BIBLIOGRAPHY OF HERSCHEL'S WRITINGS. 533 



Herschel, W.: Synopsis of the Writings of— Contiuuod. 

 A, D. Yoi. p. 



1783 73 ii67 Dr Maskelyne's proper motions of seven of the stars quoted, and 

 the positions of these stars plotted on Fig. 3. 



268 The motion of the sun towards the constellation of Herculen from a 



point not far from the 77th degree of right ascension to its oppo- 

 site 257th degree will account for the proper motions of these stars 

 by the single motion of the Solar System. 



269 Lalande gives the proper motion of 12 stars [table], and Fig. 4 rep- 



270 resents them projected on the plane of the equator. These stars 

 with others [named] give us 27 motions to be accounted for. Our 

 supposition of the sun's motion accounts for 22 of these, so there 



271 are but 5 exceptions, which must be resolved into the real projier 

 motions of the stars. 



272 The apparent exception of Castor considered [and the physical con- 



nection of the two components is not assumed]. 



273 The apes of the solar motion defined. 



273 As to the quantity of the solar motion I can only offer a few distant 



hints. 



274 The solar motion can certainly not be less than that which the earth 



has in her annual orbit. 

 274 Future observations will soon throw more light on this interesting 

 subject, and either fully establish or overthrow the hypothesis. 

 To this end I have already begun a series of observation upon 

 several zones of double stars, and should the result of them be 

 against these conjectures I shall be the first to point out their 

 fallacy. [Dated at Datchet, near Windsor, Feb. 1, 1783.] 



274 Postscript to the paper on the Motion of the Solar System. 



Mr. AUBERT has furnished me with Tob. Mayer's Opera Inedita, 

 which contains a catalogue of 80 stars observed by Mayer in 1756, 

 compared -with Roemer's observations of 1706. 



275 I have used these stars and left out of the list all those whose proper 



motions Mayer considers doubtful and the fourteen stars already 

 examined, and which have been shown to support the hypothesis. 

 The rest are drawn up in two tables. The first contains the stars 

 that agree with my assigned motion of the solar system. The sec- 

 ond contains those stars whose motions cannot be accounted for on 

 my hypothesis, and must therefore be ascribed to a real motion in 

 the stars themselves or to some still more hidden cause of a still re- 

 moter parallax. 

 [This phrase is explained by a foot-note, as follows:] 



276 [Foot-note.] Mr. Michell's admirable idea of the stars being col- 



lected into systems appears to be extremely well founded ; though 

 it does not, in my opinion, take away the probability of many stars 

 being still, as it were, solitary or intersystematical. Hence there may 

 be a proper motion of the whole system to which a star belongs. 

 Examples given of an inhabitant of Saturn^s fifth satellite ; or a 

 small nebula may consist of many stars and have a proper motion 

 as a system. 



277 [Foot-note.] We see, then, that while the sun is going toward a cer- 



tain point of the heavens each of the stars belonging to the sidereal 

 system, of which the sun is one, will be affected as I have shown 

 [p. 261] notwithstanding the whole system should have a real mo- 

 tion in absolute space, and change its position with respect to other 

 systems or intersystematical stars. 



