any
River from Western New York to the Ohio. He made Pittsburgh, Cincinnati,
and Louisville centres of observation. At the latter place he published
in the papers an account of the discovery of a body of the black oxide
of manganese, on the banks of the Great Sandy River of Kentucky, and
watched the return papers from the old Atlantic States, to see whether
notices of this kind would be copied and approved. Finding this test
favorable, he felt encouraged in his mineralogical researches. Having
descended the Ohio to its mouth one thousand miles, by its involutions
below Pittsburgh, and entered the _Mississippi_, he urged his way up
the strong and turbid channel of the latter, in barges, by slow stages
of five or six miles a day, to St. Louis. This slowness of travel gave
him an opportunity of exploring on foot the whole of the Missouri shore,
so noted, from early Spanish and French days, for its mines. After
visiting the mounds of Illinois, he recrossed the Mississippi into the
mineral district of Missouri. Making Potosi the centre of his survey and
the deposit of his collections, he executed a thorough examination of
that district, where he found some seventy mines scattered over a large
surface of the public domain, which yielded, at the utmost, by a very
desultory process, about three millions of pounds of lead annually.
Having explored this region very minutely, he wished to ascertain its
geological connection with the Ozark and other highland ranges, which
spread at the foot of the Rocky Mountains, and he planned an exploratory
expedition into that region. This bold and hazardous journey he
organized and commenced at Potosi early in the month of November, 1818,
and prosecuted it under many disadvantages during that fall and the
succeeding winter. Several expert and practiced woodsmen were to have
been of this party, but when the time for setting out came all but two
failed, under various excuses. One of these was finally obliged to turn
back from _Mine au Breton_ with a continued attack of fever and ague.
Ardent in the plan, and with a strong desire to extend the dominions of
science, he determined to push on with a single companion, and a single
pack-horse, which bore the necessary camp conveniences, and was led
alternately by each from day to day. A pocket compass guided their march
by day, and they often slept in vast caverns in limestone cliffs at
night. Gigantic springs of the purest crystaline water frequently g