278 



ENVIRONMENTAL CONDITIONS. 



Table 14. — Beginning, ending, and duration of each normally dry period and of longest 

 normally rainy period within the period of the average frostless season. (Plates 50 

 and 51.) — Continued. 



The lengths of the longest normally rainy periods in the period of 

 the average frostless season, as given in the third colu^mn of table 14, 

 are shown graphically on the chart of plate 50, in which the isoclima,tic 

 lines represent increments of 25 days. The total range for the country 

 is from nil to 256 (Cape Hatteras, North Carolina) . All of the region 

 west of about the one-hundred-and-first meridian has exceedingly low 

 values, most of them being zero, excepting the strip of country border- 



