BILiLIOGRAI'IIY OF IIERSCHEL's WKl riXGS. r).S7 



Herscliel, "W".: Syxopsis ok tuk \Vrhix(;s of— Continued. 



JL. D. Vol. p. 



i805 '15 236 Si/mptoms of paralliulic Motions. 



Three sorts of motions cxplainoil by Fi<j. 1, Plate VII. 



237 The parallactie, the real, and the apparent motions. 



238 Since a motion of the sun will occasion parallactic motions of the 



stars, these again must indicate a solar motion. To a.scertain 

 whether parallactic motions exist we must choose the brightest 

 stars which are most afVeetcd by solar motion, they being probably 

 the nearest to the snu. 



238 Wo distinguish parallactic from real motions by the direction of 



the motion. If a solar motion exists all parallactic motions will be 

 opposite to it; real motions will be dispersed indiscriminately to 

 all parts of space. 



239 The point towards which the sun moves is the apex of solar motion; 



the opposite point is the parallactic centre. 



240 Table I. Ten positions of the solar apex from hrst magnitude stars. 



241 Fifteen positions from fainter stars stated. 



242 Changes in 'he })osUlon of double Stars. Among the 'j'o stars which I 



have given, the changes of more than half appear to be [due to a 

 solar motion]. 

 242 Incongrnitij of proper Motions. 



242 Sidereal occultation of a small Star. 



As far as we can judge at present the vanishing of the small star near 

 d Ci/gni is only a parallactic disappearance. A real motion would 

 also explain it. 

 244 Direction of the Solar Motion. 



243 When -we are in search of an apex for the .solar motion, it ought to be 



so fixed as to be eqnally favorable to every star. * * * Our aim 

 should be to reduce the proper motions of the stars to their lowest 

 quantities. 

 249 Table II of the direction and quantity of the apparent motion of six 

 stars, supposing the sun to move towards ?. Uerculis. 



251 Table III of the angles of the parallactic motion with the parallel; 



and Tal)le IV, juigles of the apparent with the parallactic motion. 



252 Table V. Quantities and sum of the least n^al Motions. 



253 Assuming the apex of solar motion to be in R. A. 270= 15', N. P. D. 



54° 45', Table VI is computed: it is similar to Tables III, IV, V. 



254 Assuming the apex R. A. 245° 52' 30", N. P. D. 40^ 22', Table VII 



[like Table VI] is calculated. 



255 Although the great proper motions of Arrtarns, Procyon, and Sirius 



are strong indications of tlieir being atfected by parallax, it is not pro- 

 bable that their apparent changes are entirely due to solar motion. 

 251) Observation shows that proper motions do exist : we should choose 

 that apex which will take away more real motion than any other, 

 or we should put the apex in R^ A. 245° 52' 30", N. P. D. 40= 22'. 



1805 95 272 Ohservations on the singular Figure of the planet Saturn. By William 

 HERSCriEi., LL. D., F. R. S. Read June 20, 1805. 



272 [Brief account of the particularities of the system of Saturn.'] 



2T2 There is a singularity left which distinguishes the figure of Saturn 

 from that of all the other placets. In 177G I perceived that the 



273 body of Saturn was not round. In 1781 I found it was flattened at 

 the poles more than Jupiter. In 1789 I measured the polar and 

 equatorial diameters, and prepossessed with the idea of its being 

 spheroidical I [paid no attention to other diameters]. 



