Thomas Jefferson Papers

William Lambert to Thomas Jefferson, 9 January 1812

From William Lambert

City of Washington, January 9th 1812.


The inclosed abstract of calculation relative to the longitude of Monticello from Greenwich by the apparent times of internal contacts of Sun and Moon on the 17th of September last, will, it is hoped, be accepted by you as an accurate result, admitting the data to be correctly stated. Having in a former communication, given rules for ascertaining the altitude and longitude of the nonagesimal, Moon’s parallaxes, &c. I did not suppose it necessary to repeat the operation in this; permit me to request, that you will send a copy of this abstract, if approved, to bishop Madison, at Williamsburg.

You will find that by the internal contacts, Monticello is farther west than the external contacts made it; and you may, if you judge proper, take a mean of the results; but if, as you suggest, there are doubts of the accuracy of the times of the beginning and end of the eclipse, it will be better to depend on the inclosed statement alone, until future observations offer to correct it.

I am, Sir, with sincere and great respect, Your most obedient servant,

William Lambert.

RC (DLC); addressed: “Thomas Jefferson, late president [of the U. States, and] President [of the American philosophical Society, Monticello, Virginia]” (trimmed, with missing portion conjectured from address of Lambert to TJ, 23 Apr. 1812); endorsed by TJ as received 12 Jan. 1812 and so recorded in SJL. Enclosure: Lambert to TJ, 8 Jan. 1812.

Index Entries

  • astronomy; and calculations of Monticello’s longitude search
  • astronomy; and solar observations search
  • Lambert, William; calculates Monticello’s longitude search
  • Lambert, William; letters from search
  • Madison, James, Bishop; and W. Lambert’s astronomical calculations search
  • Monticello (TJ’s estate); longitude of search
  • sun; and calculation of longitude search
  • sun; annular eclipse of1811observed search