all the other points of the ecliptic, have a retro grade motion, and are continually moving from Eaft to Weft, or from Aries toward Pifces, &c by which means the equinoctial points are carried further and further back, among the preceding figns of stars, at the rate of about one degree. feventy-two years, and this retrograde motion called the Preceffion, Receffion, or Retrocelli of the Equinoxes. Hence, as the fixed fta remain immoveable, and the equinoxes go back ward, the stars will feem to move more and ma Eastward with refpect to them; whence the long tudes of the stars, which are reckoned from th first point of Aries, or the vernal equinox, a continually increafing. Hence it is that the conftellations have changed the places affigned them by the ancient aftronomers: in the time of Hipparchus and the oldeft aftronomers, the equinoctial points were fixed to the firft ftars of Aries and Libra; but the figns are no longer in the fame points; and the ftars which were then in conjunction with the fu when he was in the equinox, are now a whole fign, or thirty degrees, to the East thereof: the the firft ftar of Aries is now in the portion of the ecliptic called Taurus; and the firft ftar of Taurus now refides in Gemini; and Gemini is advanced into Cancer, &c. Some fay the Zodiac conftellations Have long fince chang'd their antique ftations In Taurus now, once in the Ram. HUDIBRAS The phyfical caufe of the preceffion of the equinoxes, according to Sir Ifaac Newton, arifes from n the broad fpheroidal figure of the earth; ch itself arifes from the earth's rotation round axis; for as more matter is accumulated all nd the equatorial parts than any where elfe he earth, the fun and moon, by attracting this andance of matter, bring the equator fooner er them in every return towards it, than if re was no fuch accumulation. PROBLEMS PROBLEMS ON THE CELESTIAL GLOBE PROBLEM LIV. To find the Declination of any fixed Star. RING the given ftar to the graduated fide of the brazen meridian, and the degree over it is the declination. See Def. 1. P. 247. EXAMPLES. What is the declination of the ftar Arcturus, in Boötes-Anf. About 20 degrees North. Required the declination of the following stars: a, in Cygnus-y, in the head of Draco-a, in Caffiopeia-a, in Caftor-a, in Lyra-a, in Pegafus-, in Andromeda-a, in Orion-a, in Canis Minor-a, in Hydra-a, in Crater-a, in Centaurus, in Crofiers-a, in Canis Major-a, in the head of Pavo-a in Cetus-a, in Scorpioa, in Pifces Auft-a, in Auriga-a, in Perfeusthe Pleiades-a in Urfa Major. PROBLEM PROBLEM LV. find the right Afcenfion of the Sun, or any fixed Star. Bring the fun's place, or any given ftar, to the azen meridian, and that degree of the equator, hich is cut by the meridian, is the right afcenon required. See Def. 2. p. 147. EXAMPLES. What is the right afcenfion of the fun on the oth of March, and on the 21ft of September?nf. o and 180 degrees. What is the right afcenfion of the fun on the ollowing days : January 4-February 4-March 30-April 25May 18-June 27-July 9-Auguft 15-Septemer 7-October 22-November 18-December 2. What is the right afcenfion of Aldebaran, in Taurus?-Anf. About 65 degrees. Required the right afcenfion of the following tars : a, Vega, or Venga, in Lyra-ß, in the ead of Draco-a, in the Southern fcale of Libra , Scheat, in the leg of Aquarius-a, in Delphimusa, in Columbo Noachi-B, Rigel, in Orion's heel-B, Deneb, in the tail of Leo-ß, in the houlder of the Cameleon-B, the Eaftern ftar in Crufero-a, in the tail of Apus-the ftar in the Northern branch of Robur Caroli-a, in the Eastern horn of Aries-a, Cor Leonis, or, Regulus, in Leo, on the ecliptic-B, in the body of Urfa Major-the Hiades, in the head of Taurus-B, Seat Alfaras, in the thigh of Pegafus-Cor Caroli, between Afterion and Chara, the dogs held by Boötes. PROBLEM PROBLEM LVI. To find any Star on the Globe, by having its Decli nation and right Afcenfion given. Find the right afcenfion on the equator, an bring it to the brafs meridian; then count from the equator, on the meridian, the given declina tion, towards the pole which its name denotes and the ftar under this point will be the on required. N. B. By this problem, any ftar, planet, o other body, may be inferted on the globe, wher its right afcenfion and declination are given. EXAMPLES. What ftar has its right afcenfion 76°, and its declination 81 South ?--Anf. Rigel. Required the ftars whofe right afcenfions and declinations are nearly as follow: |