Thomas Jefferson Papers

To Thomas Jefferson from Benjamin Dearborn, 8 November 1802

From Benjamin Dearborn

Washington Nov. 8th 1802


As the application of some natural principle, to the construction of a Standard of Measures, has been considered a Desideratum in Philosophic Research, the importance of the subject has induced me to spend some time in forming a Theory, applicable in practice, for obtaining a lineal standard, as nearly invariable as the case might require, or reason expect, in a state of being, where Nothing is Stationary—

Fully aware that Pleasing Theories are often Impracticable, I ever rely on them with a Diffidence, which is proportionate to the Difficulty of bringing them within the sphere of Mathematical Demonstration, and the Laws which regulate the Mechanical Powers: But, as the theory above referred to, appears to me in all its parts, to be subjected to such Demonstration, and to those Immutable Laws,—and, as pursuits of this kind, through a series of years, have given me an opportunity of knowing Pretty Accurately, how to estimate my own Theories, I feel a degree of Assurance in speaking of this.—

It consists of a Simple Time-Piece, with that part of the work which is termed the Scapement, so constructed, as to give Equal Impulse to the alternate vibrations of the Pendulum, and to perform what is commonly called the Dead Beat; that is, a progressive motion by seconds, without a recession, or what is termed by artists the Recoil. The Rod of the Pendulum will be so attached to the time-piece, as to be Easily taken out, and exchanged, and its Length as easily ascertained. The Bob of the pendulum will be divided into two equal parts of weight, either by a straight line, or by the Arc of a Circle, the centre of which is the Point of Oscillation; at this line the Rod (which will be made of Wood) may be cut off, or mark’d as most expedient, to a Degree of Exactness as great, as can be ascertained by the Eye, with or without the assistance of Glasses. The weight of the bob will act Independently of the weight of the rod, which is a necessary principle in constructing a Time-Piece for this purpose;—otherwise a Lighter rod would depress the Centre of Gravity, and a Heavier would raise it.

These few particulars are sufficient to give a general idea of the instrument—Should it ever be thought worthy of Public Attention, I would construct one on These Conditions, viz. That if it should answer the Designed Purpose, I should meet a stipulated Reward, if not, that I should loose my Labor;—the decision to be made by a Committee Previously appointed, whose Candour and Information should give them the Power of Deciding Justly—

I have the Honor to be Sr yr most obt and very hble Servt

Benjamin Dearborn.

RC (DLC); addressed: “Thomas Jefferson Esqure President of the United States”; endorsed by TJ as received 8 Nov. and so recorded in SJL.

Dearborn, who had been settled in Boston for many years and would return there, may have been staying in WASHINGTON with an eye toward becoming head of the U.S. Patent Office, a position about which he asked James Madison a week later (Madison, Papers, Sec. of State Ser. description begins William T. Hutchinson, Robert A. Rutland, J. C. A. Stagg, and others, eds., The Papers of James Madison, Chicago and Charlottesville, 1962–, 33 vols. Sec. of State Ser., 1986–, 9 vols.; Pres. Ser., 1984–, 6 vols.; Ret. Ser., 2009–, 1 vol. description ends , 4:123; Vol. 37:541).

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