DEPARTMENT OF MERIDIAN ASTROMETRY. 211 



of the equator will be harmonized. In this way it is hoped that we may- 

 be able to b'ing about a better standardization of star positions 

 from pole to pole. 



STELLAR WAVE-LENGTHS. 



Mr. Albrecht has continued his study of stellar wave-lengths. 

 Wave-lengths have been computed for all measures M^hich were deemed 

 suitable in Publications of the Lick Observatory, Vol. IX, Part II. 

 The immediate use for these wave-lengths was twofold: (1) to test, 

 for the measures of Dr. Palmer and Professor Wright, the variations 

 of wave-length as a function of stellar type which had previously been 

 published, and (2) to discuss these variations with special reference 

 to the distinction between the giant and the dwarf stars. 



For the first test the results are quite definite, the measures of Dr. 

 Palmer and of Professor Wright for certain lines showing variations 

 of wave-length with type which are very similar to those previously 

 found, principally for the measures of Albrecht. The second test 

 could be only partially completed at this time, due to the fact that for 

 the present only an inadequate separation of the stars in this list into 

 the giant and dwarf classes is possible. However, Vv'^ith the aid of 

 Russell's rule for the individual assignment of stars to the giant and 

 dwarf classes on the basis of stellar proper-motions, it was shown 

 that the published curves of variation of wave-length with type per- 

 tain to the giants, being based overwhelmingly on giants. Only a 

 moderate amount of revision will be required for these. For the de- 

 termination of the curves for the dwarfs there will be required (a) 

 additional stellar parallaxes for the stars in the above list, and (b) a 

 detailed study of the spectra of a specially selected list of known 

 dwarfs. At Professor Frost's suggestion the published measures on the 

 standard velocity stars were also tried. However, it w^as found that 

 the dwarf stars are not at all represented in this list. Preliminary 

 reports on the above investigation have been made at the last two 

 meetings of the American Astronomical Society. 



SYSTEMATIC CORRECTIONS TO THE PRELIMINARY GENERAL CATALOGUE. 



Mr. Roy, assisted mainly by Mr. Jenkins and Miss Buffum, has 

 discussed the systematic corrections for most of the catalogues issued 

 since the publication of the Preliminary General Catalogue and has 

 determined their weights. The results, which are now in press, will 

 furnish those who desire proper-motions in advance of their definitive 

 determination and publication with the material from which they 

 may derive approximate results. The systematic corrections derived 

 from those catalogues, of a more or less fundamental nature, indicate 

 a definite correction to the system of the Preliminary General Cata- 

 logue, as was anticipated, though the agreement among the catalogues 

 is not wholly satisfactory. 



