510 EXPEEIMENT STATION RECORD. 



Climatic changes, E. Huntington {Gcoi/r. Join:, Ji4 {1914), No. 2, pp. 203- 

 210). — This article deals more pfirticularly with what are known as long-period 

 climatic pulsations and progressive dessication of the earth. The general con- 

 clusion is that it is not possible to say whether the earth as a whole is becom- 

 ing wetter or drier. Apparently there has been no general change of climate 

 within historic times. 



The meteorolog'ical conditions of an ice sheet and their bearing on the 

 desiccation of the globe, C. E. P. Brooks {Quart. Jour. Roy. Met. Soc. 

 ILondon], JfO {191^), No. 169, pp. 53-10). — The author cites evidence to show 

 that " a well-marked cold period in the north has been associated with Increased 

 rainfall over all the more southerly regions for which information is avail- 

 able. . . . 



" The regions occupied by extensive ice sheets at the present day, viz, Ant- 

 arctica and Greenland, are the centers of permanent high-pressure areas, with 

 slight precipitation. We therefore infer that the regions occupied by similar 

 ice sheets in the glacial period were likewise occupied by permanent anti- 

 cyclones. 



" The maximum extent of glaciation occurred at about the same time in 

 different regions of the globe, and also coincided with the maximum of the 

 pluvial iieriod. or period of greater rainfall than the present, in the unglaci- 

 ated regions. But a general decrease in temperature should lead to a decrease, 

 not an increase, in the amount of evaporation, and hence of precipitation. 



" The explanation of the paradox lies in the different distribution of the pre- 

 cipitation. Various causes tended to minimize or reverse the effect of the 

 fall of temperature in decreasing evaporation ; thus, while the total precipita- 

 tion over the globe may have been somewhat less than now, so little of it fell 

 over the ice sheets that the remainder, falling upon the unglaciated areas, ren- 

 dered these considerably moister than now. 



" Since the culmination of the ice age desiccation has progressed with the 

 retreat of the ice. Slight reversals have taken place ; an example is the period, 

 cold in the north, moist in the south, from the ninth to the thirteenth 

 centuries." 



Recent studies of snow in the United States, J. E. Church, Jr. {Quart. 

 Jour. Roy. Met. Soc. [London], 40 {191-',), No. 169, pp. 43-52, fig. i).— This is 

 an account of studies made by the Nevada Experiment Station on Mount Rose 

 and in the vicinity of Lake Tahoe (E. S. R., 28, j). 514 ; 29, p. 814). It describes 

 the snow sampler and weigher used and discusses especially data secured on the 

 relation of mountains and forests to conservation of snow. 



It was found that the forested slope of Mount Rose contained " an average 

 water content one-fifth greater than the unforested but protected slope above 

 it, nearly twice as much water as the cornice at the apex of the mountain, over 

 fourteen times the moisture conserved by the wind-swept slope, and more than 

 twice the average water content of all three are-is combined. . . . 



"Area for area on mountains of gentler contour (and such mountains are the 

 rule rather than the exception) the talus slopes are less efficient than forests 

 as conservers of snow% ... It is true that some of the snow above timber-line 

 outlasts the snow in the forest below. This phenomenon is confined, however, to 

 the deeper cornices of limited area. The use of timber screens instead of a 

 forest cover evenly distributed would create drifts but little inferior in size and 

 lasting power to the cornices on the talus slopes. Furthermore, the number 

 of such drifts can be multiplied by planting trees, while the cornices on the 

 rocks not only can not be increased in number, but also place too large an area 

 under contribution if compared with the moisture conserved. Their only virtue 

 is that the water they do furnish is released late." 



