^2 MOTION OF THE SUN» 



Confirmation by As a fuftber Confirmation that the paralladic motion tnay 

 other ftars, be perceived in the motion of the brighteft ftars. Dr. H. ex- 

 amined the interfe61ions made by the proper motions of fomc 

 large flars of the next order, with the arches in which the ftars 

 of the fir ft magnitude move, and found 15 which gave iimilar 

 rcfults with (he former 10, in pointing out th? fame part of the 

 heavens as a parallaflic centre. 

 This rcfuU co«. Changes in the pofition of double ftars indicate the fame re- 

 firmed by doufcis f^^l^^ 3„^ ,^,^^, therefore be more ehgibly afcribed to the effe6l 

 of paraUax, than to admit of feparate motions in different 

 ftars ; for, if the aUerations of the angle of pofilion were 

 owing to a motion of the largeft ftar in each fet, fuch motions 

 muit, HI contradiction to probability, tend nearly to one par- 

 ticular part of the heavens. This argument derives its vali- 

 dity from the fame fource with the former, viz. the parallactic 

 motions ot at leaft 28 more ftars pointing out the fame apex ot 

 9 folar motion, by their direction to its oppofite parallactic 

 centre, 

 and by the bar- The Incongruous mixture of great velocity and extreme 



mony of the fio^wnefs in the proper motions of the ftars of the fame magni- 

 propcr motions . "^ ' " 



deduced from it. tude> is removed by the confideration of parallax from the 



folar motion ; and it will be feen that there is a general con- 

 ftdency in their motions. The fame obfervation is alfo appli- 

 cable with refped to the fidereal occultation of a fmall ftar 

 in the Swan. 

 Jnveftlgation of Dr. H. concludes from the foregoing premifes, that the ex- 

 the direaion ot pediencv of admitting a folar motion will not be queftioned, 

 the fun's pioper f^ J . „■ . .. «. rr , - • 



motion. and proceeds to inveftigate its direction. He begms by 



proving, that when the proper motions of two ftars are given, 



an apex may be found, towards which if the fun be fuppofed 



to move with a certain velocity, the two given motions may 



. be refolved into apparent changes arifing from ftdereal pa- 



An apex or pa- rallax, tlie ftars remaining perfectly at reft. For we rauft 



raiiaftic center j^^^j admit more motions than are fufficient to account for the 



IS deduced from 



the apparent obferved changes in the fituation of the ftars ; and itvvoiild be 



-notions of two wrong to have recourfe to the motions of two ftars, when 



nars, fuppofed ,,.,,. , i /- «• • r t ^ 



to have no real *"^t Ot the lun alone maybe lumctent to account tor both i 



motion. which confideration would be a fufficient inducement for fix- 



ing at once on the calculated apex as well as on the relative 

 diflances afligned to the two ftars, could other proper motions 

 be, with equal facility, refolved into fimilar parallactic ap- 

 pearances : but, when a third ftar does not direct towards tijp 

 5 fame 



