l\)6 COSMOS. 



the stars may be changed from such a variety .of causes, con» 

 sidering that amazing distance at which it is certain some 

 of them are placed, it may require the observations of many 

 ages to determine the la-v^'s of the apparent changes even of 

 a single star ; much more difficult, therefore, it must be to 

 settle the laws relating to all the most remarkable stars." 



After the time of Bradley, the mere possibility, and the 

 greater or less probability, of the movement of the solar sys- 

 tem, were in turn advanced in the v/ritings of Tobias Mayer, 

 Lambert, and Lalande ; but William Herschel had the great 

 merit of being the first to verify the conj ecture by actual ob- 

 servations (1783, 1805, and 1806). He found (what has 

 been confirmed, and more precisely determined by many later 

 and more accurate inquiries) that our solar system moves to- 

 ward a point near to the constellation of Hercules, in H. A. 

 260° 44', and N. Decl. 26° 16' (reduced to the year 1800). 

 Argelander, by a comparison of 3 1 9 ^tars, and with a refer- 

 ence to Lmidahl's investigations, found it for 1800 : E,. A. 

 257° 54''1, Decl. +28° 49'-2 ; for 1850, R.A. 258° 23'-5, 

 Decl. +28° 45'-6. Otto Struve (from 392 stars) made it to 

 be for 1800 : E.. A. 261° 26'-9, Decl. +37° 35'-5 ; for 1850, 

 261° 52'-6, Decl. 37° 33'-0. According to Gauss,=^the point 

 in question falls within a quadrangle, whose extremes are, 

 R, A. 258° 40', and Decl. 30° 40'; U. A. 258° 42', Decl. 

 + 30° 57'; U. A. 259° 13', Decl. +31° 9'; K. A. 260° 4', 

 Decl. +30° 32'. 



It still remained to inquire what the result would be if 

 the observations were directed only to those stars of the south- 

 ern hemisphere which never appear above the horizon in Eu- 

 rope. To this inquiry Galloway has devoted his especial 

 attention. He has compared the very recent calculations 

 (1830) of Johnson at St. Helena, and of Henderson at the 

 Cape of Good Hope, with the earlier ones of Lacaille and 

 Bradley (1750 and 1757). The resultf for 1790 was R. A. 

 260° 0', Decl. 34° 23' ; therefore, for 1800 and 1850, 260° 

 5', +34° 22', and 260° 33', +34° 20'. This agreement with 

 the results obtained from the northern stars is extremely sat- 

 isfactory. 



If, then, the progressive motion of our solar system may 

 be considered as determined within moderate limits, the 



* In a letter addressed to me. See Schura., Astr. Nackr., No. 622, 

 %. 348. 



t Galloway, on tlie Motion of the Solar System, in the Phtlos. Tr<iJt» 

 met. for 1847, p. 98. 



