Thomas Jefferson Papers
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Thomas Jefferson to Wilson Cary Nicholas, 19 April 1816

To Wilson Cary Nicholas

Poplar Forest Apr. 19. 16.

Dear Sir

In my letter of the 2d inst. I stated, according to your request what occurred to me on the subjects of Defence and Education; and I will now proceed to do the same on the remaining subject of your’s of Mar. 22. the construction of a general map of the state. for this the legislature directs that there shall be

I. a topographical survey of each county.
II. a General survey of the Outlines of the state, and it’s leading features of rivers and mountains.
III. an Astronomical survey for the correction & collocation of the others, and
IV. a Mineralogical survey.

I. altho’ the topographical survey of each county is referred to it’s court in the first instance, yet such a controul is given to the Executive as places it effectively under his direction. that this controul must be freely and generally exercised I have no doubt. nobody expects that the justices of the peace in every county are so familiar with the astronomical and geometrical principles to be employed in the execution of this work as to be competent to decide what candidate possesses them in the highest degree, or in any degree: and indeed I think it would be reasonable, considering how much the other1 affairs of the state must engross of the time of the Governor & Council, for them to make it a prerequisite for every candidate to undergo an examination by the Mathematical professor of Wm & Mary college, or some other professional character, and to ask for a special and confidential report of the grade of qualification of each candidate examined. if one, competently qualified, can be found for every half dozen counties, it will be as much perhaps as can be expected.

Their office will be to survey the Rivers, Roads, Mountains and Boundaries of each county.

1. a proper division of the surveys of the Rivers between them and the General surveyor might be to ascribe to the latter so much as is navigable, and to the former the parts not navigable, but yet sufficient for working machinery, which the law requires. on these they should note confluences, other natural & remarkable objects, towns, mills or other machines, ferries, bridges, crossings of roads, passages thro’ mountains, mines, quarries Etc.

2. in surveying the Roads, the same objects should be noted, and every permanent stream crossing them, and these streams should be laid down according to the best information they can obtain, to their confluence with the main stream.

3. the Mountains, other than those ascribed to the General surveyor should be laid down by their names and bases which last will be generally designated by the circumscription of water courses and roads on both sides, without a special survey around them. their gaps are also required to be noted.

4. on the Boundaries the same objects should be noted. where a boundary falls within the operations of the General surveyor, it’s survey by them should be dispensed with, and where it is common to two counties, it might be ascribed wholly to one, or divided between the surveyors respectively. all these surveys should be delineated on the same scale, which the law directs, I believe, (for I have omitted to bring the copy of it with me to this place.) if it has not fixed the scale, I think about half an inch to the mile would be a convenient one, because it would generally bring the map of a county within the compass of a sheet of paper. and here I will suggest what would be a great desideratum for the public, to wit, that a single sheet map, of each county separately, on a scale of half an inch to the mile be engraved and struck off. there are few housekeepers who would not wish to possess a map of their own county, many would purchase those of their circumjacent counties, and many would take one of every county, & form them into an Atlas, so that I question if as many copies of each particular map would not be sold as of the general one. but these should not be made until they recieve the astronomical corrections, without which they can never be brought together and joined into larger maps, at the will of the purchaser.

Their instrument should be a Circumferentor with cross spirit levels on it’s face, a graduated rim, and a double Index, the one fixed, the other moveable, with a Nonius on it. the needle should never be depended on for an angle.

II. the General survey divides itself into two distinct operations; the one on the tide waters, the other above them.

On the tide-waters the State will have little to do. some time before the war, Congress authorised the Executive to have an accurate survey made of the whole sea-coast of the US. comprehending, as well as I remember, the principal bays and harbors. a mr Hassler, a mathematician of the first order from Geneva, was engaged in the execution and was sent to England to procure proper instruments. he has lately returned with such a set as never before crossed the Atlantic, and is scarcely possessed by any nation on the continent of Europe. we shall be furnished then by the General government with a better survey than we can make, of our sea-coast, Chesapeak bay, probably the Potomak to the Navy yard at Washington, and possibly of James river to Norfolk, and York river to York town. I am not however able to say that these, or what other are the precise limits of their intentions. the Secretary of the Treasury would probably inform us. above these limits, whatever they are, the surveys & soundings will belong to the present undertaking of the state: and if mr Hassler has time, before he commences his general work, to execute this for us, with the use of the instruments of the US. it is impossible2 we can put it into any train of execution equally good: and any compensation he may require, will be less than it would cost to purchase instruments of our own, and have the work imperfectly done by a less able hand. if we are to do it ourselves, I acknolege myself too little familiar with the methods of surveying a coast and taking soundings, to offer any thing on the subject approved by practice. I will pass on therefore to

the General Survey of the Rivers above the tide waters, the Mountains, and external Boundaries.

1. Rivers. I have already proposed that the General survey shall comprehend these from the tide-waters as far as they are navigable only. and here we shall find one half of the work already done, and as ably as we may expect to do it. in the great controversy between the Lords Baltimore & Fairfax, between whose territories the Potomak from it’s mouth to it’s source was the chartered boundary, the question was which branch, from Harper’s ferry upwards, was to be considered as the Potomak? two able mathematicians therefore were brought over from England at the expence of the parties, and under sanction of the sentence pronounced between them, to survey the two branches, and ascertain which was to be considered as the Main stream. Ld Fairfax took advantage of their being here to get a correct survey by them of his whole territory, which was bounded by the Potomak, the Rappahanoc, and a line uniting their two3 sources. the work was executed, as was believed in the most accurate manner, their survey was doubtless filed and recorded in Ld Fairfax’s office, and I presume it still exists among his land papers. he furnished a copy of that survey to Colo Fry and my father, who entered it on a reduced scale into their map. as far as latitudes, and admeasurement accurately horizontal could produce exactness, I expect this survey is to be relied on. but it is lawful to doubt whether it’s longitudes may not need verification; because at that day, the corrections had not been made in the lunar tables, which have since introduced the method of ascertaining the longitude by the lunar distances; & that by Jupiter’s satellites was impracticable in an ambulatory survey. the most we can count on is that they may have employed some sufficient means to ascertain the longitude of the first source of the Potomak, the meridian of which was to be Ld Baltimore’s boundary. the longitudes therefore should be verified and corrected, if necessary; and this will belong to the Astronomical survey.

The other rivers only then, from their tidewaters up as far as navigable, remain for this Operator, and on them the same objects should be noted as proposed in the county surveys; and, in addition, their breadth at remarkable parts, such as the confluence of other streams, falls, and ferries, the soundings of their main channels, bars, rapids, and principal sluices thro’ their falls, their current at various places, and, if it can be done without more cost than advantage, their fall between certain stations.

2. Mountains. I suppose the law contemplates, in the general survey, only the principal continued ridges, and such insulated mountains as being correctly ascertained in their position, and visible from many and distant places, may, by their bearings, be useful correctives for all the surveys, and especially those of the counties. of the continued ridges, the Alleganey, North mountain & Blue ridge are principal. ridges of partial lengths may be left to designation in the county surveys. of insulated mountains there are the Peaks of Otter in Bedford, which I believe may be seen from about 20 counties, Willis’s mountains in Buckingham, which from their detached situation, and so far below all other mountains, may be seen over a great space of country, Peter’s mountain in Albemarle, which, from it’s eminence above all others of the South West ridge, may be seen to a great distance, probably to Willis’s mountain, and with that and the Peaks of Otter furnishes a very extensive triangle; and doubtless there are many unknown to me, which being truly located, offer valuable indications and correctives for the county surveys. for example. the sharp peak of Otter being precisely fixed in position by it’s longitude and latitude, a simple observation of latitude, taken at any place from which that peak is visible, and an observation of the angle it makes with the meridian of the place, furnish a right angled spherical triangle, of which the portion of meridian intercepted between the latitudes of the place, and peak, will be one side. with this and the given angles, the other side, constituting the difference of longitude, may be calculated, and thus by a correct position of these commanding points, that of every place from which any one of them is visible, may, by observations of latitude and bearing, be ascertained in longitude also. if two such objects be visible from the same place, it will afford, by another triangle, a double correction.

The gaps in the continued ridges, ascribed to the General surveyor, are required by the law to be noted; and so also are their heights. this must certainly be understood with some limitation, as the height of every knob in these ridges could never be desired. probably the law contemplated only the eminent mountains in each ridge, such as would be conspicuous objects of observation to the country at great distances, and would offer the same advantages as the insulated mountains. such eminences in the Blue ridge will be more extensively useful than those of the more Western ridges. the height of gaps also, over which roads pass, were probably in view.

But how are these heights to be taken, & from what base? I suppose from the plain on which they stand. but it is difficult to ascertain the precise horisontal line of that plain, or to say where the ascent above the general face of the country begins. where there is a river or other considerable stream, or extensive meadow plains near the foot of a mountain, which is much the case in the vallies dividing the Western ridges, I suppose that may be fairly considered in the level of it’s base, in the intendment of the law. where there is no such term of commencement, the Surveyor must judge, as well as he can from his view, what point is in the general level of the adjacent country. How are these heights to be taken, and with what instrument? where a good base can be found, the geometrical admeasurement is the most satisfactory. for this a theodolite must be provided of the most perfect construction, by Ramsden or Troughton if possible; and for horizontal angles it will be the better of two telescopes. but such bases are rarely to be found. when none such, the height may still be measured geometrically, by ascending or descending the mountain with the theodolite, measuring it’s face from station to station, noting it’s inclination between these stations, and the hypothenusal difference of that inclination, as indicated on the vertical ark of the theodolite. the sum of the perpendiculars corresponding with the hypothenusal measures, is the height of the mountain. but a barometrical admeasurement is preferable to this. since the late improvements in the theory they are to be depended on nearly as much as the geometrical, and are much more convenient and expeditious. the barometer should have a sliding Nonius and a thermometer annexed, with a screw at the bottom to force up the column of mercury solidly. without this precaution they cannot be transported at all; and even with it, they are in danger from every severe jolt. they go more safely on a baggage horse than in a carriage. the heights should be measured on both sides to shew the rise of the country at every ridge.

Observations of longitude and latitude should be taken by the surveyor at all confluences of considerable streams, and on all mountains of which he measures the heights, whether insulated, or in ridges. for this purpose he should be furnished with a good Hadley’s circle of Borda’s construction, with three limbs & Nonius indexes. if not to be had, a sextant of brass, and of the best construction may do; and a Chronometer. to these is to be added a Gunter’s chain, with some appendix for plumbing the chain.

3. the External Boundaries of the state. to wit, Northern, Eastern, Southern and Western. the Northern boundary consists of 1. the Potomak. 2. a Meridian from it’s source to Mason & Dixon’s line. 3. a continuation of that line to the meridian of the North Western corner of Pensylvania, and 4. of that meridian to it’s intersection with the Ohio. 1. the Potomak is supposed, as beforementioned to be surveyed to our hand. 2. the Meridian from it’s source to Mason and Dixon’s line was, I believe surveyed by them when they run the dividing line between Ld Baltimore & Penn. I presume it can be had from either Annapolis or Philadelphia, and I think there is a copy of it, which I got from Dr Smith, in an Atlas of the library of Congress. nothing better can be done by us. 3. the continuation of Mason & Dixon’s line and the meridian from it’s termination to the Ohio was done by mr Rittenhouse & others, and copies of their work are doubtless in our offices as well as in those of Pensylvania. what has been done by Rittenhouse can be better done by no one.

The Eastern boundary being the sea coast we have before presumed will be surveyed by the general government.

The Southern boundary. this has been extended and marked in different parts in the chartered latitude of 36.° 30.′ by three different sets of Commissioners. the Eastern part by Dr Byrd and other Commissioners from Virginia & N. Carolina: the middle by Fry & Jefferson from Virginia, & Churton & others from N. Carolina: and the Western by Dr Walker and Daniel Smith now of Tennissee. whether Byrd’s survey now exists, I do not know. his journal is still in possession of some one of the Westover family, and it would be well to seek for it in order to judge of that portion of the line. Fry and Jefferson’s journal was burnt in the Shadwell house about 50. years ago, with all the materials of their map. Walker & Smith’s survey is probably in our offices. there is a copy of it in the Atlas beforementioned. but that survey was made on the spur of a particular occasion, and with a view to a particular object only. during the revolutionary war we were informed that a treaty of peace was on the carpet in Europe on the principle of Uti possidetis: and we dispatched those gentlemen immediately to ascertain the intersection of our Southern boundary with the Missisipi, and ordered Colo Clarke to erect a hasty fort on the first bluff above the line, which was done as an act of possession. the intermediate line between that & the termination of Fry & Jefferson’s line was provisory only, and not made with any particular care. that then needs to be resurveyed as far as the Cumberland mountain. but the Eastern & Middle surveys will only need, I suppose, to have their longitudes rectified by the Astronomical surveyor.

The Western boundary, consisting of the Ohio, Big Sandy & Cumberland mountain, having been established while I was out of the country, I have never had occasion to enquire whether they were actually surveyed and with what degree of accuracy. but this fact being well known to yourself particularly, and to others who have been constantly present in the state, you will be more competent to decide what is to be done in that quarter. I presume indeed that this boundary will constitute the principal, and most difficult part of the operations of the General surveyor.

The injunctions of the act to note the magnetic variations merit diligent attention. the law of those variations is not yet sufficiently known to satisfy us that sensible changes do not sometimes take place at small intervals of time and place. to render these observations of the variations easy, and to encourage their frequency, a copy of a table of amplitudes should be furnished to every surveyor, by which, wherever he has a good Eastern horison, he may, in a few seconds, at sunrise, ascertain the variation. this table is to be found in the book called the Mariner’s compass rectified; but more exactly in the Connaissance des tems for 1778. and 1788. all of which are in the library of Congress. it may perhaps be found in other books more easily procured, and will need to be extracted only from 36½.° to 40.° degrees of latitude.

III. The Astronomical survey. this is the most important of all the operations. it is from this alone we are to expect real truth. measures and rhumbs taken on the spherical surface of the earth, cannot be represented on a plain surface of paper without astronomical corrections: and, paradoxical as it may seem, it is nevertheless true that we cannot know the relative position of two places on the earth, but by interrogating the sun, moon, and stars. the Observer must therefore correctly fix, in longitude and latitude, all remarkable points from distance to distance. those to be selected of preference are the confluences, rapids, falls and ferries of water courses, summits of mountains, towns, courthouses, and angles of counties. and where these points are more than a third, or half a degree distant, they should be supplied by observations of other points, such as mills, bridges, passes thro’ mountains Etc. for in our latitudes, half a degree makes a difference of three eighths of a mile in the length of the degree of Longitude. these points first laid down, the intermediate delineations to be transferred from the particular surveys to the general map, are adapted to them by contractions or dilatations. the Observer will need a best Hadley’s circle of Borda’s construction, by Troughton if possible (for they are since Ramsden’s time) and a best chronometer.

Very possibly an Equatorial may be needed. this instrument set to the observed latitude, gives the meridian of the place. in the lunar observations at sea this element cannot be had, and in Europe by land, these observations are not resorted to for longitudes, because at their numerous fixed Observatories they are prepared for the better method of Jupiter’s satellites. but here where our geography is still to be fixed by a portable apparatus only, we are obliged to resort, as at sea, to the lunar observations; with the advantage however of a fixed meridian. and altho’ the use of a meridian in these observations is a novelty yet, placed under new circumstances, we must countervail their disadvantages by what ever new resources they offer. it is obvious, that the observed distance of the Moon from the meridian of the place, and her calculated distance from that of Greenwich at the same instant, give the difference of meridians, without dependance on any measure of time; by addition of the observations, if the moon be between the two meridians, by subtraction if East or West of both. the association therefore of this instrument with the Circular one, by introducing another element, another process, and another instrument, furnishes a test of the observations with the Hadley, adds to their certainty, and, by it’s corroborations, dispenses with that multiplication of observations which is necessary with the Hadley when used alone. this idea however is suggested by theory only; and it must be left to the judgment of the Observer, who will be employed, whether it would be practicable and useful. to him, when known, I shall be glad to give further explanations. the cost of the Equatorial is about the same with that of the Circle, when of equal workmanship.

Both the Surveyor and Astronomer should journalise their proceedings daily, and send copies of their journals monthly to the Executive, as well to prevent loss by accident, as to make known their progress.

IV. Mineralogical survey. I have never known in the US. but one eminent mineralogist, who could have been engaged on hire. this was a mr Goudon from France who came over to Philadelphia 6. or 7. years ago. being zealously devoted to the science, he proposed to explore the new field which this country offered: but being scanty in means, as I understood, he meant to give lectures in winter which might enable him to pass the summer in mineralogical rambles. it is long since I have heard his name mentioned, and therefore do not know whether he is still at Philadelphia, or even among the living. the literary gentlemen of that place can give the information, or perhaps point out some other equal to the undertaking.

I believe I have now, Sir, gone over all the subjects of your letter. which I have done with less reserve to multiply the chances of offering here and there something which might be useful. it’s greatest merit however will be that of evidencing my respect for your commands and of adding to the proofs of my great consideration & esteem.

Th: Jefferson

RC (MHi). PoC (DLC: TJ Papers, 207:36822–3, 36825, 36824, 36826–7); at foot of first page: “Govr Nicholas.”

English-born professionals who were chosen to survey the two branches of the Potomac River, 1736–37, included William Mayo and Robert Brooke (Sarah S. Hughes, Surveyors and Statesmen: Land Measuring in Colonial Virginia [1979], 85–6, 144–9; Robert A. Brock and Virgil A. Lewis, Virginia and Virginians [1888], 1:88). uti possidetis is the “doctrine that old administrative boundaries will become international boundaries when a political subdivision achieves independence” (Black’s Law Dictionary description begins Bryan A. Garner and others, eds., Black’s Law Dictionary, 7th ed., 1999 description ends ). For TJ’s instructions to George Rogers Clark, Thomas Walker, and Daniel Smith regarding the survey of the intersection of our southern boundary with the missisipi and the establishment of a fort at the mouth of the Ohio River, see PTJ description begins Julian P. Boyd, Charles T. Cullen, John Catanzariti, Barbara B. Oberg, and others, eds., The Papers of Thomas Jefferson, 1950– , 38 vols. description ends , 3:273–9. mr goudon: Silvain Godon.

1Word interlined.

2Manuscript: “impospossible.”

3Word interlined.

Index Entries

  • Allegheny Mountains; and map of Va. search
  • American Revolution; and U.S. territorial boundaries search
  • An Act to provide an accurate chart of each county and a general map of the territory of this Commonwealth (1816) search
  • astronomy; Jupiter search
  • astronomy; TJ on search
  • barometers; for surveying search
  • Blue Ridge Mountains; surveying of search
  • Borda, Jean Charles de; and surveying instruments search
  • Borda’s circle (surveying instrument) search
  • Brooke, Robert; surveyor search
  • Byrd, William (1674–1744); as boundary commissioner search
  • Calvert, Frederick, 6th Baron Baltimore; territory of surveyed search
  • Chesapeake Bay; survey of search
  • chronometers; for surveying search
  • Churton, William; surveyor search
  • circumferentor search
  • Clark (Clarke), George Rogers; surveys boundaries search
  • Connaissance des Temps: ou, des Mouvements célestes à l’usage des astronomes et des navigateurs search
  • Dallas, Alexander James; as secretary of the treasury search
  • Dixon, Jeremiah; surveyor search
  • equatorial (astronomical instrument); and surveying search
  • Fairfax, Thomas, 6th Baron Fairfax of Cameron; lands of surveyed search
  • Fry, Joshua; surveyor search
  • Godon, Silvain; TJ recommends search
  • Greenwich Observatory, England; and prime meridian search
  • Hadley, John; and astronomical instruments search
  • Hassler, Ferdinand Rudolph; and instruments for U.S. Coast Survey search
  • Hassler, Ferdinand Rudolph; and U.S. Coast Survey search
  • James River; survey of search
  • Jefferson, Peter (TJ’s father); surveyor search
  • Jupiter (planet) search
  • Library of Congress; works owned by search
  • maps; of Virginia search
  • Mason, Charles; surveyor search
  • Mayo, William; as surveyor search
  • mineralogy; and S. Godon search
  • mineralogy; of Va. search
  • Mississippi River; as geographical boundary search
  • Nicholas, Wilson Cary (1761–1820); as Va. governor search
  • Nicholas, Wilson Cary (1761–1820); letters to search
  • nonius; and surveying search
  • North Carolina; boundary with Va. search
  • Ohio River; as geographical boundary search
  • Peaks of Otter, Va.; used in surveying search
  • Penn, William; territory of surveyed search
  • Peter’s Mountain (Southwest Mountains); surveying of search
  • Potomac River; surveying of search
  • prime meridian search
  • Ramsden, Jesse; theodolite of search
  • Rappahannock River search
  • Rittenhouse, David; surveyor search
  • roads; in Va. search
  • scientific instruments; barometers search
  • scientific instruments; circumferentors search
  • scientific instruments; equatorials search
  • scientific instruments; reflecting circles search
  • scientific instruments; sextants search
  • scientific instruments; telescopes search
  • scientific instruments; theodolites search
  • scientific instruments; thermometers search
  • sextant; for surveying search
  • Shadwell (TJ’s estate); fire at search
  • Smith, Daniel; surveyor search
  • Smith, Dr.; gives map to TJ search
  • surveying; and chain search
  • surveying; and J. C. Borda’s circle search
  • surveying; and new map of Va. search
  • surveying; chronometer for search
  • surveying; nonius for search
  • telescopes; equatorial search
  • The Mariner’s Compass Rectified (A. Wakely) search
  • theodolite search
  • thermometers; mentioned search
  • Troughton, Mr.; scientific-instrument maker search
  • Virginia; and education search
  • Virginia; boundary of with N.C. search
  • Virginia; defense of search
  • Virginia; General Assembly search
  • Virginia; maps of search
  • Wakely, Andrew; The Mariner’s Compass Rectified search
  • Walker, Thomas (1715–94); as surveyor search
  • William and Mary, College of; faculty of search
  • Willis’s Mountain; surveying of search
  • York River; survey of search