ASTRONOMY. 77 



meridian of the second observer intersects the ap- 

 rallel of the first, and thus the parallax is compu- 

 ted as above. 



This method of finding the parallax, was applied to 

 that of the moon, by LA CAILLE, who observed at 

 the Cape of Good Hope, and LA LANDE, who ob- 

 served at Berlin, in 1751. LA LANDE, Astrono- 

 mic, torn. n. 1650. 



. 



77. Two observers being supposed, as in the 

 last article, the parallax of a star may be found, 

 by comparing it with a fixed star, (which has 

 no parallax), at the time of its passage over the 

 meridian. 



For if S be the object of which the parallax is to be 

 found, as before ; T a fixed star, that passes the 

 meridian at the same time, or nearly at the same 

 time with S ; the angles TAS, TBS, may be both 

 measured, and they are together equal to the angle 

 ASB ; because AT and BT are parallel. 



The angle ASB being thus found, the rest of the cal- 

 culation is as above. 



LA CAILLE and WARGENTEN, the former at the Cape, 

 the latter at Stockholm, employed this method for 

 finding the parallax of Mars. LA LANDE, torn. u. 

 1652 ; VINCE, vol. i. 158, 



78. If 



