I recieved on the 20th your letter of the 13th on the question what is an East and West line? which you say has been a subject of discussion in the newspapers. I presume however it must have been a mere question of definition, and that the parties have differed only in applying the same appellation to different things. the one defines an East and West line to be on a great circle of the earth, passing thro’ the point of departure, it’s nadir point and the center of the earth, it’s plane rectangular to that of the meridian of departure.   the other considers an E. & W. line to be on a small circle of the earth passing thro’ the point of departure, and preserving in every part of it’s course, it’s rectangularity with the axis of the earth, or, a line which, from the point of departure passes every meridian at a right angle. each party therefore defining the line he means, may be permitted to call it an East & West, one, or at least it becomes no longer a mathematical, but a philological question of the meaning of the words East and West. the last is what was meant probably by the E. & W. line in the treaty of Ghent. the same has been the understanding in running the numerous E. and W. lines which divide our different states. they have been run by observations of Latitude at very short intervals, writing the points of observation by short direct lines and thus constituting in fact part of a polygon of very short sides.

But, Sir, I do not pretend to be an arbiter of these learned questions. age has weaned me from such speculations, & rendered me as incompetent as unwilling to puzzle myself with them. your claim on me as a quondam neighbor has induced me to hazard thus much, not indeed for the newspapers, a vehicle to which I am never willingly committed, but to prove my attention to your wishes, and to convey to you the assurance of my respect.

Th: Jefferson