Enclosure III: Short Description of the Cotton Gin, 28 October 1793
III
Short Description of the Cotton Gin
A Short Description of the Machine invented by the Subscriber1 for Ginning Cotton.2
The principal parts of this machine are, 1. The Frame. 2d. The cylinder. 3 The breastwork. 4 The clearer, and 5, The Hopper.
1st. The frame by which the whole work is supported and kept together, is of a square or parallelogramic form and proportioned to the other parts as may be most convenient.
2. The cylinder is of wood; its form is perfectly described by its name, and its dimensions may be from six to nine inches diameter, and from two to five feet in length.3 This cylinder is placed horizontally across the frame, leaving room for the clearer on one side, and the Hopper on the other. In the cylinder is fixed an Iron axis which may pass quite through, or consist only of gudgeons driven into each end.
There are shoulders on this axis, to prevent any horizontal variation, and it extends so far without the frame as to admit a winch at one end, by which it is put in motion, and so far at the other end as to receive the whirl by which the clearer is turned. The surface of the cylinder is filled with teeth, set in annular rows,4 which are at such a distance from each other as to admit a cotton seed to play freely5 in the space between them. The space between each tooth in the same row, is so small as not to admit a seed, nor a half seed to enter it. These teeth are made of stiff Iron wire; driven in6 the wood of the cylinder.7 The teeth are all inclined the same way and in such a manner, that the angle, included between the tooth and a tangent drawn from the point into which the tooth is driven, will be about 55 or 60 Degrees.8 The gudgeons of the cylinder run9 in brass boxes, each of which is in two parts, one of which is fixed in the wood of the frame, and the other is confined down10 upon the11 Axis with screws.12
III. The breastwork is fixed above the cylinder, parallel and contiguous to the same, It has transverse grooves or openings thro’ which the rows of teeth pass as the cylinder revolves and its use is to obstruct the seeds while the cotton is carried forward through the grooves by the teeth. The thickness of the breastwork is two and half or three inches, and the under side of it is made of iron or brass.
IV. The clearer is placed horizontal with and parallel to the cylinder. Its length is the same as that of the cylinder, and its diameter is proportioned by convenience. There are two, four or more brushes or13 rows of bristles, fixed in the surface of the clearer in such a manner that the ends of the bristles will sweep the surface of the14 cylinder. Its axis and boxes are similar to those of the cylinder. It is turned by means of a band and whirls; moves in15 contrary direction from the cylinder, by which it is put in motion and so far outruns it, as to sweep the cotton from the teeth as fast as it is carried through the breastwork. The periphery of the whirls is spherical and the band a broad strap of Leather.
V. One side of the hopper is formed by the breastwork, the two ends by the frame,16 and the other side is moveable from and towards the breastwork, so as to make the hopper more or less capacious.
The cotton is put into the hopper, carried through the breastwork by the teeth, brushed off from the teeth by the clearer and flies off from the clearer, with the assistance of the air,17 by its own centrifugal force. The Machine is turned by Water, Horses or in any other way, as is most convenient.
There are several modes of making the various parts of this machine, which, together with their particular shape and formation are pointed out and18 explained19 in a Description with Drawings, attested as the act directs,20 and lodged in the Office of the Secretary of State.
Eli Whitney21
Signed in presence of
Chauncey Goodrich
Councillor at Law Hartford
John Allen
Councillor at Law Litchfield
Tr (GEpFAR: RG 21, U.S. Circuit Court, District of Georgia, Savannah, Mixed Cases); copy made from lost original; undated, but presumably notarized on 28 Oct. 1793 with Enclosure I; subjoined to and forming part of Tr of 14 Mch. 1794 patent granting exclusive rights to run fourteen years from 6 Nov. 1793, George Washington and Secretary of State Edmund Randolph being signatory and counter-signatory, with certification by Attorney General William Bradford, all in a clerk’s hand; at head of text: “The Schedule referred to in these Letters Patent and making part of the same containing a Description in the words of the said Eli Whitney himself of an improvement in the mode of Ginning Cotton”; certified by Secretary of State James Madison (see note to Enclosure i above). Tr (DNA: RG 241, Restored Patent Specifications); undated; copy made 2 May 1841 from lost Tr of 14 Mch. 1794 patent and containing copy of certification by Madison of 26 Nov. 1803. Dft (CtY: Whitney Papers); undated; heavily emended text in Whitney’s hand and signed by him, the emended text through the first sentence of second section being recopied fair on a separate sheet and the top of another (see note 3 below); at head of text, possibly being partly in Whitney’s hand: “The true Copy. Phl. 8 March 94”; with notation in an unidentified hand describing the lost original: “(The schedule is written on parchment which is seperate from the Patent and connected with the Patent by a ribbon the ends of which are brought under the seal).” First printed in American Farmer, iv (1823), 380–1, with minor variations in wording and the addition of symbols and some amplifying language to key the text to accompanying illustrations of the model.
1. Preceding four words interlined in recopied portion of Dft (see note 3 below), where Whitney had first written the same words below this heading.
2. In canceled portion of Dft (see following note) this heading reads: “A <General> Short Description <of Whitney’s new invented Cotton Gin> of a machine for ginning cotton without refferences to the Drawings.” In recopied portion of Dft the following notation by Whitney is circled: “a description whereof is given in the words of the said A.B. himself in the schedule hereto annexed, and is made a part of these Presents.”
3. Emended Dft to this point recopied fair by Whitney on a separate page and (as recorded in note 21 below) the top of another, being keyed by him to replace the canceled text, which has only slightly variant wording except for heading given in preceding note.
4. In Dft Whitney here canceled “[…] the distance of about half an inch from each other. The [space?] between [each tooth?] in the same row is about one fourteenth of an inch.”
5. In Dft Whitney here canceled “every way.”
6. Dft and Tr in RG 241: “into.”
7. In Dft Whitney here canceled “and of an equal length.”
8. In Dft Whitney here canceled “[…]. After the teeth receive their inclination they are brought to an equal length and pointed.”
9. In Dft Whitney first wrote “This Cylinder runs” before revising the sentence to begin as above.
10. Word interlined in Dft.
11. In Dft Whitney here canceled what appears to be “top.”
12. In Dft Whitney here canceled “Remark.”
13. Preceding two words interlined in Dft.
14. Preceding three words interlined in Dft.
15. Dft and Tr in RG 241 here add “a.”
16. Word interlined in Dft in place of what appears to be “Clearer.”
17. Preceding clause interlined in Dft.
18. In Dft Whitney here canceled “discussed.”
19. In Dft Whitney here interlined and canceled “by the inventor.”
20. Preceding clause interlined in Dft in place of “(Dated Sept. AD One thousand seven hundred and ninety three).”
21. In Dft remainder of text is written on second separate page, as described in note 3 above.