MOUNT WILSON SOLAR OBSERVATORY, 21 3 



In order to provide for the gradually increasing requirements in the way 

 of water-supply development, work will be begun this autumn on the well 

 at Strain's Camp. It seems probable, in view of the character of the springs 

 supplying this well, that a sufficient supply may be obtained by an adequate 

 increase in the size of the storage capacity of the well. 



An important piece of work during the summer was the construction of a 

 permanent metal screen on the exterior of the 60-inch telescope dome to 

 replace the canvas hitherto used. On account of heavy snow and wind 

 storms we have not found it possible to leave the canvas screen on the dome 

 throughout the winter, and in its absence the air inside the dome (on clear 

 days) becomes considerably heated on account of the direct exposure of the 

 metal roof to the sun's heat. This results in air-currents and some impair- 

 ment of the definition. It is hoped that the metal screen will be completed 

 before the beginning of the rainy season. 



The exterior of the Snow telescope house has been painted during the 

 summer and a few alterations have been made in the sheet-iron louver sec- 

 tions. A steel gutter surrounding the entire building has been added and a por- 

 tion of the floor at the southern end of the telescope-house has been replaced. 



At the request of the Smithsonian Institution the Observatory has erected 

 a 40-foot steel tower above the laboratory building on Mount Wilson, in 

 which Mr. Abbot and his associates have carried on their investigations 

 of the solar radiation. The tower is similar to the 6o-foot tower of the 

 Observatory, and may be used in the same way to support a coelostat and 

 lens in case it is desired to make studies of the radiation of different por- 

 tions of the sun's disk. An inclined track 160 feet long, supported on trestle- 

 work and provided with a small car and hoisting windlass, has been installed 

 above the Smithsonian laboratory in order to facilitate the transportation 

 of heavy instruments and building materials. 



A motor stage, operated in connection with the Mount Wilson Hotel, now 

 runs daily between Pasadena and Mount Wilson, making the trip to the 

 summit in 2^4 hours and the return trip in i^ hours. 



