To John Adams from Pelatiah Webster, 7 June 1787
From Pelatiah Webster
Philada. 7 June, 17871
Sir.
Mr. John Churchman of This City Thinks he has Discover’d a Method by Which the Longitude at Sea or Land may be Ascertaind. by one Simple Observation in Any part of The World,2 & Which is certainly Very Easy if the Great fact on which the whole depends can be well Ascertain’d, & Which I think not Improbable, ’tis this, Viz that the Magnectic needle has two poles one north 13.°56′ from the N. Pole of the Earth the other South, abt. 18.o from the S. Pole of the Earth, Which Poles have a Constant Rotation from West to East, & form their Revolutions in 463 Years, & 344 days i.e. abt. 47′
Minutes of a degree in a Year, that the True place of these poles may be Ascertain’d, & Tables of the Same calculated for Every Given Minute of Time, & of Course that the line or point of no Variation for Any place & the Time, may be Easily found, & of Course the Angle of Variation & Radius will always be Attainable, & the Difference of Latitude of the place of observation & that of the Magnetic Pole will be one Side of the Triangle Necessary to be found,— he further Tells me that by a Long Attention to Halley’s Theory of the Magnet, & the various Observations of Cook & many other Navigators in their Very Long Voiages, & by comparing them all together, it Appears that the Lines of Variation When continued on the Globe from Whatever part of the Earth Never fail to Meet at the same place or Point Where the pole of the Magnet by his Tables was found to be at the times of Observation,— This is A Matter of Such Weighty consequence, & the Truth or falsehood of his plan or Method may be so Easily Examin’d that I think it will work a Very carefull Attention & Enquiry, & the Author is undoubtedly intitled to the honours & Rewards of the Discovery, if his Great fact is found True on Sufficient proof, Mr Churchman is a Young man of Good Character, of a Good Country Education but Not a Genl. Acquaintance with any course of Liberal Learning, At his Desire I hereby Recomend him & his plan (Wc. he Sends to You,) to Your favorable Notice & Patronage— I have Nothing New or Important to inform You but the Convention of the States Are now Sitting here, with a View to mend our Articles of Confederation or form a New System, Which perhaps is much Easiest of the Two, but how they will succeed God knows, our confusions Are Very Great,
I have the honour to be / Hond. Sir. / with all Esteem & Respect / Your most Obedt. / & very huml servt.
Pela’ Webster
RC (Adams Papers); addressed: “His Excellency / John Adams Esqr. / American Minister at the / Court of Great Brittain / London”; internal address: “his Excelly John Adams Esqr.”; endorsed by AA2: “Mr Churchman / june 7th / 1787—”; notation: “To 2/13.”
1. Pelatiah Webster (1726–1795), Yale 1746, was a prominent Philadelphia merchant, political economist, and pamphleteer during the American Revolution (vol. 4:311; ).
2. On 16 Feb., surveyor John Churchman Jr. (1753–1805), of Nottingham, Md., presented a paper to the American Philosophical Society outlining his theory, drawing from the work of English astronomer Sir Edmond Halley, that observing the magnetic needle’s variation would determine longitude at sea. After a society committee reviewed and discredited Churchman’s theory on 2 March, he revised and resubmitted it on 20 April, with no effect. Churchman also wrote directly to JA on 6 June (Adams Papers), enclosing his address, and he appealed to Thomas Jefferson for help in proving his method but ultimately failed. A 1794 London edition of Churchman’s Magnetic Atlas is in JA’s library at MB (Amos Day Bradley, “John Churchman, Jr. of Nottingham,” Bulletin of Friends Historical Association, 43:20, 25 [Spring 1954]; , 22:148–149, 150, 153; ; , 11:397–399; ).