DEPARTMENT OF MERIDIAN ASTROMETRY. 187 



already been dealt with by Dyson on the basis of the two-stream 

 hypothesis, and by Beljawsky using the ellipsoidal hypothesis. Both 

 of these methods involve the consideration of position-angle alone. 

 Therefore, the present investigation, which employs both position- 

 angle and proper-motion, should be of interest. 



A diagram has been prepared on a Mercator projection, on which 

 the paths of all the stars of large proper-motion in the Preliminary 

 General Catalogue have been plotted, 20 seconds per century being 

 taken as the limiting proper-motion. Although it might have been 

 predicted a priori that there would be a strong convergence of these 

 paths in the region 6*" right ascension, 0° declination, the actual con- 

 vergence is startlingly portrayed. This would indicate that the true 

 paths of the stars of large proper-motion through space are in the main 

 very nearly parallel. This result might independently be obtained 

 if we consider the ellipsoidal hypothesis; for the method of selection 

 of the proper-motions would cut out nearly all the proper-motions 

 with the exception of those directed toward the apices of the ellipse. 



We have, then, the means of determining hypothetical parallaxes 

 for all those stars, selected as outlined, for which radial velocities 

 are given, on the hypothesis that the paths of these stars through 

 space are absolutely parallel, the direction of their vanishing-point 

 being taken as the vertex of preferential motion. In a majority of 

 cases the computed parallax should very closely approximate the 

 true parallax, since the deviation of the paths of the stars chosen 

 from true parallelism will seldom be sufficient to seriously affect the 

 computed parallax. 



The charted paths of the apparent motions show several sharp con- 

 vergents, one being almost exactly that of the Taurus group. These 

 indicated convergents will be investigated for possible group motion. 



COOPERATION. 



It is pleasing to record that the growing spirit of cooperation so 

 manifest among astronomers of to-day has led Professor George C. 

 Comstock to volunteer the aid of the Washburn Observatory in the 

 observation and reduction of a hst of about 3,200 stars of 61f9 or 

 brighter, included within a zone extending from +30° to — 21?5 

 dechnation. These stars comprise all the miscellaneous stars on our 

 observing list lying between the given limits and within the chosen 

 hmit of magnitude, the term "miscellaneous" referring to those 

 stars whose positions are less determinate than the positions of the 

 stars in the Preliminary General Catalogue. These stars will be 

 observed differentially, ^-he system of the Preliminary General Cata- 

 logue serving as a basis. They will also be observed at Albany. 

 The two independent determinations of the positions of these stars 

 at approximately the same epoch will lend more weight to the de- 

 termination of their positions and proper-motions than could be 



