1913] NICHOLS—SUMMER EVAPORATION INTENSITY 149 
columns of figures in table I reveals the fact that during the first 
two monthly periods the mean weekly rate of evaporation far 
exceeded that maintained during the latter part of the season. In 
other words, the period of maximum evaporation coincided approxi- 
mately with the more critical period of vegetative activity. In view 
of this correlation, coupled with the natural assumption that it is 
the periods of excessive evaporation that are most influential in 
determining the character of vegetation, it has been thought best 
in drawing conclusions to disregard entirely the data obtained 
during the latter part of the season, when for the most part a uni- 
formly low rate of evaporation prevailed throughout the state, 
and to base deductions on the observations of these first two months. 
The mean weekly rates of evaporation obtaining at the various 
stations from June 1 to August 3 have therefore been indicated in 
the last column of table I. With these figures as a basis, it is a 
simple matter to compute approximately the relative evaporating 
power of the air for the various geographical and vegetational 
regions of the state during the period of combined maximum vege- 
tative activity and evaporation intensity for the year 1912. Upon 
averaging the results for the inland stations of the Highlands and 
Lowland and of the stations along the coast, it is found that the 
weekly water loss, as recorded by the porous cup atmometer, was 
as follows: Western Highland, 137 cc.; Central Lowland, 171 cc.; 
Eastern Highland, 173 cc.; Coastal Region, 135 cc. It would 
thus appear that the area dominated largely by the mesophytic 
northern hardwood type of forest, and the strip along the coast, 
constitute areas of relatively low evaporation intensity; and that 
the rate of evaporation in the Eastern Highland, where oaks pre- 
dominate in the forest, is somewhat higher than that in the Central 
Lowland, where the more mesophytic chestnut is the character 
tree. The relatively low evaporation rate along the coast was not 
wholly unexpected and will be referred to again. Explanation 
for the gradual diminution in evaporation intensity apparent in 
passing from west to east along the coast may be looked for in the 
fact that while the western part of the shore is shut off from the 
ocean by Long Island, the eastern portion is more exposed and 
therefore possesses a more maritime climate. 
