MOUNT WILSON OBSERVATORY. 



249 



RESEARCHES ON STARS AND NEBUL/E. 

 OBSERVING CONDITIONS. 



Records compiled by Mr. Hoge, showing the working time of the 

 60-inch telescope at Mount Wilson for the past 9 years, indicate that 

 the available observing weather for the year ending August 31, 1921, 

 was slightly above the normal amount. 



Observations were carried on during all of 192 nights and a part of 

 99 nights. On 74 nights no observations could be made on account 

 of the weather. The telescope was in use 65 per cent of the total 

 night time. The tables give statistics for each month, the conditions 

 of seeing (on a scale of 10), and the wind velocity. 



Meteorological records kept at the Observatory show a total pre- 

 cipitation for the year of 34.09 inches, which is about normal. Total 



Observing record of 60-inch reflector. 



