OONTSNTS, Vtt 



on Table Mountain, at the Cape of Good Hope, are adduced to 

 show that these, like the alleged attraction of clouds by forests, are 

 attributable to a reduction in the temperature of the air (p. 48). 



Chapter II — Effects of Forests on the Humidity of the Ground, 51 



Section I. — O71 the Wetness of Roads where these are over- 

 shadowed hy Trees, - - - - - 51 

 While the profuse evaporation from the trees through the stomates 

 of the leaves is net overlooked, the wetness of roads is traced to the 

 effect of the shadow occasioned by the trees preventing evaporation 

 from the overshadowed portion of the road (p. 51); in illustration 

 of which effect of shade are adduced experiments and observations 

 made at the Cape of Good Hope (p. 52), and observations on the 

 effdct of shade on ponds in England (p, 55). 



Section II. — On the Desiccation of Ground by Drying Winds 



being prevented by the Shelter afforded by clumps of Trees, 55 

 Illustrations are given of the effect of shelter in arresting evapora- 

 tion, and of the extent to which even bush may aci as a wind- 

 brake (p. 56). 



Section III. — On the General Phenomena of Evaporation from 



Forests, - - - - - - 57 



There are given indications of evaporation being retarded by forests 

 (p. 59), observations on the quantity of rain arrested by leaves 

 made by Marshall Vaillant (p. 61) and by M. Mathieu (p. 62), 

 observations by the latter on the different quantities of water 

 evaporated in woods and in adjacent open land (p. 63), and notices 



' of corresponding observations made by Risler(p. 61), with the con- 

 clusion from the whole that under the same measure of rainfall the 

 soil of the forest retains notably more water than does uncovered 

 ground (p. 65). 



Section IV. — On the Moisture being attracted from the Atmos- 

 phere, or otherwise retained in the Ground by Vegetable 

 Moidd, - - - - - - 65 



It is stated how it may be seen that there is a greater quantity of 

 moisture in the soil of a forest than in the soil of open country 

 (p. 65) ; illustrations are given of the process whereby such mois- 

 ture is absorbed (p. 65); the difference between this and the 

 deposit of dew is pointed out (p. 66) ; the property is stated to be 

 possessed in a high degree by clay and by vegetable mould (p. 67); 

 the latter is shown to be a product of forests, and a mode of deter- 

 mining the quantity of it in the soil is described (p. 70), and the 

 humus is shown to be liable to decomposition when exposed to the 

 rays of sun, unshaded by herbage and trees (p. 71). 



