The discoveries made in the North West parts of Hudson's Bay by Cap't Smith in 1746 & 1747

This is one of three maps engraved by Thomas Jefferys which accompanied The Great Probability of a Northwest Passage: Deduced from Observations on the Letter of Admiral De Fonte, by Theodorus Swaine Drage published in London in 1768, who had sailed on the voyage as a clerk. The map was published following the 1746-7 voyage sponsored by the schemer and politician Arthur Dobbs and led by Captains Francis Smith and William Moor.