it was distant 10′ 2′′. On 4 different occasions between May 3 and 11, 1761, Montaigne, at Limoges, saw what he believed to be a satellite of Venus. It presented the same phase as the planet, but it was not so bright. Its position varied, but its diameter appeared equal to 1th that of the planet. The following extract is from the Dictionnaire de Physique, a French work published in 1789. "The year 1761 will be celebrated in astronomy in consequence of the discovery that was made on May 3 of a satellite circulating round Venus. We owe it to M. Montaigne, member of the Society of Limoges, who observed the satellite again on the 4th and 7th of the same month. M. Baudouin read before the Academy of Sciences of Paris a very interesting memoir, in which he gave a determination of the revolution and distance of the said satellite. From the calculations of this expert astronomer we learn that the new star has a diameter about that of Venus, that it is distant from Venus almost as far as the Moon is from the Earth, that its period is 9d 7h, and that its ascending node is in the 22nd degree of Virgo." Wonderfully circumstantial! In March 1764 several European observers, at places widely apart, saw a supposed satellite. Rödkier, at Copenhagen, on March 3 and 4, saw it: Horrebow, with some friends, also at Copenhagen, saw it on the 10th and 11th of the same month, and they stated that they took various precautions to make sure there was no optical illusion. Montbaron, at Auxerre, on March 15, 28, and 29, saw the satellite in sensibly different positions P. This is the plaintiff's case, if I may be pardoned for using such an expression: on the other side it can only be said that no trace of a satellite has ever been found by any subsequent observer with larger telescopes. And with the care bestowed on Venus by Sir W. Herschel and Schröter during so many years, it is difficult to understand that, if a satellite existed, they should not have seen it at some time or other . P Scheuten says he saw a satellite accompany Venus across the Sun during the transit of 1761. See Ast. Jahrbuch, 1778. Reference may also be made to a letter by Lynn in The Observatory, vol. x. p. 73, March 1887. The question of the existence of a satellite of Venus is very fully discussed, Lambert combined all the observations in a very tolerable orbit, but, as Hind points out, notwithstanding its agreement with the observations, there is one fatal objection to it-if it were correct, the mass of Venus would be 10 times greater than what other methods show it to be, namely 10 that of the Sun. Encke gives Tor's, Littrow 103871 Mädler 0171 Le Verrier 1150, and Newcomb 103000. There are several methods of ascertaining this quantity, the most obvious of which is based on the disturbing influence exerted by Venus on the Earth's annual motion. 211 Venus has ever been regarded as an interesting and popular planet, and it is somewhat remarkable that it is the only one whose praises are sung by the great Greek bard, who thus apostrophises it: “Εσπερος, ὃς κάλλιστος ἐν οὐρανῷ ἵστατει ἀστήρι.” This refers to it as the Evening Star, but elsewhere in the Iliad" we meet with it in its other function of the 'Ewopópos, to which the Latin Lucifer corresponds. Some have thought, and perhaps not without reason, that it is the object referred to in Isaiah xiv. 12. The earliest recorded observations of Venus date from 686 B.C., and appear on an earthenware tablet now in the British Museum *. Claudius Ptolemy has preserved for us in his Almagest many observations of Venus by himself and other astronomers before him, at Alexandria in Egypt. The most ancient of these observations is dated in the 476th year of Nabonassar's era and 13th of and from a new standpoint, in a paper by M. Bertrand in L'Astronomie, vol. i. p. 201, August 1882; but it does not seem worth while to go more fully into the subject here. And see also M. Stroobant's very interesting Etude sur le satellite énigmatique de Vénus published at Brussels in 1887. His researches show that in almost all cases stars which can be identified were mistaken for a satellite; in a few instances where the identity is doubtful possibly a minor planet was seen; and in one instance possibly it r Bode's Jahrbuch, 1777. Homer, Iliad, lib. xxii. v. 318. u Lib. xxiii. v. 226. Pythagoras (or, according to others, Parmenides) determined the identity of the two "stars." * Month. Not., vol. xx. p. 319. June 1860. the reign of Ptolemy Philadelphus, on the night of the 17th of the Egyptian month Messori, when Timocharis saw the planet eclipse a star at the extremity of the wing of Virgo. This date answers to 271 B.C., Oct. 12 A.M." As this was not a telescopic observation, it and all others recorded before telescopes came into use, are open to this uncertainty, that the two objects may merely have been in juxta-positon so as to have appeared as one without actual super-position taking place. The recorded occultation of Mercury by Venus on May 17, 1737, was no doubt an occultation in the strict sense of the word. The interesting discovery of the phases of Venus is due to Galileo, who announced the fact to his friend Kepler in the following logogriphe or anagram a : "Hæc immatura, a me, jam frustra, leguntur.-oy." “These things not ripe [for disclosure] are read, as yet in vain, by me." Or, as another interpretation has it "These things not ripe; at present [read] in vain [by others] are read by me." The "me" in the former case being the ordinary reader; in the latter, Galileo. This, when transposed, becomes "Cynthiæ figuras æmulatur Mater Amorum." "The Mother of the Loves [Venus] imitates the phases of Cynthia [the Moon]." The letters 'o y' are, it will be observed, redundant, so far that they cannot be made use of in the transposition. To the mariner, owing to its rapid motion, Venus is a useful auxiliary for taking lunar distances when continuous bad weather may have prevented observations of the Sun. In computing the places of Venus the tables of Baron De Lindenau, published in 1810, were long in use, but they have now y Hind, Sol. Syst., p. 32. It was one of the objections urged to Copernicus against his theory of the solar system that if it were true then the inferior planets ought to exhibit phases. He is said to have answered that if ever men obtained the power of seeing them more distinctly, they would be found to non è vero, è ben trovato." a Opere di Galileo, vol. ii. p. 42. Ed. Padova, 1744. been superseded by those of Le Verrier, for amongst other causes of error there existed a long inequality (first suspected by Sir G. B. Airy about 1828, and fully expounded in 1831) affecting the heliocentric places of the Earth and the planet to a very sensible amount. This inequality goes through all its changes in about 239, and when at a maximum displaces Venus by 3" and the Earth by 2", as viewed from the Sun. b Phil. Trans., vol. cxviii. p. 23, 1828; vol. cxxii. p. 67, 1832. CHAPTER VI. THE EARTH. ✪ "O let the Earth bless the Lord: yea, let it praise Him, and magnify Him for ever."-Benedicite. Period, &c.-Figure of the Earth.- The Ecliptic.-The Equinoxes. -The Solstices.Diminution of the obliquity of the ecliptic.—The eccentricity of the Earth's orbit.-Motion of the Line of Apsides.-Familiar proofs and illustrations of the sphericity of the Earth.-Foucault's Pendulum Experiment.-Mädler's tables of the duration of day and night on the Earth.—Opinions of ancient philosophers. -English mediæval synonyms.—The Zodiac.-Mass of the Earth. THE HE Earth is a planet which may perhaps be said to be in all essential respects similar to Venus and Mars, its nearest neighbours; but as we are on it, it is needless to point out the impossibility of treating of it in the same way as we treat of the other planets. It revolves round the Sun in 365d 6h 9m 9'63, at a mean distance of 92,890,000 miles. The eccentricity of its orbit amounting to oo1679, this distance may either extend to 94,450,000 miles or diminish to 91,330,000 miles; and these differences involve variations in the light and heat reaching the Earth which will be represented by the figures 966 and 1033, the mean amount being 1000. The Earth is not a sphere, but an oblate spheroid; that is to say, it is somewhat flattened at the poles and protuberant at the |