Thomas Jefferson Papers

William Lambert to Thomas Jefferson, 28 June 1822

From William Lambert

City of Washington, June 28th 1822.


The method of determining the longitude of any place by occultations, and solar eclipses, has been, and perhaps, always will be considered among the best for that purpose. It must be acknowledged, that the process is tedious and laborious; but the accuracy of the results, when due care is taken in the operation, will amply compensate for the trouble of computing the necessary elements. In this method, particularly, we have it in our power, by a proper reduction of the latitude of the place, and of the Moon’s equatorial horizontal parallax, to find the longitude, allowing for the spheroidal form of the Earth, which, by other methods, susceptible of less accuracy, is seldom taken into view. The rough draft herewith inclosed, is intended by its author, for the use of the seminary near Charlottesville, in your neighbourhood; and I shall be gratified to learn, that the rules and process therein exhibited, have been, or may be serviceable in promoting a competent knowledge of that branch of science, with which they are connected.

I have the honor to be, with great respect, Your most Obedt servant,

William Lambert.

RC (ViU: TJP); addressed (trimmed): “[Thomas?] [Je]fferson, Monticello, Virginia”; endorsed by TJ as received 1 July 1822 and so recorded in SJL.

Index Entries

  • astronomy; and lunar calculations search
  • astronomy; and solar observations search
  • Lambert, William; and University of Virginia search
  • Lambert, William; astronomical calculations search
  • Lambert, William; letters from search
  • Lambert, William; lunar calculations search
  • latitude; and calculation of longitude search
  • moon; and astronomical calculations search
  • sun; and astronomical calculations search
  • Virginia, University of; Books and Library; books and manuscripts for search