THE SUNS MOTION IN SPACE. 215 



sufficiently shews how precarious are the deductions of distance 

 from magnitude. 



(94a) Bakhuyzen, 1892.— In December 1892 Bakhuyzen 

 deduced the direction of the solar motion from all stars in the 

 Auwers-Bradley catalogue within 50° of the pole of the Milky 

 Way, for the plane of which Houzeau's value was accepted. 1 The 

 results for the epoch 1810 ? were 



R.A'. = 264-°6; R.A. = 260-°2; D.= +39-°5 

 From the whole of the proper motions 



R.A = 263°, D.= +32°. 

 Quoting L. Struve's results, Bakhuyzen gives finally 

 R.A. = 266°7; D. = +31°0. 



103a) Pannekoek, 1895. — In the June number of Nature, 1895» 

 a discussion of the motion of the solar system by Pannekoek is 

 referred to. 2 The deduction is made from stars of declination 

 between 0° and 20°, divided into two groups according to their 

 spectral type, and into sub-groups according to the magnitude of 

 their proper motions. The results are as follows : — 

 Spectral Type I. 



Sub-group. 



No. of 



Stars. 



P.M. 



R.A 



D. 



T. 



203 



•02 



322°-8 



+ 14°-7 



II. 



93 



•06 



304-7 



12-1 



III. 



58 



•10 



275'8 



18-3 



IV. 



48 



•34 



251-6 



33-0 







Spectral Type II. 





I. 



77 



•02 



274-6 



-2-6 



II. 



52 



•06 



280-1 



+ 35-8 



III. 



65 



•21 



268-6 



31-4 



The spectra were from the Potsdam observations. 



(105a) Tisserand, 1895 (Sept.) — In the Bulletin Astronomique 

 of September 1895, Tisserand discusses the determination of the 



1 De vraag of de bewegung van het zonnestelsel ten opzichte van de 

 sterren binnen den melkweg dezelfde is als die voor de sterren daarbuiten. 

 — Versl. d. Afd. Natuurk., 1892-3, pp. 92-93. 



2 Nature, Vol. lii., 1895, p. 135. 



