i8 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



clouds in the six weeks' period. Cloudiness was nearly negligible. The 

 most remarkable feature of the weather, particularly for March and 

 early April, was the lack of wind. Nearly half of the days were 

 entirely calm, and another fourth had only a light breeze. On less than 

 three per cent of the days was there a brisk wind. 



On our second visit to Mount St. Katherine, our records covered 

 the period from April 30 to May 30. During this interval the num- 

 ber of excellent and satisfactory days increased quite materially, 



LOG PYRHELIOMETER SOLAR CALORIES 

 Fig. 7. 



owing to less haze. Ten per cent of the days were lost by clouds, and 

 the windiness increased somewhat, although nearly two-thirds of 

 the days were calm or with light wind. 



Our third visit extended from June 12 to July 19, and from a 

 standpoint of weather should be divided into two separate groups, 

 the June days and the July days, for there was a marked change for 

 the better between June 30 and July i. This change seemed to be 

 permanent, for it lasted during the nearly three weeks of July in 

 which we were on the mountain. During this period the excellent 



