METEOROLOGY WATER. 313 



plete treatise, of which tliis is part 1, will be in four parts. The reviewer in 

 Nature considers this first volume very complete and up-to-date. He states 

 that " in no other treatise are the questions relating to underground tempera- 

 ture expoimded in so complete a manner. The discussion of the results of the 

 author's observations on the temperature at different depths in soil covered 

 with grass and otherwise is especially noteworthy." 



The titles of the chapters in this volume are as follows : Composition of the 

 atmosphere, physical properties, water in the atmosphere, the oceans, solar 

 radiation, terrestrial radiation, earth temperature, increase of heat with depth, 

 ocean temperatures, tempei-ature of the lower strata of the atmosphere, at- 

 mospheric pressure, formation of hydrometeors, temperature and pressure in 

 the upper atmosphere, [and] abnormal departures. 



The correlation of climatic variations, H. Arctowski { L' E nchainement dcs 

 Variations Cliinatitjiics. Briis.'^eJs, J'JOO, pp. 13'), Jigs. 6.2 ; rev. in Science, n. ser., 

 31 (1010), Xo. 78'/, pp. 25, 26). — ^This is a memoir based on a review of mean 

 annual temperatures, 189] to 1900, for the northern hemisphere. The varia- 

 tions are illustrated by means of charts for each year showing the geographical 

 distribution of annual departures from normal temperatures (10 years). On 

 these maps areas of positive departures are called thermoi)leions or simply 

 pleions and negative areas antipleions. The pleions and antii)lelons are bounded 

 by what is designated the quasinormal line, while lines of equal positive and 

 negative departures are termed hypertherms and hypotherms. 



In a review of this memoir in Science the author states: 



" The pleions represent inflections of the isothermal lines toward the pole, or, 

 more properly speaking, toward the regions of colder climate. 



" The antipleions, on the contrary, characterize a local abnormal descent of 

 the isotherms toward the equator. 



" The maps of successive years, for the same country, ahd those of different 

 countries for the same year, show remarkable correlations in the distribution 

 of the departures. 



"A pleion, in most cases, exists during several years, moving from place to 

 place. When one compares the different maps, and especially those of Euro- 

 pean and Asiatic Russia, one is led to believe that the pleions are produced by 

 immense waves intercrossing. It seems that for the whole world the years are 

 either too wai*m or too cold following the predominance of pleions or anti- 

 pleions. For example, the year 1893 was exceptionally cold, 1900 on the con- 

 trary was too warm. The temperature of the earths atmosphere was at least 

 one-half a. degree Centigrade higher during the year 1900 than during 189.3. It 

 is a notable fact that neither the Alps, the Caucasus, nor the Rocky Mountains 

 form barriers, not even the Himalayas interrupt the progress of a pleion or an 

 antipleiou. This demonstrates the fact that the thermopleions and antipleions 

 are products of temporary alterations of the general circulation of our atmos- 

 phere." 



The utilization of these correlations as a basis for weather prediction and for 

 developing methods for further investigation is briefly discussed. 



Extreme winters and summers (Rev. Sci. [Paris], Jfl (1909), II, No. 16, 

 pp. 500, 501). — An attempt is made to show a certain periodicity in the occur- 

 rence of extreme winter and summer temperatures and to trace a relationship 

 between such seasons and certain solar activities. 



On Lockyer's 35-year period in the solar activity, C. Easton (K. Akad. 

 Wetensclt. Amsterdam, Proc. Sect. Sci., 11 (1908-9), pt. 2, pp. 8/,2-S-!t7, pi. 1).— 

 Evidence is adduced to show " that Lockyer's opinion, according to which a 

 35-year period should be traceable in the materials now at hand, is untenable," 



