CLIMATIC CONDITIONS OF THE UNITED STATES. 321 



east (in the Gulf of Mexico) and reenters the continent sufficiently 

 to demark the Gulf coasts of Florida and also a Uttle of the Atlantic 

 coast near Jacksonville, as pertaining to the zone of medium evapora- 

 tion intensities. Thus the northern area of low intensities is broadened 

 southeastward from New England, to include nearly all of the Atlantic 

 and Gulf coast region, which suggests no very great alteration from 

 the condition of affairs depicted by the 1908 chart. This way of regard- 

 ing the zonation thus considers that the Minnesota-Kansas lobe of 

 the northern zone of low intensities is represented only on the 1908 

 chart, that the northern zone is otherwise much widened southward 

 throughout its eastern half on the 1908 chart, and that the Maine- 

 Mississippi lobe of this same zone is represented on both charts, being, 

 however, more extensive on that for 1888. 



(3) One of the main differences between the two charts hes in the 

 portion of the great eastern lobe of the zone of medium evaporation 

 intensities. While this lobe extends northeastward from Oklahoma 

 and Texas in the 1908 chart, it extends eastward from Nebraska in the 

 1888 chart. In the latter it does not attain as great a northerly exten- 

 sion as in the former, and it practically reaches farther east in the 

 region of Chesapeake Bay (on account of the localized area of that 

 region) in the 1888 chart. As has been noted above, the zone of inter- 

 mediate atmospheric evaporating power occupies practically all of the 

 Gulf coast and all of the Atlantic coast as far north as New Jersey, 

 on the 1908 chart, but this zone is, as it were, nearly crowded off from 

 the continent on the 1888 chart. 



From the above considerations it appears that the two charts are 

 not in nearly so great disagreement as a first view might suggest. They 

 agree very well in depicting the desert region. They agree in showing 

 a southward extension of the northern zone of low evaporation, on 

 each ocean border, and in showing the eastern of these extensions as 

 embracing the Appalachian Mountains south of Pennsylvania. They 

 agree in depicting a zone of intermediate evaporating power, including, 

 roughly, the western half of the country (excepting the most arid part), 

 the region of the main great mountain-mass, and the high plains east 

 of this. Finally, they agree in showing that a great lobe of this inter- 

 mediate zone extends eastward or northeastward from the main area, 

 and that this lobe embraces the region immediately west of the Appala- 

 chian Mountains. 



Whether all these generalizations from imperfect observations, for 

 two periods 20 years apart, may prove generally true throughout a 

 long period of years will hardly be known by the present generation — 

 nor even by the next following one, unless atmometry begins to 

 attract serious attention in the very near future. They are of little 

 value at present, excepting as very rough approximations and as they 

 indicate how important among climatic features is the evaporating 



