^ 52 — 



Isophanal Map of the United States in =; degree isophanes and 1x5 degree quadrangles to illus- 

 trate method of designating phenological areas for the study of influences which contribute to 

 time, attitude or latitude depurturcs from the geographical constants. The estimated minus (earlier) 

 and plus (later) departures in days from the computed time constant for spring and autumn events 

 as given for each quadrangle, are based on a study of more than 40,000 reports on the date wheat 

 harvest begins and on other statistics of planting and harvest dates for wheat, potatoes, etc., and 

 represent averages for the entire quadrangle. 



Aa Isophanal May of New York State with a chart for the determination of the best date 



for sowing fall wheat. 



