ASTRONOMY. 9 



15. To find the Meridian Line, or that in 

 which the plane of the meridian intersects the 

 horizon of any place. 



Observe the altitude of a star when it is on the east 

 side of the meridian, and mark on the horizon 

 the point which is in the same vertical circle, or 

 which has the same azimuth with it. Observe the 

 star when it has the same altitude again on the 

 west side of the meridian, and mark in like man- 

 ner the point on the horizon which is in the same 

 vertical circle with it. The line that bisects the 

 angle made by lines drawn from the place of ob- 

 servation to the two points thus marked on the 

 horizon, is the Meridian Line. 



For when the altitudes of a star on opposite sides of 

 the meridian are equal, its azimuths, or the angles 

 which its verticals make with the meridian, are e- 

 qual also. 



16. The meridian and the latitude being thus 

 found, if the meridian altitude of any star be ob- 

 served, its distance from the pole, or from the 

 equator, is determined. 



a. For the altitude of the equator, or of the point 

 where the equator cuts the meridian, is known, be- 

 ing the same with the complement of the latitude 5 

 and the difference between the meridian altitude 

 of the star and of the equator is the declination of 

 the star. 



klf 



