228 Blake—Progress of Geological Surveys in Wisconsin. 
fiom a mass of such rocks beneath the secondary strata.’" 
(p. 63.) 
It is singular that Dr. Percival did not notice the absence of 
the northern or glacial drift over the area of the lead rogion. 
In Percival’s day the zinc ores had not been utilized, but he 
directed attention to their value for making not only spelter, 
but zinc oxide for paint,* and I am told that he was the first 
to induce the miners to make shipments of Smithsonite, “dry 
bone,” to the New Jersey Zine company at Newark. He thus 
hastened the utilization of the “dry-bone,” but Owen had already 
directed attention to its value. 
After the death of Percival and the reorganization of a sur¬ 
vey of the state under the direction of Prof. Jas. Hall, Prof. 
J. D. Whitney was selected to examine and report upon the 
lead region. 
Prof. Whitney at once recognized that the foremost unan¬ 
swered question in the minds of both the miners in the lead 
region and those who had written about the mineral deposits, 
was whether deep mining was likely to be productive; whether 
by sinking through the blue limestone [the Trenton Limestone] 
and other beds in the Lower Magnesian Limestone, new sources 
of ore might be found along the possible extension downwards 
of the crevices of the upper beds. This question, we may say, 
has not even yet been answered by actual trial, although it has 
been answered theoretically by Whitney and others in the nega¬ 
tive. We have seen that Percival gave the subject much atten¬ 
tion, and that the direction of his labors was toward solving 
the problem of the origin of the system of lead-bearing crevices, 
and of their relations to, or dependence for, their origin upon 
the faults, dislocations and breaks of the strata. 
Professor Whitney gave especial attention to this subject, 
and felt obliged to state that he differed in toto with Dr. Per¬ 
cival “ in the general conclusions which he drew from his obser¬ 
vations, especially in regard to the feasibility of deep mining 
in the lead region, the most important point, practically, to 
those interested in that district. ”f In the concluding pages of 
*First Report, p. 98. 
t Vol. I, Hall & Whitney’s Report, p. 84. 
