13 
views have been held suggests a doubt whether either can 
rest on sure scientific grounds. The one thing which seems 
clear and certain is, that a structure like that of our globe 
with two main oceans extending almost unbroken from the 
south to the north pole, over three-fourths of the whole surface, 
is the arrangement most favourable to a mitigation of fierce 
extremes, and to fit our world for human habitation. At the 
same time, since the glacial epoch belongs to a stage of 
geology when the outlines of land and water were nearly the 
same as now, it is perfectly clear that no difference in their 
relative arrangement can serve to account for a much lower 
or a much warmer temperature than has obtained in the 
known histoi’ical period of the world. 
Y. — Varied Inclination Theory. 
22. Another theory of a more definite kind is advocated by 
Lieut. -Colonel Drayson, in his work entitled “ The Cause, 
Date and Duration of the Last Glacial Epoch of Geology.” 
He places the period of maximum glaciation 13,700 years 
before Christ, or 15,500 years ago. Such a view, if it were 
established, would plainly be much more reconcilable with the 
Bible chronology for the date of man’s appearance on the 
earth than the opinions just examined. But I believe that it 
rests on a fundamental mistake which it is not difficult to 
place in a clear light. Mr. Croll remarks on it as follows : — 
“ The theory is beset by a twofold objection. First, it can be shown from 
celestial mechanics that the variations in the obliquity must always have 
been so small that they could not affect the climatic condition of the globe. 
Secondly, even admitting that the obliquity could change to an indefinite 
extent, it can be shown that no increase or decrease, howeve j great, could 
possibly account for the glacial epoch, or a warm temperate condition in the 
polar regions.” 
23. This second objection, whether true or false, seems to 
me diametrically opposed to the reasoning of Mr. Croll in 
favour of his own hypothesis, when he would account for a 
glacial season by an increased excentricity, concurring with a 
northern winter solstice in aphelion. With regard to the total 
heat there is this slight difference, that a change of inclina- 
tion leaves it quite unaltered, but an increased excentricity 
causes a small increase. So far the second is less suited than 
the first to account for a glacial period. But with regard to 
total winter temperature, the operation of the two causes is 
precisely of the same kind, and the relative effect in the ratio 
