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Enclosure: Thomas Jefferson’s Summary of Weather Observations, 1810–1816, [ca. 11 April 1818]

Enclosure

Summary of Weather Observations, 1810–1816

[ca. 11 Apr. 1818]

1. the greatest & least height of the thermometer every day.
2. the greatest, least, & mean height of the thermom. in every month, with the mean of each year, & the mean of the 7. years, which last1 was 55½°.
3. the minimum & maximum of the whole term, to wit 5½° and 94½°
4. the number of freezing nights in a winter [50.] & of freezing days [10.]
5. how long fires are necessary in our apartments. to wit 4. months constant & evening & morning one month before & after that term.
6. the earliest frost in Autumn Oct. 72–26 and the latest in spring Mar. 19–May 15
7. the earliest ice in Autumn Oct. 24–Nov. 15. and latest in spring Mar. 8–Apr. 10.
8. the quantity of water falling in a year. average 47.218 I.
9. the number of rains in the year. 89.
10. the number of fair days. average 5. to the week.
11. the quantity of snow 22½ I. average; covers the ground 22. days.
12. the number of days each wind prevails thro’ the year.
13. the flowering of plants, ripening of their fruit, the coming to table of the productions of the garden, arrival of birds, insects Etc.
14. the temperature of the springs. 54½° the outer air being at 75.°
15. the latitude of the place of observation [Monticello] 37°–57′–51″–26

extract from No 13.
the Peach blossoms Mar. 9. to Apr. 4.
the tick appears 15  2 
the house Martin 18  9 
Asparagus comes to table 23  14 
the Lilac blooms Apr. 1. 28 
the red-bud blooms 2  19 
the whip-poor Will is heard 2  21 
the dogwood blossoms 3  22 
the Locust blossoms 25  to May 17.
garden pea comes to table [unforced]  May 3. 25 
strawberries ripe 3. 25 
fireflies appear 8.
cherries ripe 18. 25 
wheat harvest begins June 21. 29 
cucumbers at table [unforced] 22  to July 5 
peaches ripe July 7. 21.
Catydids or3 sawyers heard 14  20.

average of every month. prevalence of
the several winds
stated in days of a year.
therm. rain    
Jan. 36 3.66
Feb. 40 3.47 N. 61.       
Mar. 46 2.92 N.E. 29 
Apr. 56 ½ 3.59 E. 15 
May 61 ½ 5.60 S.E. 16 
June 72 3.47 S. 60 
July 75 6.56 S.W. 66 
Aug. 73 4.06 W. 47 
Sep 67 5.96 N.W. 71 
Oct. 57 3.40 365 
Nov. 45 ½ 2.92
Dec. 37 1.56

MS (MHi: Mary Anna Bigelow Autograph Collection); subjoined to RC of covering letter; entirely in TJ’s hand; undated; corner torn, with missing text supplied from PoC; brackets in original. PoC (DLC); subjoined to PoC of covering letter.

1Word interlined.

2Reworked from “27.”

3Preceding two words (more commonly, katydids) not in TJ’s Analysis.

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