Philada. Decr. 16th. 1805
The Theodolite, which by advice from Mr. Freeman I purchased of Mr. Biggs, is carefully packed up, & put on board, a sloop for Georgetown—The bill of lading is here inclosed—The draft for 54 dolls was this day recd. & paid to Mr. Biggs—I have taken the liberty of enclosing, for Mr. Freeman, a Formula for solving a problem in practical Astronomy which I concieve may be of some use in his intended excursion; since it will enable him, by means of a very simple observation, which may be made & repeated at pleasure every clear night, to find the latitude of the place, the true hour of the night, & consequently the error of watch.—
I have the honour to be with the greatest esteem Your Most obedt. Servant
DLC: Papers of Thomas Jefferson.