PrC (DLC); at foot of first page: “Bishop Madison”; faint, torn along margin of first page, several phrases illegible; figures in brackets supplied from TJ’s notes on Zach’s letter (see below).

Person here: see TJ to Andrew Gwin, 24 Mch. 1798.

Franz Xavier von zach, an astronomer whose observatory near Gotha was under the patronage of the Duke of Saxe-Coburg, had sent some of his published works to the American Philosophical Society, which acknowledged receipt of the books at a meeting of 17 Nov. 1797. TJ did not attend that meeting but presided over another on 19 Jan. 1798 at which Zach, an active disseminator of astronomical data who regularly exchanged information with American scientists, was elected to membership (DSB description begins Charles C. Gillispie, ed., Dictionary of Scientific Biography, New York, 1970–80, 16 vols. description ends , 14:583; APS description begins American Philosophical Society description ends , Proceedings, 22, pt. 3 [1884], 262, 266; Greene, American Science description begins John C. Greene, American Science in the Age of Jefferson, Ames, Iowa, 1984 description ends , 135, 142, 154–5). Robert Patterson, who in 1797–1798 was a curator of the society and had recently served as one of its secretaries, was the recipient of a letter from Zach that has not been found but evidently accompanied the books sent by the German astronomer (APS description begins American Philosophical Society description ends , Proceedings, 22, pt. 3 [1884], 235, 246, 266). TJ made notes on “de Zach’s lre to mr Patterson” but did not record its date. The notes include the table of the right ascension and declination of Polaris and the other data from Zach that TJ reported to Bishop Madison in the letter above. TJ identified Zach as “Director of the Observatory at Seebourg in Saxony” (MS in DLC: TJ Papers, 232:41533; entirely in TJ’s hand; undated; endorsed: “Astronomy”; see notes 1–2 below).

The observatory at lilienthal, overseen by Johann Hieronymus Schroter, held some of the finest equipment in Europe and was a center for astronomical research (DSB description begins Charles C. Gillispie, ed., Dictionary of Scientific Biography, New York, 1970–80, 16 vols. description ends , 12:226). Zach publicized Schröter’s recent discovery in Allgemeine Geographische Ephemeriden, Verfasst von einer Gesellschaft Gelehrten und herausgegeben von F. Von Zach, H.S.G. Obristwachtmeister und Direktor der herzoglichen Sternewarte Seeberg bey Gotha, 1 [1798], 131–3, XVI-XVII.

Observation of the polar star: Andrew Ellicott had published tables and other data on the position of Polaris in APS description begins American Philosophical Society description ends , Transactions, 3 [1793], 116–18, and as a pamphlet, Several Methods by Which Meridional Lines May be Found with Ease and Accuracy: Recommended to the Attention of the Surveyors in the United States (Philadelphia, 1796). See Evans, description begins Charles Evans, Clifford K. Shipton, and Roger P. Bristol, comps., American Bibliography: A Chronological Dictionary of all Books, Pamphlets and Periodical Publications Printed in the United States of America from … 1639 … to … 1820, Chicago and Worcester, Mass., 1903–59, 14 vols. description ends No. 30385. By declaring that the table in the above letter represented the true position of the pole star, TJ probably meant that Zach’s figures were more accurate than earlier data, not that the table took into account all variables affecting the star’s apparent location in the sky, such as aberration and nutation. Zach’s great compendium of star tables, the Tabulae Speciales Aberrationis et Nutationis, was not formally published until 1806, but portions were printed earlier. Apparently one of those incomplete versions was the work that the American Philosophical Society received from Zach in November 1797. Zach continually refined his data, and the figures for the pole star in the 1806 edition do not precisely match those in the letter above (Zach, Tabulae Speciales Aberrationis et Nutationis in Ascensionem Rectam et in Declinationem …, 2 vols. [Gotha, 1806], 1:76; Connaissance des Tems, Year 8 [1799–1800], 400; Year 10 [1801–1802], 326).

For his 1770 calculation of the longitude of Philadelphia, expressed in the letter above as hours, minutes, and seconds west of the meridian of the Paris Observatory, the renowned European mathematician and scientist Leonhard euler drew on data from the transit of Venus between the earth and the sun in June 1769. Euler collected other calculations of the city’s longitude as well, including one of 5 hours, 9 minutes, and 55 seconds west of Paris that had been derived using observations of the movements of Jupiter’s satellites and was reported to the APS description begins American Philosophical Society description ends in 1769 by Presbyterian minister and avid astronomer John Ewing, who long served as provost of the University of Pennsylvania. Bishop Madison and Ewing had been contentious rivals in 1784, when they represented Virginia and Pennsylvania respectively on a commission fixing the boundary between the two states (Leonhardi Euleri Opera Omnia [Leipzig and Berlin, 1911], ser. 2, vol. 30:153, 225–6; APS description begins American Philosophical Society description ends , Transactions, 1 [1771], 55–9, 88; 6 [1809], 359; Royal Society of London, Philosophical Transactions, 59 [1769], 170–93, 228–40, 273–80, 327–58, 374–8, 407–31; Francisco de [i.e., Franz Xavier von] Zach, Tabulae Motuum Solis Novae et Correctae ex Theoria Gravitatis et Observationibis Racentissimis Erutae … [Gotha, 1792], 29; Brooke Hindle, David Rittenhouse [Princeton, 1964], 253–4; DAB description begins Allen Johnson and Dumas Malone, eds., Dictionary of American Biography, New York, 1928–36, 20 vols. description ends , 6:236–7).

At a meeting presided over by TJ on 2 Mch. 1798 the Philosophical Society agreed to pay Samuel Lewis’s bill of $5.24 for his work filling the diplomas of 31 new members over the previous eight months (bill in PPAmP, in Lewis’s hand, with Samuel H. Smith’s endorsement of the society’s action, TJ’s signature, and Lewis’s receipt of payment on 6 Mch. 1798; APS description begins American Philosophical Society description ends , Proceedings, 22, pt. 3 [1884], 268).