REPORT OF THE PRESIDENT, 1912. 25 



devices previously used. An attempt is now being made to apply this ap- 

 paratus, which has proved completely successful on land, to the determina- 

 tion of dips on the Carnegie. 



The past year has been one of minimum sun-spot activity ; but effective pro- 

 gress has been made in many other branches of solar and stellar research 

 undertaken by the Observatory. The wide range of this 

 Solar Observatory, work may be indicated by the fact that the results of the 

 investigations of the year are summarized by the Director 

 under thirty-five different heads. The new tower telescope has been com- 

 pleted and important auxiliary apparatus has been added to the equipment 

 of the 60-inch reflector. A fire-proof office building, which will afford ade- 

 quate quarters for the staff and safety for the original records and photo- 

 graphic plates of the Observatory, has been constructed and made ready for 

 occupancy during the year. 



The 150-foot tower telescope with its spectrograph and spectroheliograph 

 has been tested and found to be quite up to expectations. The 60-inch re- 

 flector has proved increasingly effective in the wide variety of work under- 

 taken with it. Between forty and fifty new spectroscopic double stars have 

 been found; and amongst the many stars whose radial velocities have been 

 measured is one which surpasses all others hitherto observed, its velocity 

 being about 150 miles per second. 



Two eminent Research Associates, namely, Professor Kapteyn, of Gro- 

 ningen, and Professor Stormer, of Christiania, have taken part in the work 

 of the Observatory during the year. Professor Kapteyn, who has served in 

 this capacity for several years previously, has been of great service to the 

 department, especially in the planning of a program of work with the 60- 

 inch reflector, so that it may yield a maximum return alike for problems of 

 stellar distribution and stellar development. Professor Stormer, who is one 

 of the highest authorities concerning auroras, has sought to determine espe- 

 cially the connection of these phenomena with the sun. Of their connection 

 with the sun and with the earth's magnetism there is little doubt, and the 

 recent demonstration of the atomicity of matter in general and the atomic 

 nature of electricity in particular may be confidently expected to lead to 

 distinct advances in our knowledge of these phenomena in the near future. 



The laborious task of shaping and testing the glass disk for the proposed 

 100-inch telescope has proved a disappointment in showing that this disk, 

 which was accepted provisionally from the makers several years ago, will 

 not answer the requirements. At this writing it appears possible that some 

 expedients may be adopted to overcome the instability of this disk; but the 

 probability that it may be made to work satisfactorily is small. In the mean- 

 time the makers of such large disks have not succeeded in making one of 

 sufficient uniformity in density. In view of these difficulties the Director is 

 disposed to try a thinner disk if one can be found possessing the requisite 



