It was sometimes my practice, when reading on a subject to make notes on a separate paper, and to stick the paper loosely into the book to which it related, as the most convenient place for finding it again. in one of the volumes of Bezout’s Cours de mathematiques, you will find such a note on the method of taking inaccessible heights and of reducing the planes of the triangles, when inclined, to the plane of the horison. I believe it is in Bezout’s course for the artillery, tho possibly in that for the Marine, for they are distinct works. it is in one or two leaves of 8vo size. proposing soon to undertake an operation of this kind on the ground, I should be very glad to recover that paper of notes, to refresh my memory on the subject. You would greatly oblige me by turning to the book and withdrawing the paper, which is loose, and inclosing it to me by return of the mail.—I am anxious to learn that they are printing the catalogue, being desirous to get a copy of it. it will need a most careful revisal of the proof sheets. Accept the tender of my esteem and respect.

Th: Jefferson