162 Aafmnomkal and Nautical Collections, 



angle, given by the previous computation, or added to it, 

 according to the relative situation of the angles, will give 

 the parallactic orbital angle, formed by the orbit with the ver- 

 tical circle. 



Example. In the case of the occultation of y ^, since the 

 moon passes the meridian of Paris on the night of the 8th of 

 February, at 14" 5^, it is obvious that she will be in the east 

 at 11", and that the depression by parallax will accelerate 

 the occultation. We therefore calculate the altitude for 10" 

 53^^ 18^ the time of conjunction, and for 9" 53^ 18^ Now, 

 the moon's right ascension, in the former case, is 171° 58' 1", 

 or 11" 27^ 52^ in the latter 171° 30' 9", or 11" 26^^ 1^ : the 

 sun's 21" 28^' 26^ and 21" 28"" 16^ respectively : the differ- 

 ences 10" 0^ 34^ and 10" 2^' 15^ added to the sun's horary 

 angles, make 20" 53^^ 52^ and 19" 55^33^ W., or 3" 6"^ 8^ 

 and 4" 4"^ 27^ E., for the moon's horary angles : and her de- 

 clinations are 51' 19' and 1° 6' 6" N. Then from the Re- 

 quisite Tables, XVI., we have 



N.S. 46399 Alt 27 38 42 N.S. 33243 Alt. 19 25 



L. sec. Alt .05264 .02543 



sin H. A. 46° 32' 9.86080 L. sin 61° 7' 9.94229 



cos lat 9.81835 9.81835 



sin P. A. 32° 38' 9.73179 37° 40' 9.78607 



Now the moon being east of the meridian, the vertical circle 

 passes upwards to the west of the circle of declination, and 

 downwards to the S. E., so that the parallactic angles must be 

 subtracted from 62° 2' the angle S.E. of the moon's orbit, thus. 



