BiBLiOGiiAPiiY OF iikksciiel's wraxiNGS. 589 



Herschel, W.: i^YXorsis cf tuk Wi;itings of— Coiitinnod. 



A.D. Vol. P. 



180G 9t> 21') TdhL- X contains tlic icmiU of calculation of tlic jjcrnianeut <iuauti- 

 ties. It lias six columns: (1) gives the star's name; (2) its pro- 

 portional distance; (3) apparent motion; (4) Direction witli tlio 

 parallel; (;'>) Direction with the parallactic motion; (G) Velocity. 

 [There are 3G stars. ] 

 21G Plate IV, Fig. 1 and Fig. ^.^, exhibits columns 3, ■!, and 5 graphically. 



Fig. 2 and Fig. 4 give the velocities. 



217 Eetnarlcs on the sidereal Motions as then <^'''^ rejyreseniedfrom Observation. 



Fig. 1 (from observation) shows that there must be some physical 



cause which gives a bias to the directions in which the stars are 



moving. Discussion of Figs. 2, 3, 4. 



219 The Solar Motion and its direction assiiincd in the first part of this paper 



are confirmed hij the Phenomena attending the observed motions of 30 stars. 



221 Trial of the method to obtain the Quantitij of the Solar'Motion hi/ its Hank 



among the sidereal Velocities. 



222 Calculations for investigating the Consequences arising from any proposed 



Qmntitij of Solar Motion and for delineating them by proper Figures. 



223 Table XI contains 5 columns: (1) name of star, including the sun ; 



(2) Parallactic Motion; (3) Real Motion; (4) Parallactic Angle; 

 (5) Velocity. 



224 Figs. 5 and G illustrate Table XI. 



224 Eernarks that lead to a necessary examination of the Cause of the sidereal 



Motions. 



225 A motion of the stars may arise from mutual gravitation or from an 



original projectile force. Both these causes act in the solar system. 

 225 The similar direction of the motion of a group of stars may be as- 

 cribed to their similar projectile motions. 



227 Considerations of the attractive Power required for a sufficient Velocity of 



the sidereal Motions. 

 The mere attraction of neighboring stars acting upon each other 

 cannot bo the cause of proper motions. Sirius and the Sun from 

 that cause would approach yearly by less than 0".000000005 to an 

 eye at the distance of Siriits and supposing Its parallax 1 . 



228 A centre of attraction must then be assumed, and original projectile 



229 motions must be supposed. 



229 The centre of attraction may be one mass or a group. 



230 Or it may be a union of groups; like two clusters 12= apart which 



are near the line of the solav motion. 



231 The Milky Way will furnish centres of attraction. 



231 Independent of the solar motion, the action of distant centres of 



attraction will be required to explain the proper motions of stars. 

 If the Sun be at rest Arcturus moves 2" a year; and this must be 

 due to a projectile motion and the attraction of far distant centers 



232 Determination of the Quantity of the Solar Motion. The --^assigned 



to the solar motion is a perfect medium among the [3G] sidereal 

 velocities [which have been considered.] -, ^ • n ^ 



233 The quantity of the solar motion is such that to an eye placed at right 



angles to L direction, and at the distance from Sirius, at would be 

 annually 1".116992. ■ . n 



234 Concluding Pemarks and Inferenees. [Objections c^^^-;^^;'^'^- 1 



234 When a general knowledge of the proper motions of all the stars of 

 the li 2d, and 3d magnitudes has been obtained, the present cal- 

 culation can be repeated by the same methods. 



