Thomas Jefferson Papers
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From Thomas Jefferson to Charles Willson Peale, 23 April 1804

To Charles Willson Peale

Monticello Apr. 23. 1804.

Dear Sir

Your Polygraph gave me so much satisfaction that I thought it worth while to bestow some time in contriving one entirely suited to my own convenience: it was therefore the subject of my meditations on the road, and on my arrival here I made the drawings which I now send you. I have adopted your idea of having it in the form of a desk to sit on one’s writing table, & not that of a box to shut up. I have reduced the size, by getting rid of all useless space, which was chiefly the margins on the outside of the machinery: but as I had not your’s present, it is possible the reduction especially in the North & South dimension, may be greater than can be admitted without reducing the size of the parallelograms, or the space they work in, neither of which would I venture to do, lest it might injure the action of the machinery. for I well know that hypothesis is one thing and experience another. if therefore I have not given as much field for the parallelograms to move on, as they have in yours, my drawings must be altered in that particular. as I know the principal defect in yours is the liableness of the writing bed, under the brass frame, to warp, I have here suggested a method of guarding against that, without resorting to slate. in this I have very considerable faith. but these triangular boards, with the necessary breadth of the drawer (from which not an hair’s breadth can be spared) by pinching the two sidepieces in two, leave not, I am afraid, a sufficient bond between the fore & the aft part. the bottom board to be sure offers a considerable means of binding them together. so would the top board which forms the bed under the parallelograms, if1 clamped to the triangular boards with thin plates of iron screwed on. it would be important in this case that the grain of the top & bottom boards should run North & South. should this not be a strong enough connection, then by letting the triangular board opposite the separation of the drawers run through to the back it might form the spine and main strength of the whole machine, & would only add one inch to the dimension from East to West, making it 20½ I. instead of 23. I. should I also have made it so short from North to South (to wit 23. I.) as not to leave as much room for the play of the parallelograms as yours have, so that it may be necessary to enlarge it in that direction, then, by keeping the breadth & height of the drawers to what I have drawn them, the side pieces will not be so nearly pinched in two and will be considerable strengthners of the junction of the fore and aft parts. in some, or all of these ways, or better which will occur to yourself or your workman, this difficulty may be perhaps got over. instead of the cover sliding over the machinery in a semicircle as you propose, which including unnecessary space would look too bulky, I have proposed a light cover to take off and on, which you will see described. the screw for adjusting one of the pens (the right hand one which is most convenient for the copying one) to a hair’s breadth after it has been generally adjusted by the gage, is indispensible. it will only require 3. tubes, one within the other, instead of the 2. you use. the outer one you know is fixed to the machinery, & the one within that holds the pen & lets it turn to it’s proper square for writing. but an inner one still might be inserted in this and have a few threads of a screw to adjust it to a hair’s breadth, the pen being held in this inner one. in this case by turning the inmost tube within the middle one the pen would be raised or depressed by the thread of the screw, & by turning the middle one within the outer one, it would be placed square with the line of writing. the outer fixed tube would of course be to be enlarged.

As you were so kind as to say that when you should have made one on the improved plan, you would exchange it for the box-one which you sent me, I have now to ask the favor of you to have one made immediately on the plan I here propose, and forwarded to me at Washington by water. I desired mr Barnes to enquire of you the price of the former, and remit you the money, which I hope he has done. Accept my friendly salutations & assurances of great esteem.

Th: Jefferson

RC (TxU); at foot of first page: “Mr. Peale.” PrC (DLC). Enclosures not found, but see below.

Although the drawings TJ enclosed have not been found, TJ’s papers include other sketches related to the polygraph that could date from this period. One may illustrate TJ’s ideas on the machine’s pen bar, with particular attention to the screws, mentioned above and also in TJ’s letter of 30 Mch. to Peale. Another shows half of a rectangle, with dimensions of 23 along the top and 32 along the right side, contained within half of an ellipse or oval. To the right, TJ wrote:

“I I
Peale’s polygraph is 32½ by 22¾
but may be reduced to 26. by 18½

the thickness of his stuff is 6½ eighths, & of the drawer stuff ⅜ [but the drawer stuff may be only ⅜ and 316 and there is no cross partition between the drawers.]

copying paper is 8½ by 10½

I
the height of his box behind is 6⅞
in front 1⅜

size of the brass frame 18⅜ by 11⅜ it’s breadth 1 116

height of the gallows above the inclined plane 15. I. at right ∠ to the inclination.

the sides of his pentagraph from center to center 8⅝ breadth of stuff 516

(MSS in CSmH, both undated and in TJ’s hand, including brackets; Silvio A. Bedini, Thomas Jefferson and His Copying Machines [Charlottesville, 1984], 66, 74-6).

1TJ here canceled “connected.”

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