£38 On the Motion of the Sun and Solar Si/sf CTTt^ 



have examined, there are 15 that do not reach two-tenths of 

 a second : (^ Virginis moves seventy-seven hundredths, 

 and a. Cygni only six. But it will be shown, when the 

 direction and velocity of the solar motion come to be ex- 

 plained, that these kind of iiicongruities are mere parallac- 

 tic appearances ; and that there is so general a consistency 

 among the real motions of the stars, that Arcturus is in 

 no respect singled out as a star whose motion is far beyond 

 the rest. 



By giving this remark a place among the reasons for ad-^ 

 mitting a solar motion, it is not intended to lay any parti- 

 cular stress upon it ; for it may be objected that our idea 

 of the congruence or harmony of the celestial motions can 

 be no criterion of their real fitness and symmetry. But 

 when such discordant proper motions as those I have men- 

 tioned in stars of no very different lustre are under consi- ■ 

 deration, and may be easily shown to be only parallactic 

 phgenomena, the method by which this can be done must 

 certainly appear eligible, and, when added to many other 

 inducements, will throw some share of weight into the 

 scale. 



Sidereal Occultalion of a small Star. 



Of nearly the same importance with the former argu- 

 ment is the account of the occultation of a small star by a 

 large one, which 1 have given in my last paper. When 

 the solax motion has been established, we shall prove that 

 the vanishing of the small star near S Cygni, as far as we 

 can judge at present, is only a parallactic disappearance. 

 It must be granted that a real motion of the large star would 

 also explain the same phpenomenon ; but then again, this 

 star must be supposed to move towards the very same pa- 

 rallactic centre which the changes in the position of other 

 double stars point out j and this cannot be probable. 



Direction of the Solar System. 



From what has been said, I believe the expedience of 

 admitting a solar motion will not be called in question ; 

 our next endeavour therefore must be to investigate its 

 direction. 



To return to the before-mentioned intersections of the 

 arches, in which the proper motions of the stars are per- 

 formed, I shall begin by proving that when the proper mo- 

 tions of two stars are given, an apex may be found, to which, 

 if the sun be supposed to move with a certain velocity, the 

 two given motions may then be resolved into apparent 



changes. 



