Geology and Natural story. 151 
of these cases being supposed to be as they now are. The final 
“probable” conclusions thence reached are: that “ the chief factor 
in changes of geological climate appears to have been the slow 
secular cooling of the sun;” that since life began on the globe, 
e earth’s interior heat can not be regarded as “the sole and 
immediate cause of change of climate;” that the carbonic acid 
and moisture of the atmosphere have added to the warmth of past 
climates, the former chiefly during Paleozoic and earlier times. 
e adds that the cold and precipitation of the Glacial era “ was 
robably due to atmospheric changes caused by a temporarily 
a rate of heat-radiation from the sun.” 
a note he introduces his calculations with regard to the total 
annual heat received at each point of the earth’s surface, and on 
the amount of the loss of that heat caused by radiation into space ; 
in which he finds that the whole amount of the sun’s heat received 
Is equivalent to that required to melt a layer of ice over the whole 
globe 80°5 feet thick, and that the part lost by radiation is equiv- 
alent to 28-5 feet of ice in thickness, leaving 51°5 feet, or more 
than 5-8ths of the whole, to be accounted for not as heat but as 
work, 
a 
lengths of the geological ages as measured by the maximum 
thickness of sedimentary deposits, and by the rate of progress 
in its cooling climate. But, in the calculation, the Cambrian or 
Primordial era (in which Trilobites, Brachiopods an orms were 
already in the seas) is united to the Azoic (Archzan), and thus 
it 1s made to antedate the epoch (of which he makes special use) 
when a mean Arctic temperature of 122° F. (that of the coagula- 
tion of albumen) was reached by the earth. 
Moreover the calculations make the time between the era of the 
uniformitarian Professor Haughton rightly opposes, since it appears 
to have no sufficient support in geological facts. But that of regu- 
lar —- in declining temperature is in equal disagreement 
ve been, and probably were, many maxima and minima in the 
course of the progress 
Am. Jour, penhcrea _—— Vou. XXI, No, 122.—Fxs., 1881. 
