EVAPORATION IO9 



as it afterwards developed, the water used in this standard- 

 ization was impure, so that the standard cup gradually 

 became clogged, and the coefficients then obtained were in 

 many cases incorrect. At the end of the season, however, 

 the cups were returned to the Desert Laboratory, and there 

 restandardized. I he new correction coefficients thus ob- 

 tained are the ones used for the results here to be given, 

 with the exception of a few instruments which were received 

 in bad order or not returned at all. For these instruments 

 the old coefficients have been used. 



The results obtained from the season's records are only 

 partially satisfactory, for several reasons besides the trouble 

 with the standardization, already mentioned. Some of the 

 observations were not continued throughout the entire 

 period; gaps occurred in some of the series, due to accidents; 

 several cups could not be restandardized, for one reason and 

 another, and the original selection of localities for the sta- 

 tions was found to be inadequate to represent the areas 

 occupied by the vegetational centers. Atmometers placed in 

 regions intermediate between those of vegetational centers 

 gave data as difficult to analyze as are the vegetational 

 characters of such regions. It is planned to continue this 

 inquiry through another growing season, with a larger series 

 of more carefully placed stations. 



Following is a table of the data from sixteen stations. 

 The data for the other stations in the original series are un- 

 trustworthy, on account of incompleteness or for other 

 reasons. In the table are represented four partial periods, 

 corresponding roughly to the months, June, July, August 

 and September. The first period comprises four weeks, the 

 second four, the third five, and the last four. In the first 

 column of the table are giv^en the name of the station and 

 that of the observer. The four following columns present 

 the averages of the weekly losses for the four monthly 

 periods, respectively. These rates are in cubic centimeters, 

 and are to be considered onlv as relative measures of the 



