"A small part of this work has already found its way to the public, being copies of a rough map laid before the North West Company of Canada.
"Of these regions the map makers have no doubt given the best delineation they could acquire; but of what was known, so little was founded on astronomical observations; and their being obliged to fill up the vacant space with what information they could procure, has led them into many errors.
"In this map now offered to the public, almost all the great rivers on the above part of the continent, on both sides the great mountains are traced to their sources; the sources of the Mississippi, and several other great rivers, and the shores of Lake Superior, have been examined and laid down by the author only.
"The position, extent and height of the hills and mountains, have engaged much of his attention; of which he has many landscapes. The last six years of his discoveries were on the west side of the mountains to the Pacific Ocean. Each Indian Nation's Territories, with their limits, and the places of the trading settlements will be marked out.
"The courses and distances, (taken when necessary to 100 yards,) with their calculations, etc., the astronomical observations, and rough maps on the scale of one inch to a mile, on which these maps are founded will be open to the inspection of the curious, while the work is publishing; and it will doubtless afford much speculation to the scientific, to find many of the great rivers of North America taking their rise in a small compass, and going off to the different seas like Radii from a centre.
"To render the map more general, and to give connection to all the parts, the author will avail himself of the Sea Coast of Hudson's Bay and the Pacific Ocean, etc., etc., as laid down by the latest navigators and travellers; whatever he has not personally examined himself, will be in a different colour, and the authority mentioned.
"Nothing less than an unremitting perseverance bordering on enthusiasm could have enabled him to have brought these maps to their present state; in early life he conceived the idea of this work, and Providence has given him to complete, amidst various dangers, all that one man could hope to perform.
"The map will be engraved in a neat, chaste manner, combining elegance and economy, on the scale of 3 inches to one degree of longitude and will form either a map or an atlas at the will of the subscriber.
"The arduous survey, on which the author is at present employed does not permit him to present the Public with a description of these Countries and the nations of aborigines. This he hopes to perform as soon as time permits.
"It is expected the geographical map will be ready for delivery to the subscribers by the latter end of the summer of 1820 at the latest.