Thomas Jefferson Papers

From Thomas Jefferson to Robert R. Livingston, 8 August 1790

To Robert R. Livingston

New York Aug. 8. 1790.

Dear Sir

I duly recieved your favor of the 1st. inst. and have withheld acknoleging it in hopes of finding time to consider it thoroughly. But this hope advancing before me, like my shadow, I must hasard thereon the ideas which occur extempore. I think it ingenious, well worth trying, and that probably it will lessen the friction. One consideration occurs to me. Suppose it the case of the tub mill, with it’s pivot armed with wood as you propose and turning in a vessel of mercury, instead of running on a pivot and ink as usual. A cylinder of wood 2. feet long and containing 2. cubical feet, must be of 13½ inches diameter. The pivot then will be a compound one, the central part of iron running on the iron bottom, suspended by an annulus arc of wood of 144 square inches—the area of a section of the iron part. This annulus arc resting on a surface of mercury, and turning on it, is really a part of the pivot, and, tho, the body on which it turns being fluid, the friction will be small, yet considering that it will act from 6¾ inches from the center of motion, down to (suppose) ½ inch, it’s effect may become sensible. I join with you in thinking the friction on the curve surface of the cylinder will be small, and on the whole think it worth an experiment, and will be glad to know it’s issue if you try it.

Finding that you amuse yourself mathematically, I inclose you a report of that nature made to Congress on the subject of measures and weights.—Be so good as to present me respectful-[ly] to Mrs. Livingston and to be assured of the esteem & attachment with which I have the honour to be Dear Sir your most obedt. & most humble servt.,

Th: Jefferson

PrC (DLC). Enclosure: Report of the Secretary of State, on the subject of establishing a uniformity in the weights, measures and coins of the United States (New York, Childs & Swaine, [1790]).

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