1-8 THE POPULAR SCIEXCE MONTHLY. 



be given out again to a drier atmosphere and to surrounding objects- 

 It is well known, also, that the leaves of the trees, as they fall from 

 year to year and decay, form a spongy soil, which absorbs the rains 

 that fall upon it, and retains them, when otherwise, where there is any 

 declivity, the water would run off almost immediately. The roots of 

 the trees, likewise, penetrating deeply into the ground, conduct a con- 

 siderable portion of the moisture falling from the clouds far below the 

 spongy surface-soil.* Shaded by the leaves and branches of the trees, 

 the moisture thus stored up is not soon evaporated, as it would be 

 from the open ground, but passes off slowly into the surrounding air, 

 and imparts its benefits in the largest measure to the adjacent lands. 



While thus sending out their moisture upon the cultivated fields 

 around them, and thereby favoring the growing crops, the forests aid 

 the work of husbandry in another way. By their very mass they 

 serve as a mechanical barrier against the winds, which are often so 

 injurious to crops. Every one who has visited the forest with any 

 frequency knows that he is obliged to go but a short distance within 

 its borders to escape the influence of even a violent wind. So it is 

 also well known that the woodmen engaged in felling trees in the 

 forest, which they usually do in the winter, find no inconvenience 

 from cold winds, as these penetrate the wood but a short distance, 

 even when the trees are stripped of their leaves. And as the woods 

 shelter those within them from the winds, so do they protect the 

 adjacent fields from the blasts which would otherwise sweep over 

 them, and, by their cold, their mechanical force, and their desiccating 

 influence, prove very injurious to crops. The presence of a forest is 

 often, on this account, in its effect upon adjacent lands, equivalent to 

 a change of latitude of several degrees. This is sufiicient to make 

 the cultivation of certain crops successful which otherwise could 

 not be undertaken. There are districts of France and Italy where 

 the olive and the orange once flourished, but where now, on account 

 of the change of climate resulting from the extensive removal of the 

 forests which formerly abounded, they can no longer be grown with 

 success. It is not going too far to say that, if one fourth of the land 

 now under cultivation were converted into forests and groves so dis- 

 posed as to form barriers against the coldest and strongest or most 

 prevalent winds, the remaining three fourths would have more value 

 for agricultural purposes than the whole has at present. This would 

 result from the greater variety of crops which could be raised, their 

 earlier maturity, the greater certainty of growth, and the larger ag- 

 gregate yield, while there would be, in addition, the large product of 

 the forest itself, to be used, as occasion might demand, for fuel and 

 lumber. 



The effect of trees in preventing or diminishing the evaporation 

 from the ground caused by the passage of drying winds is far from 

 being j^roperly appreciated. We often speak of the effect of wind in 



