Digital Archive of Slavery
to Freedom at Monticello   (beta)

1813.

Jan 7. a statement of the movement of the millworks at the foot of Monticello. the water wheel is calculated to turn 8. times in a minute.

Sawmill.	the greater cog wheel has		144. cogs
	and drives the balance wheel of		12. spurs

	which gives 12. strokes of the saw for 1. of the water wheel
	or 12 × 8 = 96 strokes of the saw in 1.′

Threshing machine.
	the lesser cogwheel has		112 cogs.
	drives a trundle of		14. rounds
	which is 8. for 1.

	the trundle has a horizontl cogwheel on same shaft of		48. cogs
	which drives the shaft of the drum wheel carrying		12. spurs
	which is 4. for 1.

	both together give 8 × 4 = 32. revolns of the drum for 1. of the water wheel or 32 × 8. revolns of the drum = 256 in 1′

Grist mill.	the lesser cogwheel of		112. cogs
	drives a wallower of		26. rounds
	on the shaft of which is a cog wheel of			54. cogs
	driving a trundle of			16. rounds.

	112	×	54	=	6048	= 14½ revolns of the millstone for 1. of the water wheel.
	26	×	16		416
					or 14½ × 8 = 116 revolns of the stone in 1.′

Millstones grind in proportion to the squares of their diameters. therefore the work of a 5.f stone is to that of one 6f. as 25 to 36.

their revolutions should be in the inverse ratio of their diameters, taking as a basis that a 52f. wheel 5f. stone turns 13. 90. times in a minute. then for the revolns of a 26f [. . .] 6f stone say as

	20 : 12 :: 13 :	13 × 12	= 7.8
		20

	6 : 5 :: 90 :	90 × 5	= 75
		6

water wheels should also have their revolns in the inverse ratio of their diameters, taking for a basis that a 12f wheel should turn 13 times in a minute: then for a 20f. wheel say as

	20 : 12 :: 13 ::	13 × 12	= 7.8
		20

the best motion for a saw is to make 115 strokes in a minute.

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the skirt of every millstone, of whatever size should move with the same velocity. per Gilmore. but Qu? at 34.f. a second. to wit a 5f. ston shd make 2. revolutions in a second?