1883.] Recent Literature. 853 
atlas sheets. A noticeable feature of the method of illustration 
is that all facts which are very numerous are boldly separated 
from the hypothetical deductions, so that Mr. Ashburner and his 
assistants give every one the means of verifying, modifying, or 
disproving their conclusions. This renders the work of more 
prominent and practical value than much of the geological map- 
ping which is published, and in addition inspires the confidence 
of practical men. 
The plan of representing geological structure of sedimentary 
strata by underground contours, although not novel in itself, since 
it has been employed extensively by Lesley in America in private 
surveys, and Lyman in Japan in government surveys, yet Ash- 
burner deserves the credit of perfecting the method and of prac- 
tically applying it to the exhibition of the complicated structure 
of the anthracite coal beds, which have every conceivable angle 
of dip from o° of a horizontal position to 35° overturned from a 
vertical position. With all this bold flexuring not a single break 
or fault in the strata of the Panther Creek basin is shown in any 
of the cross-sections, although the mine sheets show several of 
inconsiderable extent, being all, however, under ten feet. This is 
a remarkable fact when one recalls the numerous faults found in the 
