246 



Thus, again, Risler, at Caleves, in France, measured the harvest 

 and the rainfall in an open field, having an impermeable subsoil. 

 He measured the quantity of rainfall and the outflow through the 

 drains, and allowed for the moisture in the soil at the beginning and 

 end of his experiments. The result attained was that a field of winter 

 wheat consumed 256 millimeters in depth of water from April to July. 

 He does not give the quantity of grain that was harvested. 



Marie-Davy, at Montsouris, cultivated winter wheat in twelve sam- 

 ples of earth of very different qualities, in 1874. The soil was 

 enriched with compost, with results as in the first part of the follow- 

 ing table. 



In 1875 the soil was enriched with Joulie's complete fertilizer for 

 cereals at the rate of 1,000 kilogi^ams per hectare, with results as in 

 the second part of the table. 



Evaimration and crops at Montsouris. 



We remark that in these two years the quantity of water evaporated 

 has remained the same, but the harvest changed notably, being in 

 both cases much superior to those of Rothamsted and Caleves. A 

 box of earth, similar to those containing the wheat, lost by evapora- 

 tion from January 2G to June 9, 1875, 114 millimeters, while a box 

 planted with wheat lost 35G millimeters, and the Piche evaporimeter 

 lost 302 millimeters. Similarly, in 1876, from the 22d of February 

 to the 5th of July, the soil covered with winter wheat lost 426 milli- 

 meters, but the naked soil 163 millimeters and the I^iche 465 milli- 

 meters. However, in this connection it must be noted that while the 

 boxes containing naked soil received only the natural rainfall, those 

 containing the growing plants received weekly the water that they 



