_Occultations of Venus._—An occupation of this planet by the Moon appears to have been recorded by the Chinese on March 19, 361 A.D. Tycho Brahe witnessed a similar phenomenon on May 23, 1587. Mœstlin observed Venus occult Regulus on Sept. 16, 1574; and on Oct. 2, 1590, this planet appears to have passed over Mars. Visible occultations of Venus are somewhat rare; they usually occur in daylight. A phenomenon of this kind was witnessed on Dec. 8, 1877, over all the W. part of the United States; and Prof. Pritchett, of Missouri, says:—“The interest taken in it was shared alike by the educated and the illiterate, and even by children.” The evening was cloudless, and many persons noted the time of disappearance of Venus as seen by the unassisted eye. With a 12½-inch refractor, power 275, Prof. Pritchett noted that “when the bright limb of Venus was within 8″ or 10″ of the Moon’s dark limb, a border of wavering light, several seconds in width, seemed to precede the planet. Its general effect was such as to place in doubt the moment of external contact.” A full description of this event, and of the partial occultation of Venus on Oct. 12, 1879, is given in No. 1 of the ‘Publications’ of the Morrison Observatory, Missouri, U.S.A.
Venus is said, by the Arabian astronomer Ibn-Jounis, to have occulted Regulus on Sept. 9, 885 A.D.; and Hind has examined the observations, by means of Le Verrier’s tables of the Sun and planets. He finds that on Sept. 9 in the year mentioned, at 16h 43m mean time, Venus approached the star within 1′·7; so that to the naked eye the latter would appear to be occulted, being overpowered in the glare of the planet.
[28] This period was probably derived erroneously by Bianchini. It includes 25 periods of 23^h 22^m, which corresponds with the times of rotation by Cassini and others given in the table.
[29] Schröter’s final result. In 1788 he had derived a period of 23^h 28^m from observations of faint dark spots, and in 1789-91 irregularities in the S. horn of Venus gave him a period of 23^h 20^m 59^s.
Appearance of the planet.—Period &c.—Phase.—Surface Configuration.—Charts and Nomenclature of Mars.—Discovery of two Satellites and of Canal-shaped markings.—Summary of Observations.—Rotation of Mars.—Further Observations required.—Changes on Mars.—The two Satellites.—Occultations of Mars.