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 gushed up from the soil or rocks.  This track laid across highlands, which divide the confluent waters of the Missouri from those of the Mississippi.  Indians, wild beasts, starvation, thirst, were the dangers of the way.  This journey, which led into the vast and desolate parts of Arkansas, was replete with incidents and adventures of the highest interest.

While in Missouri, and after his return from this adventurous journey, he drew up a description of the mines, geology, and mineralogy of the country.  Conceiving a plan for the better management of the lead mines as a part of the public domain, he determined to visit Washington, to submit it to the government.  Packing up his collections of mineralogy and geology, he ordered them to the nearest point of embarkation on the Mississippi, and, getting on board a steamer at St. Genevieve, proceeded to New Orleans.  Thence he took shipping for New York, passing through the Straits of Florida, and reached his destination during the prevalence of the yellow fever in that city.  He improved the time of his quarantine at Staten Island by exploring its mineralogy and geology, where he experienced a kind and appreciating reception from the health officer, Dr. De Witt.