372 



26 



Table 13 (continued.) 



'ç3 o 



Mount Wilson effective wavelengths 



Copenhagen 

 effective 



Göttingen 



UV Zeiss- 



tripletand 



Müllerand 



Kempf 



■\asuai 



Tikhoff 



diffprpnpp 





s Si 

 DD a 



from spectra of the order 



wavelengths 

 Potsdam 

 Publ. 63 



actinometrj- 

 and Har- 

 vard vis. 



between 



425 and 



540 /i/t 



weighted 

 mean 



§3 



I ' II 



III 







I/. P I,. P 



J. P 



I/. P 



I/. P 



li. P 



h P 



J;, p 





m m-2 m m-5 



m m-2 



m m-2 



m m-2 



m m-2 



m m-2 



m m-2 



8 





•17 60 











•17 60 



27 



•06 4 -12 32 













■11 36 



29 







•01 52 











•01 52 



65 



•17 176 











•51 51 





•25 227 



108 



■19 111 





■15 106 











•17 217 



123 







•05 65 











•05 65 



165 



•24 2 





•77 61 











•75 63 



169 







•21 132 











■21 132 



182 







•41 60 





■ 







■41 60 



248 





— 03 112 



— 08 3 







•26 190 





■15 305 



260 



•14 12 





•12 84 











•12 96 



269 



•09 262 





•06 117 











■08 379 



310 







•44 120 











•44 120 



328 



•77 28 





•73 14 











•76 42 



396 







•04 133 











■04 133 



416 



•19 153 





•03 14 











■18 167 



480 



•88 6 



1^09 42 











1^06 48 



526 



•04 32 



•08 30 











•06 62 



600 



•11 8 



•09 36 











•09 44 



695 



•09 2 



•24 127 











•24 129 



724 





•63 60 











•63 60 



1088 



•29 45 





•28 36 







•12 153 





■18 234 



1158 







•07 182 











■07 182 



1164 



•96 75 





•96 42 











■96 117 



1184 







•11 108 











■11 108 



1224 



•30 18 





■32 22 











■31 40 



fore more or less arbitrary, which stars are counted as members of the group, 

 while for a number of stars with distinct different motion it may be taken for 

 certain that they do not belong to the system. In the case of the Pleiades the 

 picking out of the physical members is difficult because the proper motion of the 

 group is small and directed nearly awaj' from the sun's apex. According to the 

 PGC of Lewis Boss the mean proper motion of 12 briglit stars in the Pleiades is 

 '^'054 in the direction 158° or, applying the Kapteyn correction of + "'''■013 cos ö' 

 = "''^■012 to the proper motion in declination (B. A. X. 14), "'^■043 in the direction 

 152°. The direction from the sun's apex is 147°. It is therefore possible, that the 

 Pleiades, after correction for the sun's motion, are practically at rest in space. The 

 radial velocity calculated under this assumption is +8'^™/s in accordance with the 

 observed mean value +8''™/s± 2'""/s (m. e.) (comp. Johannes Jung, Astron. Mitt, 

 der Sternw. zu Göttingen, No. 17; 1914). If the apparent proper motion of the Ple- 

 iades is considered as entirely caused by the motion of our sun, being 19 '''"/s, the 



