METEOROLOGY — WATER. 7 17 



to meteorological conditions, especially with reference to the critical periods of 

 growth, the author gives calculations for Sicily of the frequency of 10-day 

 periods of rainfall between 0.1 and 5 mm. and of 10-day periods without rain, 

 and discusses the bearing of these data upon rain distribution and plant growth 

 in Sicily. He is of the opinion that in a region like Sicily, which has distinct 

 rainy and dry seasons, it is more important to know the occurrence of the rainy 

 periods than the dry periods. 



"An examination of the 10-day periods with a total rainfall of 5 mm. (0.2 in.) 

 shows that different values must be attached to them, according to the time of 

 the year at which they occur ; that is to say, during periods of regular rainfall 

 a 10-day period with a total of 5 mm. is really a dry period comparable to one 

 having no iniluence on vegetation, while, on the other hand, if it occurred in a 

 period of extreme dryness, e. g., during the summer months in Sicily, such a 

 period could exercise considerable influence. It would appear, therefore, that 

 the rainfall measurements would be more profitable if the probability of the 

 period with low rainfall greater than 5 mm. were known, and also those of abso- 

 lute drought." 



Is the earth drying up? {Quart. Jour. Roy. Met. Soc. [London'], 40 (1914), 

 No. no, pp. 165, 166). — This Is a brief discussion of a paper by J. W. Gregory 

 already noted (E. S. R., 30, p. 815). emphasizing especially the conflicting evi- 

 dence and views upon this subject. 



A study of the changes in the distribution of temperature in Europe and 

 North America during the years 1900 to 1909, H. Akctowski (Ami. N. Y. 

 Acad. Sci., 24 {1914), PP- 39-113, figs. 61). — Following the procedure adopted in 

 a previous paper dealing with temperature data for 1891 to 1900 (E. S. R., 23, 

 p. 712) and considering the means for that decade as quasi-normal values, the 

 author calculates for each year from 1900 to 1909 and for each station the depar- 

 tures from these means. Curves are presented showing these annual departures, 

 the positive departures being designated thermopleions, the negative departures 

 antipleions. 



These curves show that the year 19(X) was one of predominant thermopleions 

 while in 1893 the antipleions strongly predominated. It is estimated that the 

 difference in temperature between these two years must have been at least 

 0.5° C. 



For the purpose of making the necessary comparisons the temperature curve 

 of the exceptionally undisturbed climate of Arequipa, Peru, for the years 1900 

 to 1910 was taken as the standard. This curve shows four characteristic crests 

 and four depressions for the period named. 



The paper presents data to show " that in far distant regions of the globe, 

 simultaneously with the appearance of the Arequipa crests pleions are formed; 

 that these pleions have a tendency to persist ; that, in order to persist, one 

 must displace another. Pleions and antipleions are correlated; if one moves, 

 the other moves. In North America the displacements seem to be confined to 

 the North American Continent. In consequence, the pleions must pendulate 

 from one side to the other. Moreover, the differences between the pleionian 

 crests and the antipleionian depressions of temperature change. These changes 

 of amplitude seem to be in immediate correlation with the equatorial changes 

 of temperature. . . . 



" The existence of macropleioniau variations, the close correlation of the 

 pleionian phenomenon with the Arequipa variation, the compensating anti- 

 pleions, and, finally, the djoiamic character of these climatic changes, eliminate 

 . . . the hypothesis attributing such changes exclusively to the presence of 

 variable quantities of volcanic dust in the higher layers of our atmosphere. 



