From Nevil Maskelyne
ALS: American Philosophical Society
Greenwich Dec. 27th. 1769
I think I desired the favor of you lately by letter, that when you wrote to Philadelphia you would desire Mr. Owen Biddle and Mr. Joel Bayley to take the trouble to determine the difference of meridians of Philadelphia and Norriton, in order to connect all the observations made by the three setts of observers together.9 I should be glad if you would also desire of your correspondents to obtain their observations of the transit of Venus &c. made at Philadelphia, in the State house square from the observers,1 and that they describe the telescopes made use of, and all circumstances of the observations, particularly in what manner they observed the contacts of the limbs2 of the Sun and Venus. I have delivered Mr. Biddle’s and Mr. Bayley’s observations to the Royal Society in your name. I am Dear Sir, Your most Obedient Servant
Turn over for the P.S.
P.S. I shall also be obliged to you to forward a request to the Philadelphia observers, that they would favor me with their observations of the late transit of Mercury Nov. 9th. and the eclipse of the moon Dec. 12th. if they observed them. I have wrote an answer to Mr. Winthrop’s letter to me which will bring with me when I come to town, and if you have any opportunity of sending [for] it soon will beg leave to trouble you with it, otherwise will dispatch it by the usual conveyance. I have communicated Mr. Winthrop’s letter, and also his observation of the transit of Mercury in 1743, to the Royal Society.
Addressed: To / Dr. Benj: Franklin / at Mrs. Stephensons / In Craven Street / In the Strand.
Endorsed: Mr. Maskelyne to Dr Franklin
9. See Maskelyne to BF above, Dec. 11, 1769; the annotation there deals with most of the points in this letter. For the Astronomer Royal see above, XI, 482 n.
1. See Evans to BF above, June 11; Pa. Chron., May 29–June 5, 1769.
2. I.e., outer edges. The reference is to the black-drop effect, which baffled eighteenth-century observers: Venus, after it had moved inside the limb of the sun, appeared to be still connected with it by a band or drop of planetary matter. See Harry Woolf, The Transits of Venus … (Princeton, 1959), pp. 148–9, 193, 195.