324 FERGUSON'S LECTURES. 



LECT. them, as Castor and Pollux in the heads of the Twins, 

 ^v^ Sirius in the mouth of the Great Dog, Procyon in the 

 side of the Little Dog, Rigel in the left foot of Orion, 

 Arcturus near the right thigh of Bootes, &c. 



These things being- premiocd, which 1 think are all 

 that the young Tyro need be acquainted with, before he 

 begins to work any problem with this globe, we shall 

 now proceed to the most useful of those problems ; 

 omitting several which are of little or no consequence. 



PROBLEM I. 



To jlnd the right ascension 96 and declination 91 of the sun, 

 or anyfoced star. 



Bring the sun's place in the ecliptic to the brazen 

 meridian, then that degree in the equinoctial which is 

 cut by the meridian, is the sun's right ascension ; and 

 that degree of the meridian which is over the sun's 

 place, is his declination. Bring any fixed star to the 

 meridian, and its right ascension will be cut by the meri- 

 dian in the equinoctial ; and the degree of the meridian 

 that stands over it, is its decimation. 



So that right ascension and declination, on the celestial 

 globe, are found in the same manner as longitude and 

 latitude on the terrestrial. 



PROBLEM II. 



To ^find the latitude and longitude of any star. 



If the given star be on the north side of the ecliptic, 

 place the 90th degree of the quadrant of altitude on the 

 north pole of the ecliptic, where the twelve semicircles 



Note 96. The degree of the equinoctial, reckoned from the begin, 

 ning of Aries, that comes to the meridian with the sun or star, is its 

 right ascension. Note by the Author. 



Note 97. The distance of the sun or star in degrees from the equi- 

 noctial, towards either of the poles, north or south, is its declination, 

 which is north or south accordingly. Ibid. 



