The Evolution of Climates. — Manson. 177 
that these processes have constituted a system of climatic evo- 
lution, controlled by known laws. 
The cosmic laws of climatic evolution will be presented in 
the form of a series of postulates and corollaries. It is be- 
lieved that these will be generally admitted as true, at all 
events, anyone can readily satisfy himself regarding them. 
(i) Heat rays cannot pass through fogs and clouds, formed 
of the vapors of a fluid having the physical properties of 
water, except in a very greatly diminished intensity.* 
(2) A hot spheroid rotating in space and holding water and 
air (or fluids of similar properties) within the sphere of its 
control, gives off and receives heat subject to its passage 
through clouds. The spheroid must lose heat principally by 
the expansion of water into vapor and by radiation from the 
cool cuter surface of its cloud envelope, which envelope is 
maintained by the evaporation of water by the heat of the 
spheroid, and conserved by heat reaching it from exterior 
sources; during its existence it acts as a conservator of the 
heat of the spheroid. 
(3) That in the stages of cooling subsequent to the forma- 
tion of oceans, land surfaces must, by reason of their low spe- 
cific heat, cool faster than oceans; and that heat reaching the 
planetary surface by the circulation of meteoric or included 
water or by convection, or set free by denudations, faults and 
fractures, is principally taken up by water in its fluid and va- 
porous form, and conserved by water in the form of clouds. 
(4) The surface temperatures of such a spheroid must be 
practically independent of exterior sources of heat until the 
greater portion of the water surrounding it be reduced to its 
point of maximum density or converted into ice, and that prior 
to this stage of its climatic evolution, its surface temperatures 
are practically controlled by interior (or planetary) heat, and 
are practically independent of latitude; and are therefore inde- 
pendent of the temperature to which the outer surface of the 
cloud sphere may be exposed. The effect of variations in ex- 
terior heat being mainly to increase or decrease the duration 
of the Interior supph', and to expand or contract the sphere 
*Maury. Physical Geography of the Sea, 6th Ed., p. 212, et seq. 
Croll — Climate and Time, p. 60. Climate and Cosmology, p. 51. 
Geikie, J. — The Great Ice Age, pp. 800-801. 
