Thomas Jefferson Papers

To Thomas Jefferson from Dennis Griffith, 8 October 1801

From Dennis Griffith

Elk Ridge Landing October 8th. 1801


An Idea has occured to me, that it is possible to ascertain the Longitude of places in the Northern Hemisphere, when the necessary preparatory Tables are formed, in as simple manner, (or nearly so) as the Latitude. It appears to me that if the nightly positions of the pointers, in their revolution round the north Star, can be accurately fixed, & a Table formed thereof similar to that of the Sun’s daily declination, as used in the Seaman’s assistant, the desired effect might be obtained by observation with a Quadrant. It will perhaps be necessary to ascertain the relative distances of the pointers to the polar Star & of the same to each other, & to combine the nightly observation of them, with the last preceeding daily observation for the Latitude; hence, something more will depend upon reckoning & calculation, than in taking the Latitude & the operation, perhaps, from other circumstances will be a little more complex.

I have observed that the Sun’s declination on the meridian is the source of our Latitude & an Idea of a revolutionary body round a fixed (or nearly so) object would give as just an Idea from observation of our easting & westing, as the other does of our northing & southing (when the observations are combined). Relying upon your character I have been emboldened to write to you on the subject, with full confidence that if there is any thing in the suggestion worth attention, that it will not be lost. I am not master of a sufficient degree of Science to pursue the investigation, if worthy, you will put it into possession of some person that is. If not I am well assured in my mind that you will pardon the intrusion, that the perusal of this may make upon your public functions.

I am with the most sincere respect yr. obt.

D Griffith

RC (PPAmP); endorsed by TJ as received 15 Oct. and so recorded in SJL; endorsed in an unknown hand: “Non est inventor”; also endorsed for the American Philosophical Society.

Dennis Griffith exchanged letters with TJ in 1793, shortly before publishing a map of Maryland (Vol. 26:798; Vol. 27:53–4). After being read at the APS description begins American Philosophical Society description ends on 7 May 1802, Griffith’s communication was referred to a committee made up of Robert Patterson and Benjamin Henry Latrobe. The committee was discharged on 18 June (APS description begins American Philosophical Society description ends , Proceedings, 22, pt. 3 [1884], 323, 325; John Vaughan to TJ, 8 May 1802).

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