REVIEWS 767 
tics, at the beginning of the volume, relative to the year’s economic 
production. The report closes with a paper on the “ Properties and 
Tests of lowa Building Stones,” by H. Foster Bain, which cannot fail 
to prove of inestimable local value. 
Although the directing motive in the work of the survey has been 
toward economic and practical ends, this report contains, as have pre- 
ceding volumes, many discussions of general scientific interest. The 
treatment of strictly geological features, especially in their physio- 
graphic aspects, for thoroughness of preparation and clearness of pre- 
sentation will prove, beyond doubt, to be a source of great interest to 
the geologists of the country. 
The volume is admirably printed, and besides containing many 
new maps and diagrams, is judiciously illustrated by an expressive 
collection of photographs in half tone. Yo We 18. 
