Museum Augt. 27th. 1804.
Inclosed are the spiral springs you desire in yours of the 19th. instant The loop is easily made thus, cut off the spring to the length desired with cutting-nippors—with a knife open two rings, and then with Plyers twist them to a right angle.
I am much pleased by your approbation of this invention, and hope that others will also find the utility of it. The wire netting is certainly an important improvement of the cover, especially for a Public office. We are still making improvements in the manufacture of the Machinery—my Workmen are more expert in their work—my drilling machine is still more perfect, which is of vast importance. I wish Mr. Hawkins may not labour so long as I have done to overcome the difficulties of the first construction of the Machinery. I have wrote him long letters to acquaint him of my discoveries—and I have now several improvements to send him. I have lately seen in the Repertory of the Arts, his Patent right with a Plate of the several parts of the Polygraph and Physiognotrace, I wish I had the work before me that I might note several parts—one Idea which he has, I suppose lately conceived, is, the placing a pen to an irregular part of the Parallels for secreet writing, which he says, can only be decyphered by having a Polygraph with a simular fixture. This hint may set you to thinking of his mode, it is not defined by his figures that I remember, having only had a cursory view of the Book.
The 2d. paragraph of your letter, i.e. Six lines would be a great recommendation of the Polygraph, but I do not chuse to give them to the Printer without your approbation—however there is no occasion to hurry, especially as I have at present some demands not yet complyed with, and with hopes of still making the machine more perfect—in which point of view I shall be very thankfull for the aid of your corrective modifications, as we accord in sentiment that it is “a precious invention”. And if it produces the habit of preserving copies of Letters; will be a blessing to mankind, especially in preventing litigious law suits.
Accept my best wishes for your health. yours affectionately
DLC: Papers of Thomas Jefferson.