6G 



Motion of 



THE 



SUN'i 



Sirius 



• 



0.65437^' 



Ar6lurus 



. 



1.28784. 



Capella 



- 



0.10887 



Lyra - 



•i 



0.11281 



Aldebaran - 



. 



0.0110 1 



Procyon 



- 



0.0-1-998 



Sum - - 2.221-91 

 The reftill of this invelligation is, that by admitting a molioni 

 of the fun towards x Herculis, the annual proper motions of 

 the fix ftars alluded to, of which the fura is 5.3537", may be 

 reduced to real motions of no more than 2,2249''. 

 A more favour- The author here obferves, that although the precife place 

 able apex. j,f ^^^ j^gf^ ^^^^ jg difficult to afcertain, a more favourable one 



than that above propofed may be obtained : for, by infpeclion 

 of the figure which reprefents the quantities of real motion 

 required, when x Herculis is fixed upon, it will appear that 

 fey a regular method of approximation, the line S P may be 

 turned into a fituation, wherein all the angles of the appare^^ 

 motion of the fix flars will be much reduced; and it is evi- 

 dent that the parallactic line S P lliould be turned more towards 

 the line sa, reprefenting the apparent motion of Sirius. He 

 accordingly fries a point near the following knee of Her- 

 Its fituation. cules, whofe right afcenfion in 270''. 15'. and north polar 

 diflance 51-°. 43', fee Fiq.3, the quantities required for con^ 

 flruSing which are found by the fame method as already de- 

 fcribed in Fig. 2. By a calculation of the angles and the leafl 

 quantities of real motion, according to this apex, it appeared 

 that the annual motion of the fix ftars was reduced to 1.4594", 

 whicli (^0.7G55" lels than when the apex was x Herculis. 

 Suppofition that I" ^^^ appiOvimation to this point, it appeared, that when 

 Sirius may be the line of the paralla6lic motion of Sirius was made to coincide 



m .ft affeaed by . • ' ... - . , , n 



paraKax, as ^'^" '^^ apparent motion, a certam minimum might be eaGIy 



brightcftj obtained of the other parallactic motions. But as Sirius has 



not the greatefl proper motion, the author conceived that 



another minimum, obtained from the line wherein Ardlurus 



appears to move might be more accurate ; as this ffar from 



its great proper motion may be more afTedled by the parallax 



or Arfturuj, as arifing from the motion of the fun. He therefore chofe a point 



having the ^^j y„]y |j^ ^j^g jjj^g pf ^^^Q apparent motion of Arcturus, but 



greateft apparent ' _,. . "^ , _, 



motion. * equally favourable to Sinus and Procyon, the remaining two 



flars which have the greatefl motions. 



«'If 



