FISHERIES, GAME AND FORESTS. 



419 



Risler's Experiments on the Yield of Water from Underdrained Areas. 









1867 



1868 



MONTH 



RAINFALL IN 



RUN-OFF BY 



EVAPORA- 



RAINFALL IN 



RUN-OFF BY 



EVAPORA- 





INCHES 



THE DRAINS 



TION 



INCHES 



THE DRAINS 



TION 



January, 



5-413 



4.O48 



1-365 



2.39I 



O 896 



1.494 



February, 







2.486 



I.679 



O.807 



o-374 



Q-337 



O.O37 



March, 







8.I39 



3.716 



4-423 



3- 6 97 



1.920 



I.776 



April, . 







6.I72 



2.804 



3-3 6 7 



2.598 



0.159 



2-439 



May, . 







3-972 



O.7O9 



3- 26 3 



1.649 



0.045 



I.604 



June, . 







3-179 



0.028 



3-!5i 



1.862 



0.000 



1.862 



July, • 







I.238 



O.OOO 



1.238 



4.704 



0.000 



4-7°5 



August, 







I.958 



O.OOO 



1.958 



2.906 



0.000 



2.906 



September, 







3-9°4 



O.OOO 



3-9°3 



6.216 



0.081 



6-135 



October, 







3- 6 93 



O.I3O 



3-5 6 2 



4.194 



0.958 



3-236 



November, 







0.293 



O.OOO 



0.293 



1.978 



0.784 



1.229 



December, 







i-545 



O.OOO 



J-545 



8.051 



5-7 2 7 



2.324 



Total foi 



year 





41.992 



13.114 



28.875 



40.620 



10.907 



29.747 



As shown by the table, the evaporation loss in 1867 was 28.87 inches, and in l< 

 29.75 inches. These figures are especially interesting as representing the total 

 evaporation loss from a catchment basin with an annual rainfall of from forty to forty- 

 two inches. They may be instructively compared with the evaporation data of 

 Genesee River given further on. 



COMBINED EVAPORATION OF SOIL AND GROWING PLANTS. 



The foregoing extracts from Risler's paper, Sur V Evaporation du Sol, and the 

 accompanying table, serve to illustrate the combined evaporative effect of the soil and 

 growing plants. By way of illustrating why plants contribute powerfully to increase 

 evaporation, we may refer to the following data from Durand-Claye giving the 

 relation between the evaporating surface of a number c f agricultural crops and the 

 unit area of the soil on which they grow: 



Potatoes, 



. 6.88 



Wheat, . 



• 10.95 



Lucerne, 



7.02 to 12.40 



Grass, 



12.40 



Rye 



6.50 to 8.24 



Clover, . 



. 16.36 



Indian corn, 



8.00 to 22.40 



Grape vines, . 



4.94 



Branching cabbage, 



. 8.00 



Oak trees, 



9.00 



Oats, .... 



. 9.11 



Fir trees, 



• n-75 



