Thomas Jefferson Papers

To Thomas Jefferson from David Rittenhouse, 14 April 1787

From David Rittenhouse

Philadelphia April 14th. 1787

Dear Sir

About the latter end of June last I sent you the 2d. Vol. of our Transactions, directed to Mr. Adams at London. I afterwards found that Mr. Adams was at that time Absent; it is therefore probable that you have not yet recived it. Should it still come to hand it may give you an Opportunity of gratifying some freind. I have some hopes that the Society will publish a Small Volume next winter. I can’t however pretend to contribute much towards it as the Business of my Office, continually encreasing, not only occupies my time intirely at present, but is become almost insupportable.—We have abundance of projectors and pretendors to new Discoveries, and many applications to the Legislature for exclusive priviledges, some of them ridiculous enough. The selfmoving Boat, the Steam Boat, the Mechanical Miller, the improved Ring Dial for finding the Variations of the Needle. The Surveying Compass to serve 20 other purposes, And a project for finding the Longitude by the Variation of the Magnetical Needle. Of this I shall give you a more particular Account. The Authors first scheme was this. He supposes two invisible Globes, appendages of the Earth, to Govern the Needle and likewise greatly to influence the Tides, one having 70 or 80 Degrees North Declination and the other almost as much South, and he has Assigned the periods of their revolutions. But being told that his Globes would infallibly fall to the Earth unless Supported by an Iron Spike or something of that nature, he has discharged them and contented himself with assigning two points, one near each pole. Thro’ the Northern one, he says, pass all the Magnetical Meridians in the Northern Hemisphere, and thro’ the other all those of the Southern Hemisphere. He has determined the present situation and periodical revolution of the North point with great precission, of the other he speaks more doubtfully. In a plausible publication he proposes on these principles to find the Longitude Generally and thinks himself intitled to a public reward. I promised myself the pleasure of spending the ensuing Season at home, having been absent three Summers past. My Blessing on Miss Patty. I hope the lameness of your wrist will not long make writing difficult.

I am, dear Sir, with the greatest esteem Your affectionate friend & Humble Servant,

Davd. Rittenhouse

RC (DLC); endorsed. Recorded in SJL as received 11 June 1787.

On the project for finding the longitude, see John Churchman to TJ, 6 June 1787.

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