Thomas Jefferson Papers

Thomas Jefferson to John Wood, 1 April 1816

To John Wood

Monticello. Apr. 1. 16.


I have duly recieved your favor of the 16th Ult. expressing your wish to be employed in the survey of the exterior boundaries of the state, under the 7th section of the act providing for a general map of the state, and I shall very conscientiously espouse your wish with the Executive from a conviction of your superior qualifications for that service. I have the fitter occasion of doing it, as I now have under consideration a letter from the Governor consulting me on the execution of the act. this act presents very extensive views, which will require much developement. the first member of the 7th section which you wish to undertake calls for two very distinct operations. that on the tidewaters must be aided by nautical means, the soundings being required, as well as the courses of the rivers. that above the tidewaters is what I presume you wish to undertake. the following is a general view of what is to be done.

Mountains.  1. a continued survey along their ridges.
2. a notation of their gaps.
3. their elevation.
4. the breadth of their bases.
Rivers. 5. their courses.
6. their breadths?
7. their fall?
General. 8. Latitudes and Longitudes?

Instruments.—for the 1st 2d 5th & 6th operations will a Theodolite with telescopes be too troublesome of management? and will a Circumferentor with a graduated rim, a fixed, and a moveable Index to take angles independant of the needle, and cross-spirit levels on the face of the plate, be sufficient?

3d the uncertainty of finding good baselines seems to render the geometrical admeasurement of heights less practicable than the barometrical, which the latter theories have brought to quite a sufficient correctness.

7th would the barometrical variations be sufficient for this? I doubt it; & if not I know no other method but what would make the undertaking more troublesome than useful: altho it would really be both curious & desirable, as would also be the velocity of the general current, if obtainable.

8. I presume a good Hadley’s sextant best for these operations.

I have distinguished by a ? the operations not expressly called for by the act, but which ought not to be left out of so great a work.

I should be very glad if you would take these several articles into consideration, and favor me with your views on them, adding any others omitted by me, and which may appear to you important. in hopes you will do me this kindness with as little delay as your convenience admits, I will withold for a while my answer to the Governor on this branch of the subject.

I do not know whether you have paid so particular an attention to mineralogy, and especially to the late geological systems, as to enable you to unite this object of the act with the other. it would be a convenient, as well as economical association. Accept the assurance of my esteem & respect.

Th: Jefferson

PoC (DLC); at foot of first page: “Mr John Wood.”

A circumferentor is a surveying “instrument consisting of a flat brass bar with sights at the ends and a circular brass box in the middle, containing a magnetic needle, which plays over a graduated circle; the whole being supported on a staff or tripod” (OED description begins James A. H. Murray, J. A. Simpson, E. S. C. Weiner, and others, eds., The Oxford English Dictionary, 2d ed., 1989, 20 vols. description ends ). A photograph of one of these devices is reproduced elsewhere in this volume.

Index Entries

  • An Act to provide an accurate chart of each county and a general map of the territory of this Commonwealth (1816) search
  • circumferentor search
  • Hadley, John; sextant of search
  • maps; of Virginia search
  • mineralogy; of Va. search
  • Nicholas, Wilson Cary (1761–1820); as Va. governor search
  • scientific instruments; circumferentors search
  • scientific instruments; sextants search
  • scientific instruments; theodolites search
  • sextant; for surveying search
  • surveying; and new map of Va. search
  • theodolite search
  • Virginia; maps of search
  • Wood, John (ca.1775–1822); as Va. state surveyor search
  • Wood, John (ca.1775–1822); letters to search