David Thompson joined the
Hudson’s Bay Company in 1784 as an apprentice. He developed his skills
as a surveyor and map maker, but the company was more interested in
procuring furs from the Indians and ordered him to stop his surveying
work. In 1797 he joined the North West Company and during the next
sixteen years he traveled through more than 55,000 miles from the
Missouri River in the south to Hudson Bay in the north, the
Mississippi River on the east and the Pacific Ocean on the west.
To determine the longitude, in the absence of accurate
chronometers, Thompson observed the eclipse of Jupiter’s moons, or by
measuring the angle of the moon against two stars. With “peg points”
determined in this way he then completed the survey to fill out the
In 1813 he created a chart approximately ten feet by
six and a half feet tall. The original of the Map of the North-West
Territory now hangs at the Archives of Ontario, Canada. Thompson
erroneously included the “Caledonia River” between the Fraser and
Columbia Rivers on his map. A year later he corrected the error.
However, others who pirated his work continued to include the
fictitious river form many more years.
From 1816 to 1827 Thompson served as chief
astronomer and surveyor for the British team of the International
Boundary Commission. After he resigned from the Boundary Commission he
again turned to surveying the Muskoka Lake area in southern Ontario.
The map on the stamp is not Thompson's Map of the
North West Territory of the Province of Canada. It is rather a
fictional map of the general area.
For further information about David
Thompson see Stephen R. Brown, The Astonishing Astronomer of the
Northwest," Mercator's World 6:2(2001)42-49.