loo TJie Americaii Geologist. August, 189:) 
world through the labors and researches of the eminent geolo- 
gist and physicist, Dr. James Croll, in his various articles in 
leading scientific magazines, and lastly, in his notable contribu- 
tions to the subject under discussion, "Climate and Time," 
and "Climate and Cosmology." 
The scope of study and the ingenuity of presentation of 
Dr. Croll's views are models — yet scientists cannot accept his 
conclusions. 
Dr. Geo. F. Becker has presented a mathematical discus- 
sion of the physics of Dr. Croll's theory and presents the fol- 
lowing opinion. "It seems to me, then, that the period of tht 
greatest eccentricity would be most unfavorable to glaciation, 
the snow-fall being the smallest, and the summer rainfall the 
largest which can occur with the present obliquity."* . 
Later in the same paper Dr. Becker leans somewhat to- 
wards the views of Dr. Wallace. "I feel compelled to assert 
that the combination of lozv eccentricity mid high obliquity 
will promote the accumulation of glacial ice in high latitudes 
more than any other set of circumstances pertaining to the 
earth's orbit. It seems to me that the glacial period may be 
due to these conditions in combination with a favorable 
disposition of land and water. "t 
Dr. Jas. Geikie, after his exhaustive review of the principal 
hypotheses which have been brought forward, says: 
"The primary cause of these remarkable changes is thus an 
extremely perplexing question, and it must be confessed that 
a complete solution of the problem has not been found. Croll's 
theory has undoubtedly thrown a flood of light upon our dif- 
ficulties and it may be that some modification of his views will 
eventually clear up the mystery. But for the present, we must 
be content to work and wait." J 
This view is also applicable to the views of Dr. Wallace. 
Dr. T. G. Bonney, in an interesting discussion of this sub- 
ject, remarks: 
"The extension of the glaciers on Mt. Kenya, 19,500 feet, 
is specially interesting, because its position (almost on the 
*Certain Astronomical Conditions Favorable to Glaciation. Am. 
Jour. Sci., Vol. XLVIII (1894), p. 106. 
fib. p. 107. 
JThe Great Ice Age, 3rd Edition, p. 816. 
