DEPARTMENT OF MERIDIAN ASTROMETRY. 223 



equation we are able to obtain an idea of the upper limit of dw through 

 the equation 



, tsinH P , 



The second cause, designating by dy and dK the corrections to the 

 assumed pole Go, ^o leads to the condition 



E= sin H -\-cos H cos G cos Ho dy-\-cos H sin H d/c = 



from which dy and dx are derived by the method of least squares. 

 Again we form an upper limit for dw from the equations 



E+irdT+P'dp = 

 E P' 



where II' and P' are known functions of the star's motion and of the 

 corrections dy and dK. The weight of each equation £" = is taken as 



. . . . P' 



m mverse proportion to the mfluence of dp, i. e., to the coefficient — ^. 



Utihzing the 116 stars already mentioned, the following results were 

 derived. 



62 apices belong to the first plane (galaxy). 

 57 apices belong to the second plane. 

 The remaining 27 apices belong to neither group. 

 30 apices are common to both groups. 



Neglecting them, the solution for the poles of the planes gives 



1 plane (32 apices) T = 192?2=t3?3 k=+36?2±2?6. 



2 plane (27 apices) 7 = 151.3±4 .6 /c= -48.0±4.5. 



The measure of precision for dir, assuming that all the stars belong 

 to one of the two planes, is dir^ ±0''055±0T008 dp. 



Assuming a maximum error of dp = 5 km., the condition for assigning 

 the apices to the two planes allowed a maximum c?7r = 0''l. 



The detection of an apparent secondary plane of velocity distribu- 

 tion among the large proper-motion stars is interesting, and becomes 

 more significant in view of the Director's detection of an apparently 

 similar secondary plane of stellar distribution. The indication of such 

 a plane was pointed out by him at the meeting of the American 

 Astronomical Society in 1912. The pole of the plane is located at 

 right ascension 161°, declination — 35°. The plane passes within 15° 

 of the vertex of preferential motion, and is only slightly inclined from 

 perpendicularity to Gould's bright belt. 



