174 REPORTS ON INVESTIGATIONS AND PROJECTS. 



Miss Lasby has continued the measurement and reduction of the photo- 

 graphs of stellar spectra taken with high dispersion. Of these 26 have been 

 reduced and the results discussed both with respect to the peculiarities ex- 

 hibited by the arc and the enhanced lines in certain stars and with respect 

 to the systematic deviations shown by the lines of different elements. Miss 

 Lasby has also measured and reduced 215 low-dispersion stellar spectrum 

 plates obtained with the one-prism spectrograph in the principal focus of the 

 60-inch reflector, and a number of solar rotation, chromosphere, and labora- 

 tory photographs. 



Miss Smith has continued, as in the past, the measurement of the calcium 

 flocculi and prominence areas, and has reduced during the year 148 calcium 

 and 150 prominence plates by the weight method explained in the last report. 

 All of the plates of these series are completely reduced to February 1, 1910, 

 and the final curves showing the fluctuation of the calcium flocculi and promi- 

 nence areas have been constructed up to November 4, 1909. Miss Smith 

 has also begun, under the direction of Mr. Hale, an extensive examination 

 and comparison of direct photographs of the sun with H 2 and Ha spectro- 

 heliograms for the purpose of obtaining more definite information concerning 

 sun-spot structure and related phenomena. To avoid the inconvenience in- 

 volved in handling large numbers of plates, Miss Smith has made and used 

 for the comparison paper prints which have been collected in volumes, each 

 volume showing the complete history, so far as recorded, of each of the spots 

 or spot groups studied. Fifteen of these, comprising some 700 prints, are 

 complete at present, and the tabulation of the data resulting from this com- 

 parison has been finished. 



The prints used in this investigation have proved so convenient for rapid 

 examination and comparison that it is proposed in the future to make similar 

 prints for all direct photographs and spectroheliograms as they are obtained. 



Miss Ware has been engaged mainly in the measurement of solar and 

 stellar spectra. The stellar-spectrum work has included the measurement 

 and reduction of several high-dispersion photographs as well as a consider- 

 able number of the low-dispersion plates of the fainter stars. Recently she 

 has measured a large number of solar spectrum negatives for the determina- 

 tion of the absolute wave-lengths of the H and K lines at various points on 

 the solar disk and in the chromosphere. The work forms part of an exten- 

 sive investigation by Mr. St. John of the circulation of the calcium vapor in 

 the neighborhood of spots and spot-groups, as well as in the general solar 

 atmosphere. Miss Ware has also carried on the difficult work of determining 

 the number of stars present upon the photograph of one of the globular star 

 clusters. 



Miss Waterman's time has been devoted mainly to the study of stellar 

 spectra, some 250 low-dispersion plates having been measured and reduced, 

 and over 400 classified according to type of spectrum. In addition she has 

 measured some laboratory photographs of spectra taken under pressure, and 



