City of Washington, July 15th: 1818.
I have the honor to inclose herewith, two printed copies of abstracts of calculations relative to the longitude of the Capitol, in this City from Greenwich Observatory, in England.—These calculations were entered into, and completed, to lay a foundation for the establishment of a first meridian for the United States of America at the Seat of their government, according to the original plan of Andrew Ellicott, Esq; in which the longitude of the Capitol is marked 0°.0’.
It is unnecessary to remind you, that any place on the surface of the Earth may be intended as a first meridian for the kingdom or Country in which such place may be situated; but in order to establish it, the distance between it and some other known meridian, measured or estimated on a parallel to the equator, must be obtained with great accuracy. Occultations of fixed Stars by the Moon, and solar eclipses, are acknowledged to be the best means hitherto devised for the attainment of that object; and altho’ the result contained in the abstracts, may not be strictly correct, for want of corresponding observations at Greenwich, yet it is believed to be a near approximation to the truth.
The American Philosophical Society at Philadelphia, to which a manuscript copy had been transmitted about twelve months since, have done me the favor of publishing it, in full, in the last volume of their transactions.
You will please to accept one copy for your own use, and to present the other to such seminary of learning, or Scientific person in your Section of the Union, as you may choose, except Mr. Bowditch, of Salem, to whom a copy has been sent.
An answer, containing your opinion of the plan, and the calculations founded upon it, will be highly acceptable.
I have the honor to be, / with great respect, / Your most Obedt. servant,
It may not be improper to observe, that the work was originally undertaken with the approbation of Mr. Jefferson, and bishop Madison, late president of William & Mary College, Virginia.
MHi: Adams Papers.