An exact chart of the River St. Laurence, from Fort Frontenac to the Island of Anticosti, shewing the soundings, rocks, shoals &c.

Published in "A General Atlas", with dedication to Jn. Montague, Earl of Sandwich. Dated 1771. This is the fourth state of five.
With five insets. A chart of the St. Lawrence River by the noted eighteenth century English cartographer Thomas Jefferys, Geographer to George III and the Prince of Wales.
Jefferys produced many important maps of America from 1751 until 1768, including this superior chart first issued in 1757. The main source for Jefferys was a map issued in 1702 based on a survey of the river by Jean Deshayes.
Deshayes map became the standard chart of the St. Lawrence until James Cook's surveys appeared in the second half of the century. Jefferys translated Deshayes' chart into English, and added an updated depiction of the river from Lake Ontario to Quebec based on J.B.B. D'Anville's 1755 map of Canada.
This is a sailing chart, complete with soundings, rhumb lines for navigation, written directions, and coastal profiles. The central part of the map shows the river from Anticosti Island to Quebec, and it includes a number of insets such as the one based on D'Anville's map and four others depicting important sections of the river with greater detail.
This reissue of the Jefferys map, which appeared in his "The American Atlas", was prompted by the growing tensions between the British government and its colonies, that generated an increasing demand for maps of North America.
The St. Lawrence River, with its importance for shipping to and from the prosperous Canadian settlements, was of particular interest to readers in London and elsewhere in the English speaking world.

Reference: Kershaw, Early Printed Maps of Canada II, 668.