REPORT OF EXECUTIVE COMMITTEE. 89 



and the 12-inch and 40-inch refracting telescopes have been used as 

 heretofore. 



The measurement of the magnitudes of the ninth and twelfth 

 magnitude stars in the northern Rumford fields has been completed. 

 There are still lacking nineteen sets to complete the work on the 

 sixteenth magnitude stars with the 40-inch telescope. Work has 

 been continued on a selected list of twenty-five variable stars, deter- 

 mining the light curves and the magnitude of the comparison stars. 

 All the fields of the variable stars have been photographed with the 

 24-inch reflector, insuring a correct identification of the comparison 

 stars and furnishing material for the determination of the photo- 

 graphic magnitudes. Other investigations include the photometric 

 measurement of ninth to twelfth magnitude companions of some of 

 the Struve double stars, made at the request of Professor Comstock, 

 the measurement of standard stars in the Pleiades, the calibration 

 of the wedge photometer b}' means of a polarizing photometer, etc. 



In addition to several papers published in the Astrophysical Journal 

 and the Astronomical Journal, Mr. Parkhurst has completed the 

 manuscript of a large memoir, which includes a complete discussion 

 of his investigations in stellar photometry and his observations of 

 variable stars. This will be submitted to the Carnegie Institution 

 for publication. 



Solar Investigations. — ^The reduction of the Kenwood Observatory 

 photographs of the sun, undertaken by Mr. Fox last year, has been 

 completed by him. This yields the first determination of the rotation 

 period of the sun as defined by the motion of the calcium flocculi. 

 The new method of measurement emplo3^ed, which involves the use 

 of a globe upon which the photographs are projected, has proved 

 to be very rapid and sufiicientlj' precise for the purpose. The rota- 

 tion periods of the calcium flocculi in different latitudes do not differ 

 greatly from the results obtained by Stratonoff for the faculae. The 

 manuscript describing this investigation has been completed and 

 will be submitted to the Carnegie Institution for publication. 



Since completing these reductions in January, 1904, Mr. Fox has 

 been in charge of the Rumford spectroheliograph, which is employed 

 with the 40-inch refractor of the Yerkes Observatory. With this 

 instrument he has obtained a large number of photographs of the 

 calcium and hydrogen flocculi and of the prominences. He has also 

 made photographs of the solar disk through certain dark lines of 

 the solar spectrum, and has devoted special attention to a comparison 

 of the photographs of the faculae with photographs taken with the 



