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Thomas Jefferson’s Notes on the Latitude of Willis’s Mountain, [ca. 19 December 1811]

Notes on the Latitude of Willis’s Mountain

[ca. 19 Dec. 1811]

Latitude of Willis’s mountain by observations of the Sun’s meridian altitude taken from the peak on the right side of the gap, & next adjacent to it, as seen from Monticello.

º
1811.  Nov.  21.  Meridian alt. of ☉ by observn*  32 37 20 1
Dec. 18. 29 2 50 2
19 29 4 50 3

the 1st by Th:J. the 2. last by Th:J.R.


other elements for the calculation.

Willis’s mountains being 62.′ E. of the South as seen from Monto and 40.5 common miles distant, it’s meridian will be .72136 of a mile E. of yt of Monticello. a degree of longitude in Lat. 37º–30′ = 47.6 geogr. mi. = 54.74 com. miles then .72136 of a common mile = 47.46 of longitude

º
which subtracted from ye long. of Monto  78 50 18.877
gives diffce of long. betw Greenwich & W’s M.  78 49 31.477
    º
Nov. 21.  ☉’s meridian altitude by observn 32 37 207
 
– refraction 1 29  
+ parallax      8     1 21
true Alt. of ☉’s center 32 35 598
90      
Zenith distance 57 24  19
º
☉’s decln at Greenwich   19 48 13
increase for 78º– 50′– 1910     2 48.8 19 50 56
37 33  5
 
Dec.11 18. ☉’s merid. alt. by observn  
°
  * 29 2 50
– refraction 1 42  
+ parallax      8     1 34
true alt. of ☉’s center 29 1 16
90      
Zenith distance 60 58 44
°
☉’s decln Greenwich 23 23 34
increase for 78º– 50′– 1912       17 23 23 34
37 35 1013
   
Dec. 19.  Merid. Alt. of ☉ by observn 29 4 5014
 
– refraction 1 42  
+ parallax      8     1 34
true alt. of ☉’s center. 29 3 1615
90      
Zenith distance 60 56 4416
°
☉’s decln at Greenwich 23 25 18
increase for 78º– 50′– 1917       11 23 25 29
 Lat. of Willis’s Mountain 37 31 1518
Th:J.R’s observn of Dec. 18. gives Lat.           37 35 1019
19. 37 31 1520
75 6 2521
mean 37 33 12.5 22
Th:J’s observation Nov. 21. gives 37 33  523
 difference        7.5″
  Lat. of Monticello 38 8
  W’s Mountn 37 33  5
 difference 34 55 = 40.15 miles

MS (Roger W. Barrett, Chicago, 1947); written entirely in TJ’s hand on both sides of a single sheet; undated.

On 20 Nov. 1811 TJ was at Mill Brook, the residence of his son-in-law John Wayles Eppes, located in eastern Buckingham County about three miles from Willis’s Mountain. He was staying at Poplar Forest on 18 and 19 Dec. 1811 (MB description begins James A. Bear Jr. and Lucia C. Stanton, eds., Jefferson’s Memorandum Books: Accounts, with Legal Records and Miscellany, 1767–1826, 1997, The Papers of Thomas Jefferson, Second Series description ends , 2:1271, 1272).

th:j.r.: Thomas Jefferson Randolph. The geographical (geogr.) mile is defined as one minute of arc along the equator, or approximately 1,850 meters (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 ).

1Reworked from “32–35–40.”

2Reworked from “29–2–10.”

3Reworked from “29–3–10.”

4TJ here canceled “observn.”

5Reworked from “35.”

6Reworked from “45.”

7Reworked from “32–35–40.”

8Reworked from “32–34–19.”

9Reworked from “57–25–41.”

10Reworked from “78°–34′–20″.”

11Verso begins with this word.

12Reworked from “78°–34′–20″.”

13Reworked from “37–36–30.”

14Reworked from “29–3–10.”

15Reworked from “29–1–36.”

16Reworked from “60–58–24.”

17Reworked from “78°–34′–20″.”

18Reworked from “37–32–55.”

19Reworked from what appears to be “37–37–13.”

20Reworked from what appears to be “37–32–15.”

21Reworked from “75–9–28.”

22Reworked from “37–34–14.”

23Reworked from “37–32–[  ].”

Authorial notes

[The following note(s) appeared in the margins or otherwise outside the text flow in the original source, and have been moved here for purposes of the digital edition.]

* 

*  °
65 18
      3 20  error of4 instrument
65 14 40
÷ 2 32 37 20

* 

* °
58  9  by the instrumt
      3 20  error of instrumt
58 5 40
÷ 2. 29 2 50

 

58 13  by the instrumt
      3 20  error of instrumt
58 9 40
÷ 2. 29 4 50

Index Entries

  • astronomy; and calculations of Monticello’s longitude search
  • Buckingham County, Va.; TJ travels through search
  • Eppes, John Wayles (TJ’s son-in-law); TJ visits search
  • geography; and TJ’s calculations of latitude search
  • Jefferson, Thomas; Writings; Notes on the Latitude of Willis’s Mountain search
  • Monticello (TJ’s estate); latitude of search
  • Monticello (TJ’s estate); longitude of search
  • Poplar Forest (TJ’s Bedford Co. estate); TJ visits search
  • Randolph, Thomas Jefferson (TJ’s grandson; Jane Hollins Nicholas Randolph’s husband); and latitude of Willis’s Mountain search
  • Willis’s Mountain; TJ takes latitude of search