140 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 65 



For the reasons given above, the absolute humidity, table 8, was also probably 

 higher than normal. The mean was 3.5 grams per cubic meter, the mean 

 maximum 4.2 at 4 to 5 p. m., and the mean minimum 2.7 at 4 a. m. The abso- 

 lute maximum was 6.2 at 7 p. m. of the 7th and the absolute minimum 0.6 at 

 midnight of the 12th. 



Table 9 gives roughly the average wind velocities. Dial readings of the 

 anemometer were made at the times indicated by stars. The figures between 

 these stars represent average velocities for the intervals between readings. 

 The mean for the entire period was 3.0 m. p. s. That at Pikes Peak for the 

 same time of year was 6.0 m. p. s. This difference may be due partly to the 

 fact that Pikes Peak stands out in the open, whereas Mount Whitney is 

 surrounded by peaks nearly as high as itself, and also to the greater proximity 

 of Pikes Peak to the cyclonic storm paths of the United States. The prevail- 

 ing wind direction was southeast, but directions ranging between south and 

 northeast were frequently observed, and a southwesterly wind prevailed during 

 the blizzard of August 9. 



In table 10 may be found the state of the weather for the period, together 

 with notes on storms, kinds of clouds, and miscellaneous phenomena. 



FREE-AIR OBSERVATIONS AT MOUNT WHITNEY, CAL. 



The place from which balloon ascensions were made was about 60 meters 

 to the northwest of the summit of Mount Whitney and about 10 meters below 

 it. This was the only spot on the mountain that was fairly level and free 

 from jagged surface rocks. While the balloon was being filled with gas it 

 rested on a large piece of canvas to protect it from rocks and snow. The 

 gas, compressed in steel cylinders, was furnished by the Signal Corps of the 

 United States Army. A hand reel was used for. reeling the wire in and out. 

 Readings of the psychrometer, aneroid barometer, and anemometer were made 

 with the aid of a pocket electric flash lamp. 



Ascensions were made on only three nights, August 3, 4, and 5, and were 

 begun immediately after sundown. On all other nights the weather was either 

 too windy or too stormy. The balloon was allowed to take as great an altitude 

 as possible and was then kept out until the wind aloft had increased to such 

 an extent that it was necessary to reel in. 



Table 11 contains the tabulated data for the three records obtained, and in 

 figures 11 and 12 are plotted the temperature and absolute humidity gradients, 

 respectively ; the slight changes with time at the higher levels in each ascension 

 are not plotted ; only the ascent and descent proper. On August 3 and 4 these 

 elements diminished with time by nearly the same amounts at all upper levels 

 as at the surface. There was but little wind during these nights. On August 

 5, however, there was a fairly high northeast wind aloft and the temperature 

 and humidity changed very little with time. The change with altitude in 

 temperature was greater and .in absolute humidity less than on the other 

 nights. 



