AGRICULTURAL TEXT-BOOK. 49 



but that neither will thrive on the other sides, respectively, of that line, 

 nor will they if the species are crossed.&quot; The same peculiarities are 

 found in other parts of the world. The cause is not yet satisfactorily 

 ascertained, but is undoubtedly more or less dependent on climate. 



140. Through a perfectly dry argillo-calcareous soil, in a 

 state of fallow, rain descends in one day six times the depth of 

 the quantity fallen. Thus a fall of 4-10ths of an inch will sink 

 in a day through nearly 2j inches. (Gasparin*) 



141. The power of the soil to absorb and retain&quot; moisture, is 

 practically, an important consideration, and greatly influences 

 the effects of the annual quantity of rain falling. The amount, 

 of water which a cubic foot of various soils can contain before 

 they allow any of it to run off was determined by M. Schubler : 



A cubic foot of 



Siliceous sand held of water 27,3 Ibs. 



Calcareous sand &quot; SI. 8 &quot; 



Sandy clay &quot; 38.8 



Loamy clay &quot; 41.4 &quot; 



Stiff clay, or brick earth, &quot; 45.4 fa 



Arable soil &quot; 46.8 



Garden mould &quot; 48.4 



142. The relative degree of rapidity with which rain water 

 is evaporated, was also ascertained. Of 200 parts of each earth 

 exposed for four hours, on a thin surface in a closed room, at 

 65f Fahrenheit, there was an evaporation of absorbed water as 

 follows : 



Siliceous sand lost 88.4 parts in 100 parts of absorbed water. 

 Calcareous sand &quot; 75.9 &quot; &quot; &quot; 



Sand clay &quot; 52.0 &quot; &quot; &quot; &quot; 



Loamy clay 45.7 &quot; 



Stiff clay, 35.9 



Arable soil &quot; 32.0 &quot; 



Garden mould &quot; 24.3 &quot; 



It is readily perceived how different must be the effect of 

 dry weather upon crops grown in these various soils. 

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