178 REPORTS ON INVESTIGATIONS AND PROJECTS. 



Miss Lasby has devoted the greater part of her time to stellar spectra, 

 having measured and reduced 630 spectrograms during the year. About 550 

 of these were taken with the Cassegrain spectrograph and the remainder with 

 the focal plane instrument. In continuation of the investigation of the solar 

 rotation Miss Lasby has measured and reduced 18 photographs each cover- 

 ing 6 points of latitude. About 3 months was employed in the measurement 

 of laboratory photographs taken by Mr. Gale of the spectrum of the electric 

 arc and spark under pressure. Miss Lasby has also given some time to com- 

 putations connected with the construction of tables designed to facilitate the 

 reduction of stellar spectra. 



Miss Smith has continued during the year her work upon spectrohelio- 

 graph plates. This has included the determination of the areas of the 

 calcium flocculi upon 204 negatives, making the reduction complete up to 

 February i, 191 1. The curves showing the fluctuations of the areas of the 

 flocculi and so indicating the variations in solar activity have been drawn to 

 August 20, 1910. Miss Smith has measured, in addition, 269 prominence 

 plates, completing the reduction of this series to June 18, 1911. Prints have 

 been made of about 2,500 negatives, including all calcium and hydrogen 

 spectroheliograms and direct photographs of the sun taken between April 

 1908 and June 191 1. These have been classified and arranged in book form 

 for purposes of reference in investigations of sun-spot and flocculi structure. 



Miss Ware has been engaged during the greater part of the year in the 

 reduction of solar spectra obtained by Mr. St. John. The majority of the 

 photographs are related to a determination of the wave-lengths of the H and 

 K lines in the spectrum of the chromosphere. Miss Ware has also measured 

 over 100 plates in connection with the investigation of the Evershed effect in 

 sun-spots, and has made a series of determinations of the wave-lengths of 

 the oxygen lines in the a group of the solar spectrum on the international 

 system. A considerable number of reductions, related for the most part to 

 the work in stellar photometry, have been carried out by Miss Ware during 

 the year. 



The classification and reduction of stellar spectrograms has formed the 

 larger part of Miss Waterman's studies during the year. About 600 photo- 

 graphs taken with the Cassegrain and focal plane spectrographs have been 

 measured and reduced and the types of spectra represented by them have 

 been determined. Miss Waterman has also devoted a considerable amount 

 of time to the construction of a set of tables by means of which the constants 

 of reduction for the Hartmann interpolation formula may be determined for 

 any plate by simple inspection. Miss Waterman resigned from the Comput- 

 ing Division July I, 1911. 



Miss Martha Renner, who was appointed to the Computing Division Feb- 

 ruary I, 1911, has given her entire time, with the exception of that required 

 for the investigation of the screw errors of one of the small comparators, to 

 the measurement and reduction of photographs relating to investigations in 



