Thomas Jefferson Papers

James Deneale to Thomas Jefferson, 2 July 1820

From James Deneale

Dumfries 2d July 1820


altho there is no persons opinion I would prefer to yours on any Invention of mine as none If favourable Could be more Useful to me, I should not have Ventured to trouble you, If the particular Situation in which I am placed had not renderd it Neccessary. A few days past I Enclosed the Instrument (I now Enclose to you) to a Mr Goolrick of Fredricksburg, he on returning it writes me amongst other things in the following words to wit “the Idea of the mapper I am Inclined is not a new one Mr Girrardin was at my house 6 or Seven years ago he lived at that time in the neighbourhood of Montecello and was Intimate with Mr Jefferson as Near as my recollection Serves me at So remote a period I think I was Informd that Mr Jefferson used Something Similar to your mapper in platting fields &C” as I Could Consciencously have Sworn that I believed I was the original Inventor of the Enclosed Instrument before the Receipt of this letter: I Cannot now do it untill I hear from you. altho I believe Mr Goolrick has mistaken Mr Girrardins description of your Instrument I have deemd it the Correct1 Course to Enclose it. may I ask the favour of you after Examining of it and If not your Invention to Say your opinion of it and If favourable2 whethr I may make that opinion Publick practical Surveyors here have born testimony to its usefulness. I have for many years platted by Latitude & departure instead of Course and distance. by this Means the distance was a Check upon my work. it occurd to me that an Instrument on the plan Sent would facilitate mapping as Neither protractor, Sweep, Scale,3 or Even dividers would be neccessary. after the mapping Sheet is prepared like the one Enclosed which by the by Should last a surveyor his life time as I have made dozens of maps on the same Sheet by drawing the outlines of the map with a black lead pencil when the map is prickd off on a Clean Sheet with a rubber the lines are rubbed out and the pricks Stopd by pressing on them the Sheet is ready for a new map. this Sheet Should be Carefully laid off4 and to prevent Blunders in Calculating the Contents of your map Each Inch Should be a red line as the map lies before you you may in a few minutes add up the Contents of your map. the mapper is on a scale of Forty poles to an Inch but may be made to any Scale, in useing this Instrument you map by the Latitude & departure of your Course and not by the Course and distance If your Latitude is north the angle of the Instrument is Upwards. If South downward the perpendicular of the Instrument is the Latitude and the Base the Departure it has occurd to me there is a possibility I am describing what you well know the thought has Stopt me your General Character assures me you will pardon this freedom

yours Respectfully

James Deneale

one word more. the Hypothenuse of this Instrument is intended as a ruler as it is on the same Scale as you rule the line you See If your distance is Correct


RC (DLC); endorsed by TJ as received 6 July 1820 and so recorded in SJL. RC (DLC); address cover only; with PoC of TJ to David Easton, 14 Jan. 1822, on verso; addressed: “Thomas Jefferson Esqr Montecello”; franked; postmarked Dumfries, 2 July.

James Deneale (ca. 1765–1821), miller and inventor, was a native Virginian. He resided by 1800 in Prince William County, where for many years he operated a gristmill and a nearby manufacturing mill on Quantico Creek just outside of Dumfries. Deneale received five federal patents during his lifetime: for a “Kiln for drying grain” in 1800, an improved threshing machine in 1804, a “perpetual oven” in 1806, a “wheat rubber” machine in 1809, and an “Instrument for mapping lands, &c.” on 3 Aug. 1820. He also served as county sheriff, 1816–17, and applied unsuccessfully to be principal engineer to the Virginia Board of Public Works in 1818. Having evidently lost both of his mills in 1821 at an auction for debt, Deneale died later that year at his home near Dumfries (Federal Gazette & Baltimore Daily Advertiser, 5 Jan. 1801; Alexandria Daily Advertiser, 12 Dec. 1804; Norfolk Gazette and Publick Ledger, 14 Dec. 1810; List of Patents description begins A List of Patents granted by the United States from April 10, 1790, to December 31, 1836, 1872 description ends , 22, 48, 58, 74, 215; Prince William Reliquary 4 [2005]: 31; Deneale to Bernard Peyton, 31 May 1818 [Vi: RG 57, Applications for Position of Principal Engineer]; Alexandria Gazette & Daily Advertiser, 16 Apr. 1821; Washington Daily National Intelligencer, 18 Sept. 1821).

A sweep is “an instrument used for drawing curves at a large radius” (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 ).

1Manuscript: “Corrct.”

2Preceding two words interlined.

3Manuscript: “Scole.”

4Manuscript: “of.”

5Remainder on separate sheet.

Index Entries

  • Deneale, James; identified search
  • Deneale, James; letter from search
  • Deneale, James; surveying instrument and method of search
  • dividers (surveying instrument) search
  • Girardin, Louis Hue; and TJ’s surveying instrument search
  • Goolrick, John search
  • inventions; surveying search
  • protractor search
  • scale (surveying instrument) search
  • surveying; and dividers search
  • surveying; and protractor search
  • surveying; and scale search
  • surveying; and sweep search
  • surveying; J. Deneale’s instrument and method of search
  • sweep (surveying instrument) search