270 



The Plant World. 



although the amount of precipitation was not excessive for the 

 tropics; the operations were necessarily discontinued before the 

 summer rainy season was well advanced. At the end of the first 

 two weeks all cups were replaced by new ones and at the end of 

 the entire period all were recalibrated at the Desert Laboratory. 

 No changes in the coefficients of correction were n:anifest at the 

 final calibration, so that the readings have been corrected by 

 means of the original coefficients. The corrected increments of 

 water loss for each of the four instrum.ents, are presented in the 

 table, which also includes the derived evaporation rates in 

 centimeters and inches of depth from a ten-inch tank. (For 

 the non-rain-absorbing instruments, for the method used, see 

 Livingston, 1910, p. 11^). The rainfall for the diff'erent partial 

 periods and for the two stations is also given, as well as all totals 

 for the whole period of 25 days. 



STATION IN OPEN. 



STATION IN RAVINE. 



i Ordi- 



n.iry 



Atnio 



i meter 



Vol. 



cc. 



. 71 2.9 



6.5 



3.4 



0.5 



11.1 



0.0 



0.0 



1 .4 



4.3 



Non -rain -Absorb ina 

 Atmomcter. 



Vol. 

 cc. 



5.5 



4.1 



5.8 



Depth 



0.78 



0.58 



o.o: 



0.02 



0.82 0.03 



3.8 0.54 0.02 



19.21 2.72 0.11 



0.8 



4.4 



6.6 



0.2 



12.0 



It will be observed from the table that the evaporation rate 

 in the shaded ravine was exceedingly low. The highest of the 

 weekly rates was 5.8 cc, though the calculated weekly rate cor- 



