9 



must accumulate upon these areas until the oceans 

 cease to give off sufficient vapor to shield the earth from 

 solar energy. That these accumulations of snow must 

 reach their maxima along belts of maximum precipita- 

 tion, and must be independent of latitude. 



(7) That upon the chilling of the oceans, the sup- 

 ply of vapor maintaining the cloud envelope is cut off, 

 and the atmosphere deprived of the greater portion of 

 its heat intercepting power; and that heat rays from 

 exterior sources then reach the planetary surface in 

 sufficient quantity to dominate its climates. That a 

 new distribution of temperatures is thereby inaugurated 

 dependent principally upon latitude or exposure to exte- 

 rior sources, and modified by elevation and local causes. 



(8) That solar rays by contact with the planetary 

 surface are partly converted into dark or obscure rays 

 and are trapped,* or are selectively absorbed.! That a 

 gradual accession of heat must be thereby inaugurated, 

 resulting in the removal of glacial conditions, and that 

 such removal of glacial conditions must be on lines 

 determined by the degree of exposure to solar energy, 

 and by the susceptibility of the different portions of the 

 globe to be influenced by such exposure. That these 

 new conditions must inaugurate a new distribution of 

 temperatures ranged in zones and subject to solar control. 



The necessary corollaries of these postulates are: 

 (a) That a planet having water and air within the 

 sphere of its control, and which has not yet exhausted 

 its internal heat, must be densely shrouded in clouds 

 whose outer surface presents a high albedo. 



*Tyndall— Proc. Royal Soc, Vol. XIII, p. 160 Phil. Trans., Vol. 152, 

 p. 95. Archives des Sciences, torn. V., p. 293. 



tLangley — Investigations on the A.ction of the Atmosphere on Solar Ra- 

 diation. Mem. Nat. Academy of Sciences, 1885-7. 



Buff — Archives des Sciences, torn. LVII, p. 293. 



