1885.] of the Appalachian Mountains. 265 
The mathematical solution of geological problems such as 
that now under consideration is far from being satisfactory to 
geologists. Without in the least undervaluing the labors of the 
many eminent mathematicians who have taken the subject in 
hand, I may plainly assert that the conditions are yet too little 
known to enable them to apply their processes with complete 
success. The mill grinds out its meal according to the nature of 
the grist supplied, but cannot change its quality. So the math- 
ematical engine, of whatever kind, works out its conclusions 
from the premises given. If these are full and true the results 
cannot be false, But if these are insufficient and half unknown, 
or if any of them are much limited and modified, the results are 
to an uncertain extent invalidated. This is the case with almost 
all investigations dealing with the condition of the earth’s inte- 
rior. In order to bring them within the grasp of mathematical 
formulas the data of the problem are narrowed down or altered 
to so great a degree that the conclusion, though true for these, is 
false for the actual data. A logical fallacy lurks in the argument. 
The reasoning deals with an imaginary earth possessing certain 
comparatively simple characters. The conclusion when obtained 
is applied to the real earth, whose characters are much more 
complicated. The confusion lies in the employment of the term 
“earth” in two different senses—a logical fallacy of the first mag- 
nitude, and one whose insinuation into any geological problem 
must be avoided with the utmost care if conclusions of value are 
anticipated, 
Hence without any expressed or implied disrespect to the 
mathematician, the geologist may receive his arguments on geo- 
Dr. T. Sterry Hunt has recently, in the discussion of a different subject, put forward 
some views which deserve mention in this connection, and may not be without bear- 
ing upon the matter in hand, He has dwelt strongly on the universally crumpled 
ble region. Much less is : t 
ranges of metamorphic strata than of the Appalachian mountains. What is sup- 
posable at one stage need not, however, be absurd at another, and I am glad to be 
able to quote Dr, Hunt’s words, even if only in a slight degree conveying 4 sugges- 
tion similar to my own. 
