To Thomas Jefferson from William Lambert, 15 December 1804
From William Lambert
City of Washington, Decr. 15th: 1804.
Sir,
I have the honor to transmit to you some calculations I have lately made for determining the longitude and latitude of a place near the President’s house in this city, and have endeavored not only to render the work as accurate as I could from the elements assumed, but also to make it so plain that any person acquainted with the principles of astronomy cannot fail to understand it.—If you should, after examination, consider the statement and calculations submitted to you, worthy your acceptance, and you will be pleased to return them to me, (not being possessed of another transcript) I will furnish you with a revised copy, wherein the latitude and longitude now found will be used in the calculations to ensure a greater degree of precision in the result.
I have the honor to be, with perfect respect, Sir, Your most obedt: servant,
William Lambert.
RC (DLC); at foot of text: “The President of the United States.”; endorsed by TJ as received 17 Dec. and so recorded in SJL. Enclosure not found, but see below.
calculations I have lately made: in October, the assistant postmaster general, Abraham Bradley, Jr., with a clerk from his office, Seth Pease, and local schoolmaster David Wiley, made a series of astronomical observations “at a place near the President’s house, estimated to be one mile and 7/10ths N. 75° W. of the capitol in the city of Washington.” Using their data, which included observation of an occultation of Alcyone, the brightest star of the Pleiades, by the moon, Lambert performed calculations for multiple methods of finding longitude. He used the observers’ readings of the positions of four other stars to compute the latitude. Lambert had his revised computations printed in July 1805. He sent a version of the figures to TJ in September 1809, for consideration in fixing a prime meridian of the United States (Lambert, Calculations for Ascertaining the Latitude North of the Equator and the Longitude West of Greenwich Observatory, in England, of the Capitol, at the City of Washington, in the United States of America [Washington, D.C., 1805], 6-47; , 1:489-98; TJ to William Dunbar, 14 Mch. 1805; Lambert to TJ, 31 July 1805).