146 



Sierra Club Bulletin. 



cerned. For the observations in detail and an exhaustive 

 discussion of the question, the reader is referred to Lick 

 Observatory Bulletin No. 169, by Dr. W. W. Campbell. 



With regard to the weather records obtained, we must 

 hurry over the record, which may some time be published 

 in full elsewhere. The weather was clear from July 8th 

 until August 1 8th, when there was a thunder-storm with 

 four inches of snow. On August 19th there was another 

 thunder-storm with three inches of snow. Fair weather 

 followed until August 26th, when severe thunder-storms 

 occurred. On August 28th there were hailstorms, 

 snow-storms, thunder-storms at intervals. During every 

 night of our stay, freezing temperatures occurred and 

 on five consecutive nights the temperature fell to 26° F., 

 or even lower. The mid-day temperatures were about 

 50° F. 



We had no instruments for recording the direction and 

 velocity of air movement. One of the most interesting 

 meteorological features of the mountain and indeed of the 

 whole section, is the prevalence of uprising currents. Ulti- 

 mately we hope there will be proper instrumental means 

 for detecting and recording the flow and counterflow of 

 the air over the peak. There were also marked changes 

 in short intervals in the amount of water vapor present. 

 Our humidity records^ which were continuous throughout 

 the week and which we believe to be the first records of 

 such character ever made at an elevation exceeding 10,000 

 feet, show variations in humidity ranging from 5 per 

 cent to 98 per cent. During mid-day hours the humidity 

 would rise as a rule to above 80 per cent, while be- 

 tween 2 A. M. and 5 A. M. extremely low humidities were 

 recorded, ranging from 3 to ii per cent. 



One other feature remains to be mentioned ; that is the 

 electrification of the air. There must have been tremend- 

 ous potential differences between the cloud masses and the 

 boulders on top of the mountain. But this is only one 

 of many lines of research which ought to be undertaken 

 on the summit of Whitney. 



