TRANSPIRATION OF SILPHIUM 



313 



there was but slight difference in temperature at the three different 

 heights. 



In the graphs for this experiment (fig. 1, fig. 2) the curves 

 are nmnbered in order from the lowest position to the highest. 

 In the first graph the solid lines represent evaporation, and the 

 broken lines represent wind velocity. 



P^om these data it appears that evaporation increases more 

 or less regularly with an increase in height, for moderate heights 



TABLE 3 



Evaporation (in rvb-ic inchea) from Piche evaporimeters at different heights {in 



centimeters). 



DATE 

 1912 



July 11 



July 13 



July 16 



July 18. . .■. . 



July 23 



July 25 



July 29 



August 6. . . . 

 August 19. . . 

 August 20 . . . 

 August 21. . . 

 August 22.. . 

 August 25. . , 

 August 26 . . . 

 September 1 

 September 2 

 September 5 

 September 7 



NO. I 



Height 



6.0 

 5.5 



4.0 

 9.0 

 9.0 

 10.0 

 10.0 

 7.0 

 5.0 

 6.0 

 6.0 

 6.0 

 16.0 

 6.0 

 6.0 

 6.0 

 6.7 

 6.7 



Loss 



0.240 

 0.240 

 0.220 

 0.165 

 0.365 

 0.145 

 0.130 

 0.170 

 0.200 

 0.210 

 0.195 

 0.190 

 0.340 

 0.165 

 0.305 

 0.275 

 0.450 

 0.290 



NO. II 



Height 



26.5 

 20.5 

 37.0 

 15.5 

 25.0 

 26.0 

 26.0 

 29.0 

 22.0 

 25.0 

 25.0 

 25.0 

 25.0 

 25.0 

 25.0 

 25.0 

 30.0 

 30.0 



Loss 



0.280 

 360 

 0.375 

 0.180 

 0.605 

 0.230 

 0.220 

 0.245 

 0.240 

 0.260 

 0.260 

 0.240 

 0.390 

 190 

 0.360 

 0.300 

 0.600 

 0.330 



at least. Taking the lowest evaporimeter as the standard or 

 100%, the loss of the next evaporimeter was 130.3%, and that 

 of the highest evaporimeter was 170.7%. Since there was not 

 much difference in temperature at the different heights, the 

 increase in the rate of evaporation with an increase in height 

 must have been due to an increase in wind velocity more than 

 to any other one cause. 

 As it might be claimed that one experiment is not conclusive. 



