enterprise in traversing vast regions, awakened a corresponding spirit;
and the publication of his narratives had the effect to popularize the
subject of mineralogy and geology throughout the country.

In 1821, he executed a very extensive journey through the Miami of the
Lakes and the River Wabash, tracing those streams minutely to the
entrance of the latter into the Ohio River. He then proceeded to explore
the Oshawanoe Mountains, near Cave-in-Rock, with their deposits of the
fluate of lime, galena, and other mineral treasures. From this range he
crossed over the grand prairies of the Illinois to St. Louis, revisited
the mineral district of Potosi, and ascended the Illinois River and its
north-west fork, the _Des Plaines_, to Chicago, where a large body of
Indians were congregated to confer on the cession of their lands. At
these important conferences, he occupied the position of secretary. He
published an account of the incidents of this exploratory journey, under
the title of _Travels in the Central Portions of the Mississippi
Valley_. He found, in passing up the river _Des Plaines_, a remarkably
well characterized specimen of a fossil tree, completely converted to
stone, of which he prepared a descriptive memoir, which had the effect
further to direct the public mind to geological phenomena.

We are not prepared to pursue minutely these first steps of his
energetic course in the early investigation of our natural history and
geography. In 1822, while the lead-mine problem was under advisement at
Washington, he was appointed by Mr. Monroe to the semi-diplomatic
position of Agent for Indian Affairs on the North-west Frontiers. This
opened a new field of inquiry, and, while it opposed no bar to the
pursuits of natural science, it presented a broad area of historical and
ethnological research. On this he entered with great ardor, and an event
of generally controlling influence on human pursuits occurred to enlarge