56 REPORTS ON INVESTIGATIONS AND PROJECTS. 



ASTRONOMY. 



REPORT OF DIRECTOR OF THE SOLAR OBSERVATORY, MOUNT 



WILSON, CALIFORNIA.* 



By George E. Hale, Director. 



I have the honor to present my first formal report on the Solar 

 Observatory. In view of the fact that the work of the Expedition 

 for Solar Research from the Yerkes Observatory has been continued 

 by the Solar Observatory', this report covers the entire period of our 

 occupation of Mount Wilson, beginning with February 29, 1904. 



The circumstances leading up to the establishment of the Solar 

 Observatory have been stated elsewhere f and need not be repeated 

 here. Sufiice it to say that a grant of $10,000. made by the Exec- 

 utive Committee of the Carnegie Institution in April, 1904, rendered 

 it possible to bring the Snow telescope of the Yerkes Observatory 

 to Mount Wilson in the summer of 1904. As a study of the atmos- 

 pheric conditions had given rise to belief that the site would prove 

 a very advantageous one, warranting occupation for a considerable 

 period of time, a lease of a large tract of land on the mountain was 

 at once negotiated. The Carnegie Institution had not then decided 

 to establish an observatory of its own, and the future was therefore 

 uncertain. Accordingly the lease was taken bj'^ myself personally, 

 but a new lease has since been executed in the name of the Carnegie 

 Institution. The property belongs to the Pasadena and Mount 

 Wilson Toll-road Company, and I desire to put on record my sense 

 of obligation to the officers and controlling stockholders of this com- 

 pany, Messrs. J. H. Holmes and W. R. Staats, of Pasadena, to whom 

 we are indebted for liberal and courteous treatment. The lease, 

 which comprises a large tract (not yet completely surveyed) of the 

 best land on Mount Wilson, not only involves no charge for the use 

 of the property, but establishes restrictions of great importance on 

 the adjoining land of the toll-road company. These restrictions, 

 as fully set forth in the lease, seem to obviate completely such inter- 

 ference with the observations as might be caused by smoke, electric 

 lights, vibrations from machinery, and other similar disturbances. 

 The lease also contains other advantageous concessions, including 

 one-half the water rights on Mount Wilson, free use of the toll trail 

 to the valley, etc. The seemingly unique advantages of Mount 

 Wilson, in atmosphere, topographical features, and proximity to an 



* Grant No. 217. ^I5o,ooofor building observatory and maintenance for 1905. 

 (For preliminary report see Year Book No. 3, pp. 155-174.) 

 t Contributions from the Solar Observatory, Nos. i and 2. 



