Chap. 14.] ACCOUNT OF THE WOELD. 47 of the others is more difficult, and has never been laid down by any one before nie CHAP. 14. (17.) — WHY THE SAME STAES HATE DITFEEEXT MOTIONS. I must first state the cause, why the star Yenus never recedes from the sun more than 46 degrees, nor Mercury more than 23^, while they frequently return to the sun within this distance^. As they are situated below the sun, they have both of them their apsides turned in the contrary direction ; their orbits are as much below the earth as those of the stars above mentioned are above it, and therefore they cannot recede any farther, since the curve of their apsides has no greater longitude^ The extreme parts of their apsides therefore assign the limits to each of them in the same manner, and compensate, as it were, for the small extent of their longitudes, by the great divergence of their latitudes^. It may be asked, wliy do they not always proceed as far as the 46th and the 23rd degrees respectively ? They in reality do so, but the theory fails us here. Por it would appear that the apsides are themselves moved, as they never pass over the sun^. When therefore they have arrived at the ^ Alexandre supposes, as I conceive justly, that our author, in this passage, only refers to the writings of his own countrymen ; Lemaire, ii. 276. 2 According to Ptolemy, these numbers are respectively 47° 51' and 24° 3' ; the modem astronomers have ascertained them to be 48° and 29°. The least elongations of the planets are, according to Ptolemy, 44° 7' and 18° 50', and according to the observations of the modems, 45° and 16° j Marcus in Ajasson, ii. 354. 3 I have not translated the clause, " quum sint divers® stellae," as, according to Hardouin, it is not found " in probatissimis codd.," and appears to have Httle connexion with the other parts of the sentence ; it is omitted by Yalpy and Lemau'c, but is retained by PoLasinet and Ajasson. 4 When these inferior planets have arrived at a certain apparent distance from the sun, they are come to tho extent of their orbits, as seen from the earth. 5 " Quum ad iUam Sobs distantiam pervencrunt, ultra procedere non possunt, deficicnte circuh longitudine, id est, amphtuduie." Alexandre in Lemaire, ii. 277.
- The transits of the inferior planets had not been obserred by the
ancients.
