[8] 



grove, or lather its site, is 4,759 feet above the level of the 

 sea, an elevation where, though the heat of the six mid-day 

 hours in June and July is 80^ and upwards, the nights are 

 cool; and as Professor Whitney remarks, " during ordinary 

 years, . . . the flanks of the Sierra are well covered '' 

 [with snow] down to 4,000 feet above the sea during mid- 

 winter months, and a heavy body of snow lies on the passes 

 until May, or even June." So after the snow has meltecb 

 up to and above the altitude or site of the grove, the atmos- 

 phere is cooled for a long period afterwards by the snow^ 

 clad slopes and the unmelted masses of snow upon the'"'- 

 higher flanks of the Sierra beyond. 



In the consideration of all the factors which suscffest 

 themselves, and which no doubt are more or less operative 

 or interoperative, the least perceptible, though perhaps 

 the most important, is that of compensation, which modifies 

 or neutralizes what at first appear to be conspicuous and 

 dominating influences. 



What is above presented, it should be understood, is 

 simply hypothetical, and for the purpose of awakening 

 discussion and calling attention to a most interesting sub- 

 ject; one which, if generallj^ understood, would be of great 

 practical importance. At present the data are so exceed- 

 ingly meager as to preclude anything more than specula- 

 tion, or to incite to and stimulate investigation. 



From a knowledge of the various points of inquiry herein 

 suggested, might be deduced a generalization, indicating a 

 universal and preponderating law. 



Berkeley, Cahfornia, Feb. 10, 1882. • t 



: I 



[Note. Portions of the foregoing were read before the California^ 

 Academy of Sciences, December 5, 1881 . It has since been revised and^ 

 materially modified and expanded.] 



1-. 



