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Thomas Jefferson’s Notes on the Canal Locks and Manufacturing Mill at Shadwell, 11 May 1817

Notes on the Canal Locks and Manufacturing Mill at Shadwell

Measures taken at the locks & large mill, by myself May 11. 17.

the water was running 4½ I. deep over the waste.

surface of water in canal above that in upper chamber				8¼ I	0–8	½
depth of water in	upper chamber,	from it’s surface to it’s floor		6 f. 6 I.	6–6
	middle do	do		1–4
	lowest do	do		1–8
clear lift of	middle lock	7.f. 6 I.			7–6
	Lowest do	7 f 8 I	deduct depth of water—leaves		6–0
clear width of the chambers		8.f.			20–4	½
each recess is 9.I.			deduct depth on waste		4	½
clear width at recesses		9 f. 6			20–0
clear length of each chamber inside 68.f. 6.I.					f
the floor of the lowest chamber being 1.f. too high, call the whole					21–0
then 3. lifts of 7.f. each accomplishes it

Mill
from surface of water in the canal to bottom of forebay or top of wheel	2	f 9I.
diam. of wheel 14.f.	14	–0
bottom of wheel above surface of river at the tail 2.f.	2
	18	–9
deduct depth of water on the waste		4½
leaves height of waste above the surface of the river at the tail	18	–4½
height of waste above surface of river at the tail of the lock as above	20	–0
this diffce may be the fall in the river from tail of lock to tail of mill.	1	–7½′1

Stone work for locks of 3. chambers of 7.f. lift each. exclusive of foundations.
			f
3.	chambers of 70.f. length clear, for both sides		420
38.	abutments @ 11 f–8. I apart, 8.f. long at bottom 4.f. at top say 6.f.		228		perch
	running measure		648	=	40.
	thickness 4.f. at bottom, 2.f. at top. say 3.f. × 40 =				120.
	height above foundation, or floor 10 f. × 120.				1200.
4.	breast walls 16.f. long. make 64.f. running measure =	3.75 perch.
4.	f. thick	15.
7.	f. high. say for round numbers				100.
					1300.	perch.

	D
Stone mason for laying @ .75	975.
lime & planter’s work @ 1.75	2275.	)	by myself.
Carpenter’s & Smith’s work & digging		)	by myself.

Suppose the foundation of the lower lock sufficient, & the others going down to that
	foundation of middle chamber 7 f below it’s floor is		140 f = 8½ perch × 4 × 7 =	238.	perch.
		it’s breast 1. perch long, 4.f. thick, 7.f. to the floor		28
	foundation of upper chamber 14.f below it’s floor is		140 f = 8½ perch × 4 × 14 =	476
		it’s 2. breasts, 1. perch long, 4 f. thick 14.f. high is	140 f = 8½ × 4 × 14 =	112
				854.

		D
All together work done	by the mason	975	+	640.	=	1615
	by myself	2275	+	1494	=	3769	)	D
						5384		= 4385.	by myself
suppose Carpenter’s & smith’s work & digging worth						616
						6000

MS (MHi); written entirely in TJ’s hand on both sides of a single sheet; paper watermarked 1794.

1. Recto ends here, with last line of text trimmed but legible.

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Source Project: Jefferson Papers
Title: Thomas Jefferson’s Notes on the Canal Locks and Manufacturing Mill at Shadwell, 11 May 1817
Author: Jefferson, Thomas
Date: 11 May 1817

Cite as: “Thomas Jefferson’s Notes on the Canal Locks and Manufacturing Mill at Shadwell, 11 May 1817,” Founders Online, National Archives, https://founders.archives.gov/documents/Jefferson/03-11-02-0289. [Original source: The Papers of Thomas Jefferson, Retirement Series, vol. 11, 19 January to 31 August 1817, ed. J. Jefferson Looney. Princeton: Princeton University Press, 2014, pp. 348–350.]