82 



RELATIONS PERTAINING SIMPLY 



[BOOK I. 



Further, it is evident, that in I. and II., in order that I X and b /? may be 

 had in seconds, for If, must be taken the mean parallax of the sun in seconds ; 

 but in III., for R, must be taken the same parallax divided by 206265&quot;. Finally, 

 when it is required to determine in the inverse problem, the place free from 

 parallax from the place affected by it, it will be admissible to use J, /, b, instead 

 of r, A, ft, in the values of the parallaxes, without loss of precision. 



Example. Let the right ascension of the sun for the centre of the earth 

 be 22046 44&quot;.65 = 31, the declination, 15 49 43 / .94 ft the distance, 0.9904311 

 = r: and the sidereal time at any point on the surface of the earth expressed 

 in degrees, 7820 38&quot;==X, the elevation of the pole of the point, 4527 57&quot; = ^, 

 the mean solar parallax, 8&quot;.6 = R. The place of the sun as seen from this point, 

 and its distance from the same, are required. 



log R 0.93450 log.fi 1 0.93450 



logcos^ 9.84593 log sin B 9.85299 



C.logr ...... 0.00418 



C. log cos p .... 0.01679 



log sin (l L] . . . 9.78508 



C.logr 0.00418 



C. lo sin 6 0.10317 



Iog&amp;lt;7_3L) . . . . 0.58648 

 11= + 3&quot;.86 



1= 22046 48&quot;.51 



log tan B ..... 0.00706 



log cos (X L) . . . 9.89909 



log tan 6 ~. . . . 0.10797w 



6= 127 57 V&quot; 



i 6= U34644 



log sin (p 6) 



log (b- 



. . 9.77152 



. . 0.66636 n 



b fi = - 4&quot;64 

 b= 15 49 4 8&quot;. 58 



log (*_/}) .... 0.66636 n 



log cot (0 0) . . . 0.13522 



logr 9.99582 



logl&quot; 4.68557 



log(r J) 

 r // = 



. 5.48297 n 

 0.0000304 

 0.9904615 



71. 



The aberration of the fixed stars, and also that part of the aberration of com 

 ets and planets due to the motion of the earth alone, arises from the fact, that 

 the telescope is carried along with the earth, while the ray of light is passing 



