118 Mr. J. Y. Bucliauau. On Rapid Variations of [May 31, 



sina, and is very easily accessible. It had been raining heavily in the 

 night, so that in the early morning the air was rather cool; but the 

 following observations made before starting up the mountain will 

 show how rapidly the temperature was beginning to rise. 



8.0 A.M Dry bulb, 10'4 ; wet, 9 0< 2. 



9.10 14-8; ll-4. 



10.0 17-0. 



At 10 A.M. I started up the mountain, following the excellent path 

 which leads to the summit. 



In the following table the temperatures observed at various 

 stations are entered along with corresponding ones observed in the 

 porch of the Hotel Reseg at Pontresina. 





Excepting in the first interval the rate of fall of temperature 

 between Pontresina and the station on the mountain is less than 1 

 per hundred metres. At the summit the mean temperature of the 

 dry bulb was 10'75, and of the wet bulb 6'45, whence we have the 

 vapour tension 4'5 mm. and the relative humidity 47. The weather 

 was of the same kind as in the valley, abnormally warm, and the air 

 very dry. 



Eeceived May 31, 1894. 



The thermometer which was used in these observations was not 

 very sensitive, and when it was broken I could only replace it by one 

 which was considerably less so. They were, therefore, of no use for 

 determining rapidly varying temperatures. The method indicated 



