227 
The Iron Ores of the Lake Superior Region. 
recognition on the part of practical mining men of these principles will 
save large sums of money annually spent in unscientific prospecting, 
and, as they have already done in certain cases, will undoubtedly lead to 
the discovery of additional ore-bodies. 
U. S. Geological Survey, 
Lake Superior Division, 
Madison, Wis., March 7,1892. 
