AMERICAN JOURNAL OF SCIENCE. 
[THIRD SERIES,] 
“Arr. XXIX.—On some controverted points in Geological 
Climatology; a reply to Professor Newcomb, Mr. Hill 
and others; by James Crouu, LL.D., F.R.S. 
NINETEEN years ago the theory was advanced that the Glacial 
epoch was the result of a combination of physical agents 
brought into operation by an increase in the eccentricity of 
the earth’s orbit. Few or no objections have been urged 
against what may be called the astronomical part of the 
theory, But the portions relating to these physical agencies 
time t 
combinations of physical agencies, it would not be dee ta 
if some of the original deductions in regard to them prov 
or alter them to any material extent, : : 
he only class of objections urged against the theory which 
now being pretty generally accepted. 
But it is in reference to the’ influence of aqueous vapor, fogs 
and clouds on the production and preservation of snow that 
the greatest diversity of opinion has prevailed. ‘The object of 
the present article is to examine at some length the princi 
UR. vatioee. Series, Vou. XXVI, No. 154.—Oor. 1883. 
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