From Thomas Pinckney, with Jefferson’s Note
London 29 Jany. 1794
My dear Sir
I have to acknowledge your private favor of the 12th. of December covering a bill for 13 st. which is duly honor’d. I wish the threshing machine may answer the purpose, I have no doubt that on a proper stream of water the effect of it would be astonishingly great and the principle being accurately described in the model may be applied to smaller machines for farmers whose strength of Cattle may not reach the power of this. Mr. Patersons Machine was worked by two strong horses at a time, the Diameter of his threshing wheel was greater than in your model being I think 8 feet and its velocity much less. The motion was given in a contrary direction whereby the grain instead of being thrown over the top of the wheel fell under it through a grating prepared for the purpose. Have you thought of the method used here occasionally of combing off the ears of the wheat? or of putting it as soon as threshed into cool subterraneous vaults, which I am told is the practice in Sicily? I am not without hopes that notwithstanding your former determination circumstances will have induced you to retain your situation beyond the time you had limited. I beg you to be assured, my dear Sir, that whether you continue in or retire from public office you possess the sincere attachment of Your affectionate & respectful Servt.
[Notes in TJ’s hand:]
Cogs &c of the wheels
78 ÷ 17 = 4.6
59 ÷ 13 = 4.5
53 ÷ 11 = 4.8
4.6 × 4.5 × 4.8 = 99.36
For every mile, by the hour, of the horse’s motion the threshing wheel turns 100 times a minute.
Viz. if the horse goes
|2||miles an hour, the wheel turns||100.||times a minute|
RC (DLC); at foot of first page: “Mr. Jefferson”; at head of text: “(Private)”; with note by TJ at foot of text; endorsed by TJ as received 29 Apr. 1794 and so recorded in SJL. PrC (ScHi: Pinckney Family Papers).