In this letter, Jefferson refers to Churchman's plans to use magnetic variations to determine longitude. A method to determine longitude accurately had long eluded navigators, and Churchman, a land surveyor and cartographer, discovered what he thought was an ideal solution.
At the time of his writing, Jefferson was winding down his duties in Paris as Minister to France for the United States. In a June 8 letter, Churchman asked Jefferson to use his influence in helping him register his proposal with the Academie Royale des Sciences. The Academie also had received a request from Churchman. In his reply, Jefferson tells Churchman "your ideas were not conveyed so explicitly as to enable them to decide finally on their merit," and goes on to encourage the inventor, telling him, "I shall be happy that our country may have the honour of furnishing the old world what it has so long sought in vain."