186 G. H. KNIBBS. 



(92) Ristenpart, 1892. — Ristenpart compared the zones of 

 Bessel with Becker's (Berlin) northern zones, 1 the interval being 

 about a half century, in connection with an elaborate investigation 

 of the constant of precession, and of the solar motion. Ristenpart 

 concluded that the Galaxy consists of two intersecting planes, the 

 coordinates of the principal and secondary poles, in 1850 being: 2 



Pole of Primary plane of Galaxy R. A. = 196-°6, D. = + 18-°7 

 ,, Secondary „ 191*1, 55-8 



While Houzeau gave as the result 192-2, 27*5 



In developing his equations he took account of Schonfeld's 

 hypothesis of a rotation in the plane of the Milky-Way. Dividing 

 the stars into four classes as follows, and abandoning the hypothesis 

 of a rotation he obtained the results : — 



Class. ££ P.M. R.A. D. 



I. 85 over 0-251 302-2 +32°-4 



II. 221 over 0-158 286-3 29 8 



III. 148 under 0-158 294-7 24-8 



IV. 4,565 over 0-1 294-3 28-2 



A second calculation, including that hypothesis gave — 



Class I. R.A. 289°-9 D. + 33-3 



II. 280-3 33-9 



III. 267-3 28-4 



IV. 276-5 27-0 



While a third, with a modification of the hypothesis, gave — 



Class I. R.A. 290°-6 34-4 



II. 2816 36-9 



III. 266-7 33-3 



IV. 281-2 41-2 



The results shew that when a term (h) depending on the rotation 



is introduced 



R.A. = 284°, T>.= +30° 

 but if neglected, 



R.A. -281°, D.= +39° 



1 Untersuchungen iiber die Constante der Praecession und die Beweg- 

 ung der Sonne im Fixsternsysteme. — Veroff. d. Grossh. Sternw. zu 

 Karlsruhe, Heft, iv., pp. 197 - 288, 1892. 2 Ibid. p. 258. 



