Day-by-Day / May 16, 1803

May 16, 1803

The necessary instruments

In Washington City, President Thomas Jefferson writes a letter to Meriwether Lewis updating him on the status of the expedition’s navigational instruments. Jefferson is undecided about the need for a theodolite and says to refer to his mentors, Robert Patterson and Andrew Ellicott.

The “Necessary” Instruments

The necessary instruments: compass, surveyor's chains, artificial horizon, and chronometer

© 2014 by Kristopher K. Townsend. Permission to use granted under the Creative Commons Attribution-Share Alike 4.0 International license.

Above starting lower-left and moving clockwise: artificial horizon, surveyor’s chain, surveyors’ compass, chronometer, surveyors’ compass, octant, and compass.

Having read a draft of Jefferson’s instructions for the expedition, Lewis is confused about whether he should purchase navigational instruments. In the following letter, Jefferson clarifies his meaning.

Washington May 16. 1803.

Dear Sir

the instructions say that the necessary instruments ‘have been provided,’ which will be true when they recieve their ultimate form, date & signature, tho’ nothing was provided at the time of writing the rough draught. this will serve to correct the expression which has been misunderstood, and to let you know you are relied on to provide every thing for yourself.—

with respect to the theodolite, I wish you to be governed entirely by the advice of mr Patterson & mr Ellicott: as also as to the time piece & whatever else they think best. mr Garnett told us he had some good ones still on hand; which I remind you of, lest you should not be able to get one in Philadelphia. Accept my affectionate salutations.

Th: Jefferson[1]Thomas Jefferson to Meriwether Lewis, Founders Online, National Archives, founders.archives.gov/documents/Jefferson/01-40-02-0284 accessed 12 May 2022. [Original source: The Papers of Thomas … Continue reading

Ultimately, a theodolite was not included. For more on the navigational instruments and methods used on the expedition, see Deciphering the Celestial Data by Robert N. Bergantino and Celestial Reckoning by John Logan Allen.

 

Notes

Notes
↑1 Thomas Jefferson to Meriwether Lewis, Founders Online, National Archives, founders.archives.gov/documents/Jefferson/01-40-02-0284 accessed 12 May 2022. [Original source: The Papers of Thomas Jefferson, vol. 40, 4 March–10 July 1803, ed. Barbara B. Oberg. Princeton: Princeton University Press, 2013, p. 377.]

Discover More

  • The Lewis and Clark Expedition: Day by Day by Gary E. Moulton (University of Nebraska Press, 2018). The story in prose, 14 May 1804–23 September 1806.
  • The Lewis and Clark Journals: An American Epic of Discovery (abridged) by Gary E. Moulton (University of Nebraska Press, 2003). Selected journal excerpts, 14 May 1804–23 September 1806.
  • The Lewis and Clark Journals. by Gary E. Moulton (University of Nebraska Press, 1983–2001). The complete story in 13 volumes.

This site is provided as a public service by the
Logo: Lewis & Clark Trail Heritage Foundation
Lewis and Clark Trail Heritage Foundation
with cooperation and funding from the following organizations:

Unless otherwise noted, journal excerpts are from The Journals of the Lewis and Clark Expedition, edited by Gary E. Moulton, 13 vols. (Lincoln: University of Nebraska Press, 1983-2001).