MOUNT WILSON SOLAR OBSERVATORY. 283 



rotation. Measures on these are for the present confined to the 

 equatorial latitudes. 



Miss West was a member of the division from October 1 to July 1, 

 during which time she gave her attention mainly to the work in stellar 

 photometry, and especially to that part relating to the Selected Areas. 

 26 plates, mostly of the richer fields, were measured and reduced, and 

 much miscellaneous computing was done. Miss West has also tran- 

 scribed regularly from the original reduction-sheets the results of 

 measures of the sun's general magnetic field used in the investigation 

 of the incUnation of the solar magnetic axis. 



Miss Wolfe has given the greater part of her time to the final reduc- 

 tion and collection of the results for the Standard Polar Magnitudes. 

 The laborious and exacting compilation of the tables for the final 

 publication of the results has been entirely in her hands. She has 

 further carried out all of the least-squares solutions, about 90 up to 

 date, relating to the investigation of the inchnation of the sun's mag- 

 netic axis, and has done much miscellaneous computing and checking 

 of results. She has also served as librarian during the absence of 

 Mrs. Longacre. 



A number of members of the division have given valuable assistance 

 in connection with the editorial work, among them Miss McClees, 

 Miss Wolfe, and Miss Richmond, and especially Mrs. Longacre and 

 Miss West. 



The hbrary, as heretofore, has been in the charge of Mrs. Longacre. 

 The accessions of bound volumes number 215: 66 by purchase, 116 by 

 binding, and 33 by gift. The total number of volumes is now 3,891. 

 The total number of pamphlets and unbound volumes is at present 833. 



CONSTRUCTION DIVISION. 



DRAFTING AND DESIGN. 



The preparation of working drawings for instruments designed in 

 part by members of the staff and in part by the Observatory draftsmen 

 has continued under the direction of Mr. Pease. As in the past few 

 years, most of the time has been devoted to the 100-inch telescope, 

 for which the following complete working drawings have been prepared: 



Declination slow motion. Plate-holder. 



Right ascension worm and mounting. Elevator engines for wind screen, cage hoist 



Apparatus for cutting worm gear. and platform. 



Gear for rotating cages. Counterweight and rope-drive systems for 



Mercury level apparatus. above. 



Edge ring for top of mirror. Dome trucks. 



Newtonian cage. Cage hoist. 



Cassegrain and coud6 cages. Right ascension quick motion. 



Drawings were also completed for the following instruments : 



Alterations of 60-foot tower telescope and Concave grating, 1-meter focus (alterations) » 



30-foot spectrograph and 150-foot tower 10-inch portrait-lens telescope, 



coelostat and second flat. 13-foot spertroheliograph. 



Cassegrain spectrograph (alterations). Laboratory arc. 



