FORESTS AND FRUIT-GROWING. xg7 



boring streams receive a continual supply, while its evaporation from 

 the surface and its transpiration through the leaves of the trees afford 

 moisture to the atmosphere. 



The moisture thus imparted to the atmosphere mitigates the sever- 

 ity of a drought in various ways: First, by lessening evaporation 

 from the surface, as this is accelerated by a dry atmosphere, and re- 

 tarded by a moist one ; secondly, by affording to the soil a greater pro- 

 portion of moisture for condensation, when the surface cools at night. 

 Thirdly, by affording moisture for direct absorption by the leaves. 

 This is a disputed point among men of science ; but the late researches 

 of Cailletet promise a reconciliation of the conflicting views, as usual, 

 by showing that both were wrong and both right. He found that, 

 when a plant was abundantly supplied with moisture in the soil, the 

 leaves never absorb ; but that they do absorb whenever the soil is de- 

 ficient in moisture, and the leaves begin to droop. 



Hence, there might be evidence of drought in a country without 

 forests, while there were no such evidences in a country sufficiently 

 guarded by forests, though the amount of rain had been the same in 

 both. 



These considerations are not altogether without value in regard to 

 fruit-growing. It is true that grapes do best in rather a dry climate ; 

 but most kinds of fruit require considerable moisture, especially at 

 the time of transplanting, and also when the fruit is maturing. In af- 

 fording some mitigation of the extreme effects of dry weather, forests 

 may be regarded as having a beneficial influence on the growing of 

 most fruits. 



Of far greater concern to the fruit-interests of any locality is the 

 influence of woodland on temperature. On this subject there is quite 

 a general unanimity of opinion. Certain forms of the evidence are so 

 familiar that the conviction produced is general. Every one, who has 

 travelled through woodlands and open fields during cold weather, has 

 readily perceived how much warmer was the atmosphere of the wood 

 than that of the field. It is said that engineers on our railroads find 

 that it requires less fuel to keep up steam in passing through a long 

 stretch of woodland (Marsh). But the warming influence of the 

 forest has been subjected to more rigid tests than these. Boussin- 

 gault proved that, within several parallels of the equator on either 

 side, the temperature of cleared land is about two degrees higher than 

 that which is covered with forest. But we are more directly con- 

 cerned with results in our temperate climate. 



The researches of Becquerel, Krutsch, and Berger, had appeared to 

 prove, first, that a wooded region would have a cooler summer and a 

 warmer winter than a region almost destitute of woods ; and, secondly, 

 that during the daytime the temperature of the atmosphere in the for- 

 est would always be lower, and during the night always higher, than 

 in the open field ; the difference between the diurnal maximum and 



