DEAINAGE BY ROOTS OF TREES. 203 



strata bj this mode of conduction, yet the precise condition of 

 soil which I have described is not of sufficiently frequent occur- 

 rence to have drawn much attention to this office of the wood. 

 In fact, in most soils, there are counteracting influences which 

 neutrahze, more or less elicctually, the desiccative action of roots, 

 and in general it is as true as it was in Seneca's time, that " the 

 shadiest grounds are the moistest." * 



It is always observed in the American States, that clearing the 

 ground not only causes running springs to disappear, but dries up 

 the stagnant pools and the spongy soils of the low grounds. The 

 first roads in those States ran along the ridges, when practicable, 

 because there only was the earth dry enough to allow of their con- 

 struction, and, for the same reason, the cabins of the first settlers 

 were perched upon the hills. As the forests have been from time 

 to time removed, and the face of the earth laid open to the air 

 and sun, the moisture has been evaporated, and the removal of 

 the highways and of human habitations from the bleak hills to 

 the sheltered valleys, is one of the most agreeable among the many 

 improvements which later generations have witnessed in the in- 

 terior of the ISTorthern States.f 



Recent observers in France affirm that evergreen trees exercise 

 a special desiccating action on the soil, and cases are cited where 

 large tracts of land lately planted with pines have been almost 

 completely drained of moisture by some unknown action of the 

 trees. It is argued that the alleged di-ainage is not due to the 

 conducting power of the roots, inasmuch as the roots of the pine 

 do not descend lower than those of the oak and other deciduous 

 trees which produce no such effect, and it is suggested that the 



* Skneca, Questiones Naturales, iii., 11, 2. See also Flint, Nat. Hist., 

 chap. Ixxx. 



f The Tuscan poet Giusti, who had certainly had little opportunity of ob- 

 serving primitive conditions of nature and of man, was aware that such must 

 have been the course of things in new countries. " You know," says he in a 

 letter to a friend, " that the hills were first occupied by man, because stagnant 

 waters, and afterwards continual wars, excluded men from the plains. But 

 when tranquillity was established and means provided for the discharge of the 

 waters, the low grounds were soon covered with human habitations." — Lettere, 

 Firenze, 1864, p. 98. H. C. Carey, a distinguished American public econo- 

 mist, has, in his different works, made many important observations to the 

 same effect. 



