74 ANNALS NEW YORK ACADEMY OP SCIENCES 



lished in the Monthly Weather JJeview of 1884 and 1885, and I'or the 

 sake of comparison I give his conclusions below.^° The results I have 

 obtained so far are so different from those of Helm Clayton that it is 

 perhaps necessai^ to insist once more upon the fact that my maps are 

 annual (l('])ai'tiirc nuips, whereas the maps utilized by him were monthly 

 departure maps. Even in the case of monthly maps of temperature, 

 however, Clayton's generalizations must be considered as sim])ly plausible 

 hypotheses, which may disagree with the observed facts. The departure 

 maps for the months from August to November, 1912 (see Monthly 

 Weather Eeview), will serve as an example. 



'I'he method of research 1 have adopted is evidently the same as that 

 of Clayton'^ and the pleionian variation, of equatorial regions in par- 

 ticular, is certainly the same phenomenon as the meteorological cycle 

 of twenty-five months' duration discovered by Clayton,-^ or the longer 

 cycle, of about three years, advocated by Lockyer and others. 



Though the method of using consecutive means, and tracing departure 

 maps, has already been used long ago, it has not yet been applied to the 

 scientific study of climatic variations in a suflficiently extensive and 

 careful way to lead to the results of general interest and practical ap- 

 plication which we might expect to obtain. 



Before entering into the details of the description of the departure 

 maps of the years 1900 to 1909, I will take into consideration the geo- 

 graphical j-epartition of the range of variation of the annual means of 

 temperature. 



On Bigelow's tables-^ T have formed the differences between the high- 



"""1. There are areas of baromodic depression, and clovatioii, whli'li occupy weeks 

 and months In their movements across the continent from West to East. 



"2. There exist, independent of the movements of areas of barometric depression, and 

 eievatlon, nniiieroiis seesaw oscillations in the pressure whicli liavc bw^n given tlie name 

 of surpes. 



"3. In front of and to the south of areas of barometric dejiression of slow movement 

 and long duration, as in those of rapid movement and short duration, the temperature 

 is above the normal : and below the normal north of them and in their rear which is 

 usually the fr(mt of barometric elevations. In front of, and to the sontli of. areas of 

 barometric elevation of lotifr [icriod. as in those of short period, the temperature is below 

 the normal, and above north of them and in their rear which is usually the front of 

 depressions. (In winter the area of warmth approaches and usually includes the area 

 of lowest pressure, and the area of cold aiiiiroacbes jind usually includes the area of 

 highest pressure; in summer, vice versa.) 



"4. In front of, and within, baroineti'ic deiu-essions of long period, as In those of 

 short, the rainfall is above the normal, and below, in their rear. In front of, and 

 within, barometric elevations of long period, as in those of short, the general tendency 

 is towards fair and clear weather with deficient rainfall.'" 



^ IlEN'itv IIkl.m rr.AVTON : "A projiosed new method of weather forecasting by analysis 

 of atmospheric conditions Into waves of different lengths." Monthly Weather Ueview, 

 1007. p. 161. See also : 



IIe\ry Gawthrop : Temperature curves (lliid., ji. .")7C), 



=2 American Meteorological .Tournal, Vol. 1. p. 1 ."^0. 1SS4. 



" Op. cit., Bull. S. 



