MOttON OF THE SUlf(,' 



by folar motion ; which points out the brighteft ftars as moft 

 proper for the purpofe ; for any ftar may have great real mo- 

 tion, but to have great parallaftic motion it muft be in the 

 neighbourhood of the fun. 



Parallaclic may be diftingui{hed from real motions by their 

 directions: for, if a folar motion exift, all paralla6tic ones 

 will tend to a point in oppofition to the dirediion of that mo- 

 tion ; but real motions will be indifcriminateiy difperfed. 



Under thefe difiindions, the proper motions of the fiars, if 

 the fun be not at reft, will be parallactic, or compofed of real 

 and parallaftic; the latter cafe conftituting the apparent mo- 

 tion of the ftar. 



Dr. H. next defcribes the meeting of the arches arifing from 

 a calculation of the proper motions ot the 36 ftars in Dr. Maf- 

 kelyne's catalogue on a celeftial globe, of which ten were 

 made by ftars of the firft magnitude, about the conftellation 

 Hercules.; beyond thefe there was no appearance of any other 

 than a promifcuous filualion of interfedions. — Of the inter- 

 fefting points, that towards which the fun moves is denomi- 

 nated the apex of its motion ; and as the ftars will then have a 

 paralladtic motion towards the oppofite point, it has received 

 the appellation of a paralla6lic centre. 



m 



The parallaaic 

 motions are di- 

 rededtoapoint. 



and will com- 

 bine with the 

 real (angular}. 



Dedufllon of 

 the paraliaGk- 

 centre from ohf, 

 on many ilar<i. 



InterfeCling points. 



Right Afcen (ion. 



Polar diftance 

 North. 



Taba 

 lated 

 re- 



fuifs. 



I. Sirius and Arflurus, in the mouth of ? 

 the Dragon - - - jf 



o 



255 



/ // 

 39 50 



o 

 3d 



41 Si 



2. Sirius and Capella, near the follow- 1 

 iiig hand of Hercules - - / 



275 



9 



32 



64 



21 48 





3. Sirius and Lyra, between the hand"! 

 and knee of Hercules - - J 



272 



23 



58 



58 



23 24 





4. Sirius and Aldebaran, in the follow- 7 

 ing leg of Hercules - - j 



263 



25 



38 



44 



39 47 

















5. Arclurus and Capella, N. of. the pre- ) 

 ceding wing of the Swan ■.■ j 



290 







58 



32 



7 23^ 

















6. Arflurus and Aldebaran, in the neck! 

 of the Dragon * - - J 



267 



2 



19 



33 



57 20 





7. Ardurus and Procyon, in the pre- 7 

 ceding foot of Hercules - j 



235 



3 



13 



46 



21 34 





8. Capella and Procyon, S. of the fol- 1 

 lowing hand of Hercules - j 



272 



51 



49 



73 



7 56 





9. Lyra and Ptocyon, preceding the fol- 1 



lowing llioulder of Hercuies y 



10. Aldebaran and Procyon,' in fhe | 

 breaft; of Hercules - - C 



266 



46 



49 



66 



48 11 





.'260 



1. 



29 



60 



59 34 





As 



