1g1t] - FULLER—EVAPORATION AND SUCCESSION 195 
correcting valve. It is the intention of the writer, however, to 
employ this improved atmometer, also devised by LivincsTon (*7), 
in the continuation of these studies. 
Fifteen different stations were established in the various asso- 
ciations, care being taken to select spots which possessed the average 
amount of tree, shrub, and herbaceous vegetation characteristic 
of that specific association as a whole. Owing to a variety of 
accidents and other circumstances, all the stations did not give 
equally satisfactory and continuous records; hence the present 
preliminary report is confined almost entirely to the results from 
Io stations in 4 different associations. Many of these records 
extend from May 6 to October 31, or over a period of 178 days; 
at other stations the record begins at a somewhat later date, but 
continues until the severe frosts of November 1, and includes the 
important part of the growing season for all except a few very early 
spring plants. 
In order to facilitate comparisons between the various stations, 
and to exhibit the progress of the evaporation rate during the entire 
season, the average water-loss per day between the weekly readings 
has been calculated, and the results expressed in graphs with 
ordinates representing the number of cubic centimeters lost per 
day by a standard atmometer, the abscissae being the intervals 
between the weekly readings. The readings included within each 
calendar month are indicated at the top of the diagram. For con- 
venience of reference, the stations are numbered consecutively, 
beginning with that nearest the lake shore. 
The first group of stations was upon some slowly moving dunes 
directly north of the village of Millers, Ind., and between the 
southern shore of Lake Michigan and the Grand Calumet River. 
According to old maps, this river formerly discharged its waters 
into Lake Michigan very near the spot selected for one of these 
stations. Any such discharge has long since ceased, and its exact 
location has been entirely obscured by the advancing dunes, leaving 
the remaining river bed as a shallow channel in which the water has 
little or no current, the present discharge being some eight miles 
farther west. Dunes are now advancing into this channel at several 
points, and within a few years will doubtless occupy other portions 
