Natchez 10th. Novr. 1805
An apology is due for the late appearance of my sketch of the Washita river, and I have not a good one to offer; I was not aware that upwards of twelve hundred Courses and distances would require so much time to reduce from time to measure in length & into latitude and departure; I had counted only upon a few days labor & therefore delayed too long to commence, and now it is not completed as I intended, which was to mark out the valley within which the Washita describes its meanders, and the alluvial Country below, subject to the inundation of the Missisippi; but I expect every instant the Post rider to call returning from Fort Adams, and I think it better to send it in its present state, than to delay another week, fearing already that it may arrive later than it was your desire to receive it.
I shall have the pleasure of writing you again in a few days & will then transmit a calculation for the Longitude of the Post of Washita from the Moon’s greatest altitude near the meridian; it agrees very near with a calculation from an observed eclipse of the moon some distance above the Washita; I place so much confidence in it, that I believe it to be my best observation for the Longitude of that place.
I have the honor to be with the greatest respect Your most Obedient Servant
DLC: Papers of Thomas Jefferson.