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.