18 EXPERIMENT STATION RECOED. [Vol.36 



Analyzing the records at the summit of Mount Rose and at base stations of 

 approximately 30 cold waves occurring during four years, It was found that 

 five-sixths were felt both on the mountain and in the valley, but only one-third 

 of these occurred sufficiently early on the mountain to give adequate warnings 

 below (E. S. R., 35, p. 505). 



From the snow studies the general conclusion is reached that " forests are a 

 direct protection to the snow, those trees being most effective which allow the 

 snow to reach the ground and yet protect it from the sun and wind. Fir trees 

 have been found much superior to pine as conservers of snow, and forests with 

 glades more satisfactory than continuous forests. Windbreaks on the lips of 

 canyons and on exposed slopes are indispensable for holding the snow." The 

 method of making estimates of stream flow based on the results of snow surveys 

 is described. 



Investigations on the relation of topography to tlie occurrence of frost in 

 continuation of those previously reported (E. S. R., 27, p. 240) furnished data 

 which " confirm earlier conclusions that, with elevation above the valley floor, 

 there is a decrease both in the number of frosts and in the number of hours of 

 orchard heating required, the decrease in the number of frosts with increase in 

 elevation of 250 ft. in the Truckee Meadows having been found to be from 14 

 to 5 and in duration of freezing temperatures from at least 40 hours to 16. 

 Also, except in abnormal years or in the coldest places, an average of two 

 heatings each season will save the fruit. Moreover, it seems probable that at 

 28° F. or higher, except when the fruit is setting, no heating will be necessary 

 to assure a moderate crop. ... A simple rule has been devised for forecast- 

 ing the probable maximum intensity of frost, namely, to subtract from the 

 maximum temperature of the day on which the forecast is made the fall in 

 temperature that normally occurs during the night when the weather is clear. 

 Id the spring at Reno this fall in temperature is 30 to 32°. Therefore, with a 

 maximum temperature of 65° the minimum temperature should not be lower 

 than 33°." 



The studies on the effect of site and blossom development and frost injury are 

 abstracted on page 40. 



A method of forecasting the maximum summer level in Lake Tahoe from 

 one to fo\ir months in advance, H. F. Alciatore (U. S. Mo. Weather Rev., 44 

 (1916), No. 7, pp. 407-409). — A proposed method which has been tested for two 

 successive seasons with satisfactory results xs based upon the inches of snow 

 (melted) falling monthly from December to April at nine stations in the 

 Truckee-Tahoe watershed (519 square miles). Tables are given showing the 

 average cumulative snowfall of these months at the nine stations during six 

 seasons and the average cumulative changes in the level of the lake from Decem- 

 ber to July, 1910-1915. The average change in level is found to be proportional 

 within certain limits to the average snowfall. Knowing the variation of the 

 actual snowfall from the average, it is easy to calculate the probable change 

 In lake level. 



" The results obtained in 1915, a season of light snowfall, and those for 1916, 

 a season of heavy snowfall, indicate that the proposed method is practical, 

 and that the estimates based on snowfall records for four stations are of 

 practically the same degree of accuracy as those based on a larger number of 

 records." 



The persistence of wet and dry weather, E. V. Newnham (Quart. Jour. Roy. 

 Met. Soc. [London], 42 (1916), No. 179, pp. 15S-162, figs. S; abs. in U. S. Mo. 

 Weather Rev., 44 (1916), No. 7, p. 593). — Analyzing the rainfall records of sev- 

 eral British stations by modern statistical methods, the author reaches the 

 conclusion " that during a long spell of wet weather there are no grounds for 



