,02 GENERALIZATION OF THE PRECEDING TABULAR RESULTS 



a northeasterly direction to the winds of Florida, to those of southern Lousiana, and 

 to those of southeastern Texas ; this is the season of the so-called " northerners." 

 Under these conditions the diffusion of the moisture of the Gulf is, in a measure, 

 counteracted, the ascending current of vapor is feeble and soon descends and mingles 

 with the western current, to be driven to the Atlantic coast, along which, north of 

 South Carolina, there is a slight increase of rain-fall. The remarkable rain area 

 wliich had its centre in Iowa during the summer entirely disappears, indeed, in this 

 region northwest winds have taken the place of southerly summer Avinds, and we 

 have now but 4 inches of rain. In southern California the west winds prevail, they 

 reach across Arizona and New Mexico, as northerly and westerly currents, and are 

 deflected into northerly winds in southern Texas. The heavy rains on the coast of 

 Oregon and Washington Territory take place under the influence of southwesterly 

 and southerly winds, the latter prevailing in Washington Territory. On this coast 

 more than double the amount of rain falls than the maximum in Louisiana, though 

 its temperature is as low as 40° or at most 48° Fahrenheit, that of L(juisiana being 

 about 52° Fahrenheit. In ;ill that region lying north of western Texas, pai-t of 

 Kansas, Nebraska, and Dakota, and again north of the head of the Grulf of Cali- 

 fornia, and extending to southern Nevada, less than 2 inches of rain fall during the 

 winter season. 



CHART SHOWING THE DISTRIBUTION OF THE RAIN-FALL DURING THE SPRING. 



It exhibits the iso-hyetal curves for every third inch from 3 to 18 inches, and 

 beautifully illustrates the spread of the vapor northward and Avestward from the Gulf 

 coast to the great lakes, Avith a branch merging into tlie eastern atmospheric drift 

 and reaching the coast at Cape Hatteras, this branch extending to Massachusetts and 

 producing coast rains. The greatest rain-fall in the east, in Louisiana, of 18 inches, 

 is just e(pialed by the greatest rain-fall in the Avest in Washington Territory. The 

 18 inches of rain in Louisiana, Ai-kansas, and Mississippi are reduced to one-half 

 that amount near the southern shore of Lake Superior ; in the Avest the maximum 

 rain-fall is reduced to one-third of the amount just east of the Cascade Range and of 

 the Sierra Nevada. The distribution of rain in the spring has features in common 

 Avith the Avinter and the summer i)recipitation ; it exhibits still the remains of the 

 ^\ inter rains on the northwest coast, and preserves the scanty supply of water over 

 Florida ; Avhile, on the other hand, it points out very characteristically the high roads 

 over which the moisture is carried and deposited from the Gulf to the lakes and to 

 the middle Atlantic coast. 



