"I had now had opportunities of knowing him intimately. Of courage undaunted; possessing a firmness and perseverance of purpose which nothing but impossibilities could divert from its direction; careful as a father of those committed to his charge, yet steady in the maintenance of order and discipline; intimate with the Indian character, customs, and principles; habituated to the hunting life; guarded, by exact observation of the vegetables and animals of his own country, against losing time in the description of objects already possessed; honest, disinterested, liberal, of sound understanding, and a fidelity to truth so scrupulous that whatever he should report would be as certain as if seen by ourselves--with all these qualifications, as if selected and implanted by Nature in one body for this express purpose, I could have no hesitation in confiding the enterprise to him. To fill up the measure desired, he wanted nothing but a greater familiarity with the technical language of the natural sciences, and readiness in the astronomical observations necessary for the geography of his route. To acquire these, he repaired immediately to Philadelphia, and placed himself under the tutorage of the distinguished professors of that place, who, with a zeal and emulation enkindled by an ardent devotion to science, communicated to him freely the information requisite for the purposes of the journey. While attending at Lancaster to the fabrication of the arms with which he chose that his men should be provided, he had the benefit of daily communication with Mr. Andrew Ellicott, whose experience in astronomical observation, and practice of it in the woods, enabled him to apprise Captain Lewis of the wants and difficulties he would encounter, and of the substitutes and resources afforded by a woodland and uninhabited country."