THF USE OF THE CELESTIAL GLOBE. 



LECTURE X. 



THE USE OF THE CELESTIAL GLOBE, AND ARMILLARY 

 SPHERE. 



HAVING done for the present with the terrestrial globe, The /<>*- 

 we shall proceed to the use of the celestial ; first pre-* e l 

 raising, that as the equator, ecliptic, tropics, polar cir- 

 cles, horizon, and brazen meridian, are exactlj" alike on 

 both globes, all the former problems concerning the sun 

 are solved the same way by both globes. The method 

 also of rectifying the celestial globe is the same as rec- TO rectify 

 tify ing the terrestrial, viz. Elevate the pole according lt- 

 to the latitude of your place, then screw the quadrant of 

 altitude to the zenith, on the brass meridian ; bring the 

 sun's place in the ecliptic to the graduated edge of the 

 brass meridian, on the side which is above the south 

 point of the wooden horizon, and set the hour-index to 

 the uppermost XII, which stands for noon. 



N. B. The sun's place for any day of the year stands 

 directly over that day on the horizon of the celestial 

 globe, as it does on that of the terrestrial. 



The latitude and longitude of the stars, and of all other Latitude 

 celestial phaenomena, are reckoned in a very different 

 manner from the latitude and longitude of places on the **'"'* 

 earth : for all terrestrial latitudes are reckoned from the 

 equator ; and longitudes from the meridian of some re- 

 markable place, as of London by the English, and of 

 Paris by the French ; though most of the French maps 

 begin their longitude at the meridian of the island Ferro. 

 But the astronomers of all nations agree in reckoning 

 the latitudes of the moon, stars, planets, and comets, from 

 iheecliptic ; and their longitudes from the equinoctial colure* 



Note 95. The great circle that passes through the equinoctial points 

 at the beginning of Taurus and Libra, and through the voles <*f Ike 

 21. Y 



