Farley near Bristol
Bucks county Pennsylvania, October 10th 1805
As President of the Philosophycal Society, I take the Liberty of laying before you a method of ascertaining the Longitude with the same precision that at present obtains in fixing the latitude, which is Simply this. in Reflecting upon what happens to all navigator who sail round the world, in one direction they loose a day, in the other they gain one, it occured to me, that it might be, that this circumstance had Something to doe with perplexing their calculations, and by following a line around the globe, there are no points further distant from each than 180. degrees, and yet we find they have treated the Globe as they would treat a level plain, in carrying the longitude all round, which I believe to be an error—and therefore conceive the Idea of stoping, at midway and fixing two points distant from each other 180 degrees—for instance I will call Philadelphia my first meridian, and this meridian cuts the Equator at 75.dr 20m west from London, I count 90. degrees on the Equator westward which brings me to the westren Ocean, and here I fix my westren pole. I return, and count 90. degrees eastward, and this brings me to the Westren Part of the contenant of africa. here I fix my Eastren pole. I then draw a line which is to cross the Equator at right angles, on my first meridian, and pass through the center of the north and south poles—and so devide the Earth into an eastren, and a westren hemisphere. the 24 meridians, I reduce to 12. alotting six to each hemisphere—each of these meridians contain 15 degrees and these meridians run parrillell with the Horisontal Equator which devides the globe into an eastren and westren hemisphere, and in receding from this line toward the eastren or westren poles—the latitude decreases in the same Ratios as we find the longitude dose in approaching the northren or Southren poles—a Globe constructed upon this plan will give a day of twelve hours — without being involved with the diurnal revolution of the Earth, and the quadrant will determine longitud and latitude equaily.
Your Humble Servant
ViW: Jefferson Papers, Tucker-Coleman Collection.