REPORT OF THE PRESIDENT, 1913. 27 



vortices, and those of other collaborators and members of the obser- 

 vatory staff, present features of special interest in the departmental 

 report. 



Favorable progress has been made in grinding the glass disk for 

 the 100-inch telescope since the source of the obstacle encountered 

 in this work was discovered about a year ago. The disk has been 

 subjected to severely critical tests, which give assurances that it will 

 meet requirements. The preparation of a 60-inch plane mirror for 

 testing the 100-inch reflector has gone on simultaneously with work 

 on the latter. The heavier parts of the mountings for the telescope 

 are now under construction by the Fore River ship yards at Quincy, 

 Massachusetts, while the foundations on Mount Wilson and the dome 

 superstructure will probably be completed as soon as the disk and its 

 mountings are ready. Allusion has already been made in a previous 

 section to the new office building at Pasadena and to the remarkable 

 success achieved in the construction of a dividing engine for ruling 

 diffraction gratings; for adequate accounts of these and numerous 

 other subjects of interest reference must be made to the Director's 

 full report. 



As indicated in previous reports, the complexity of the relations 

 which Research Associates and collaborators sustain to the Insti- 

 Work of Research ^ution is SO great as to preclude any comprehensive 



Associates and explanation within the limits allotted to an annual 

 administrative report. Their work embraces a 

 wide range of subjects and varies in its conduct from individual 

 independence to intimate collaboration with the departments of 

 research and with the division of publications. During the past year 

 more than twenty distinct fields of research have been cultivated 

 and a total of more than one hundred investigators have contrib- 

 uted to the output. Summaries of the work of associates pro- 

 ceeding independently are given by them in the current Year Book. 

 Their publications of the yesn- are cited in the bibliographical lists of 

 later sections, and the work of many collaborators is mentioned 

 in departmental reports. Attention may be called, among many im- 

 portant researches, to that of Professor H. N. Morse on the osmotic 

 pressure of solutions, now approaching completion; to the investi- 

 gations of Professor Mall and colleagues in embryology; to the comple- 

 tion of the edition of the Arthurian Romances by Dr. H. Oskar Sommer, 

 by the publication during the year of the seventh volume of this mon- 

 umental contribution to the medieval sources of modern literature; 

 to the appearance during the year of a translation into German of the 



