According to Mr. Lalande, (in his _Astronomie_, vol. ii.) the transit of Venus over the Sun, in 1639, observed by only Messrs. Horrox and Crabtree, two Englishmen, and which was the first ever observed, was seen in consequence of a fortunate accidental circumstance. He says, that Horrox had been occupied in making calculations for an almanack, from the Tables of Lansbergius, which are much less perfect than the Rudolphine Tables: that these Tables of Lansbergius were in an error of 16′ for the latitude of Venus, while the Rudolphine Tables had an error of only 8′; but the one of Lansbergius made Venus pass on the sun in such a way, as that the transit ought to be visible; whereas the tables of Kepler represented the planet as passing below him; and thus it was, remarks Lalande, that bad tables occasioned a good observation. Relying on these tables, which Lansbergius had extolled with a confidence likely to produce imposition, Horrox prepared himself to observe that transit; and on the 24th of November, it took place at the time he expected, Venus being about half an hour on the sun when he set. He had sent on the occasion to his friend Crabtree, who was at Manchester, some miles from Hoole: and he observed the transit, likewise; though very imperfectly, by reason of intervening clouds. W. B. On the 9th of November, following, there was a Transit of Mercury over the Sun. An account of this phænomenon,—as observed at Norriton by William Smith, d. d. John Lukens, Esq. and Messrs. David Rittenhouse and Owen Biddle, the Committee appointed for that Observation by the American Philosophical Society,—was drawn up and communicated to the Society, by direction and in behalf of the Committee, by Dr. Smith: this will be found in the first volume of the Society’s Transactions. In this report it is remarked, that—“the first time that ever Mercury was observed on the Sun’s disk, was by Gassendus at Paris, October 28th 1631, O. S. and that the Transit of Nov. 9th was the fourth in that class; the two intermediate ones, each at forty-six years distance, having been observed by Dr. Halley, in 1677 and 1723.”