Sketch of Dr. John Locke. — Winchell. 347 
stones and soft sandstones are still lower in the bluffs, the 
river being on a sandstone. Another section extends from 
the Blue mounds to the Wisconsin river at Arena. 
The greater part of Dr. Locke's time and energy were spent, 
during this survey, on magnetical and barometrical observa- 
tions, this being more in keeping with the trend of his ambi- 
tion and taste, as well as his instructions. He presents a 
"magnetical chart" showing the lines of equal dip, crossing 
the lead region. There was a curious notion prevalent, shared 
by Owen as well as Locke, that the dip compass might be af- 
fected by the ore bodies of the lead region, and Dr. Owen 
calls particular attention to the probable action of "protoxide 
of iron" on "the needle. Locke, however, made a direct test 
as to the lead ore at Dubuque and found that the metallic 
vein exerted no peculiar magnetical influence. 
In 1847 Dr. Locke was again called to the examination of 
United States mineral lands. He received the appointment of 
first assistant, with instructions, in the early part of the sea- 
son of 1847, from Prof. C. T. Jackson, who had charge of the 
survey of the mineral lands in the northern part of Michigan. 
His field was from the mouth of the Chocolate river, where it 
joins lake Superior, to the little Bay de Noquet. This enter- 
prise, however, so far as Dr. Jackson's plans were concerned, 
resulted in failure. Personal ambition and jealousy united 
with political intrigue and partizan greed and effected the re- 
moval of Dr. Jackson, and the final completion of the survey 
by other hands. According to Dr. Jackson's statement in his 
final report,* he learned from the commissioner of the general 
land office that the "appropriation for the survey was endan- 
gered by certain representations which had been made to a 
member of Congress by persons opposed to it, or by persons 
who wished to supersede me, by limiting the appointment to 
a citizen of Michigan." He does not mention any individual 
by name, but it may be inferred from events which followed, 
connected with those which are patent in the report of Dr. 
Jackson, that the same gentleman who subsequently broke up 
the Michigan survey under Dr. A. Winchell, had no little influ- 
ence in effecting this revolution. Dr. Locke's reporl for L8 17. 
so far as it appears in the printed report of Dr. Jackson, con- 
journal of the Geological Survej for 1848. 
