so far as I know, has yet indi- 

 cated any objection against the theory in the generalized form in which 

 alone I have ever advanced it. Objections have been urged against 

 it in the form in which it has been supposed that I have maintained 

 it. It has been very clearly shown that meteors can not come to the 

 earth from the sun unless they strike the earth on their first course 

 out from the central orb ; it has been proved that a considerable pro- 

 portion of the meteoric and cometic systems known can not have had 

 their origin either in our sun or in any of his fellow-suns, the stars ; 

 it has been urged as effectively that the giant planets can not eject 

 comets or meteors ; and it has been shown clearly that our earth can 

 not, in any stage of which geology has traced the records, have ejected 

 bodies which could thenceforth travel in interplanetary space as meteors 

 or meteor-fligbts. But, in these objections against specific theories of 

 the possible origin of comets and meteors, we may find some of the 

 strongest, if not the very strongest, arguments for that general theory 

 to which each specific theory points, so soon as we notice that the 

 arguments supporting each specific theory are such as decline to be 

 limited to that theory alone. 



In fine, as I suggested at the outset, if we apply to the several 

 specific theories of comets and meteors the general principles laid 

 down by Professor Newton, we find ourselves led irresistibly to that 

 general theory which I have sketched above, and presented with more 

 elaboration of detail elsewhere. 



T 



INFLUENCE OF SNOW-MASSES ON CLIMATE. 



By M. A. J. WOE1KOFF. 



HE masses of snow and ice known as glaciers, which are found 

 -a- upon high mountains, have been the object of many studies ; and 

 it is a matter to be wondered at that the same has not been the case 

 with the immense beds of snow that every winter cover parts of Eu- 

 rope, Asia, and America, to disappear in the following spring. It has 

 perhaps been thought that the latter have less influence upon climate 

 in general than upon other more special phenomena. But the observa- 

 tions that follow will tend to show that this influence exists and the 

 subject is one well worthy to be studied. 



