1921] Smiley: Flora of the Sierra Nev^ada of California 35 



92°, occurred on July 11, 1917 ; the day after the same temperature 

 was recorded at Fordyce and 86° at Summit, these temperatures not 

 being exceeded at these places again in the quadrennium. The same 

 date (July 11) was the year's warmest day at Bridgeport with 85°. 

 Bridgeport attains to higher maxima earlier in the year than the other 

 stations : in 3Iay, day temperatures of 82, 80, 74 and 60 are recorded 

 and in the same month lows of 26, 18, 16 and 18. The highest station 

 of the series, Tamarack, has its highest recorded temperature on 

 October 5, 1915, 92°, with a low of 22° a week later. 



The data presented in the temperature table concerning the climate 

 of Tamarack show that the local climate of high altitude valleys in 

 the Sierra conforms to the rule :*^ the diurnal range of temperature 

 at Tamarack is higher than that of any other station except Bridge- 

 port, whose exceptional climate has been referred to. The average 

 daily range at Tamarack for the year is 51.8°, which is 19.6 per cent 

 greater than the daily range at Fordyce and 38 per cent greater than 

 the range at Summit. 



In the general discussion of the rainfall of the Sierra, attention 

 was directed to the great contrast which exists between the two flanks 

 of the range. This contrast is seen within the mountains and because 

 of it the east side of the major crest-lines receives less rainfall than 

 the west slopes; Tahoe, though less than twenty-five miles from 

 Fordyce, receives less than one-half as much rain. Bridgeport 

 receives less than one-fourth as much as Tahoe and only about one- 

 tenth as much as Fordyce, though the altitude of all three stations 

 is similar and of Fordyce and Bridgeport equal. The seasonal distri- 

 bution of rainfall has been referred to and the variation seen in the 

 distribution on the eastern slope where a larger proportion of the 

 scant total falls in the summer months ; at Bridgeport 26.5 per cent 

 of the total mean annual rainfall for the years 1914-17 fell in the 

 six months from May to October inclusive ; at Fordyce in the similar 

 half-j^ear 14.7 per cent. Though the summer months have a greater 

 percentage of the total rainfall on the east slope, yet the west slope 

 receives even in summer a larger amount ; in the six months from IMay 

 to October Fordyce received, in the years 1914-17, on the average 9.77 

 inches and Bridgeport 1.95 inches. This inequality with respect to 

 summer rain is seen within the range; the east slope of the Great 

 Western Divide, west of Lake Tahoe, receives at the station of Tahoe 

 2.76 inches; Fordyce, on the west slope of the same divide, has the 

 amount mentioned above. Generally then the west slopes of the 



