12S EFFECTS OF FORESTS ON MOISTURE. 



Reference is made to the Island of Ascension by Boussingault, in 

 his work entitled Economie Rurale considerie dans ses Ba2:)ports avee 

 la Ckimie la Physique et la Mineralogie, in a passage which has been 

 cited, in which he says : — " In the Island of Ascension there was an 

 excellent spring situated at the foot of a mountain originally covered 

 with wood. This spring became scanty, and at last dried up, after the 

 trees which covered the mountains had been felled. The loss of this 

 spring was ascribed, and rightly so, to the cutting down of the timber. 

 The mountain was therefore replanted, and a few years afterwards 

 the spring reappeared by degrees, and by and by flowed with its 

 former abundance." 



When I was at the Cape of Good Hope, the Hon. Mr Barrington, 

 of Belvidere, on the Knysna, wrote to me in regard to Ascension, that 

 on that island, the driest of the dry — spoken of sometimes as a heap of 

 cinders, which only could be maintained as a naval station by sending 

 to it water in tanks from England and from the Cape — trees and 

 culinary vegetables had been planted, and had been grown with 

 success, through instructions supplied by Sir Wm. Hooker from Kew ; 

 and that, since this had been done, not unfrequenlly had the island 

 been seen capped with a cloud, and little runneb of water had been 

 seen trickling down the sides of the rock. I have always understood 



mountains should be abandoned to forests and jungle ; and so cut them down, upon 

 which the water supply began to fail. Reflection soon taught the authorities the cause 

 of this failure ; upon which the hills were again planted with trees, and the rivers and 

 streams resumed their former dimensions," 



In the same letter the writer says :-" I have deferred answering your letter in the 

 hope of being able to consult some of the works which supplied a portion of the 

 material for my article ' On the Failure of Springs ;' but I have not been able to do 

 what I intended. What I say of the drying up of four hundred springs in Persia is on 

 the authority of Tavernier ; but as the copy I possess of that traveller has no index, I 

 cannot at once find the passage, though perfectly certain that it occurs in his account 



of the Northern Provinces Formerly, in my ' Manners and Customs of 



Ancient Greece,' (II, 370), I pointed out the disforesting of the mountains as the cause 

 of the drying up of streams and rivulets in several parts of the country, and of the 

 diminishing of nearly all the rivers. Demoeritus, many centuries before Christ, had 

 made the discovery that woods and forests are necessary to the maintenance of springs ; 

 and in the last century, Volney contended that the Sahara might be rendered fertile by 

 planting it with such firs as would grow in sand, which would attract and retain 

 moisture. I make not the least doubt that in the Transgariep portions of Southern 

 Africa, to which you refer, the diminution of moisture was occasioned exclusively by 

 the cause you point out, and not by any cosmical changes, as imagined by Livingstone, 

 Should the Government, as far as its authority extends, ordain that whenever trees are 

 cut down others should be planted in their place, and generally encourage the multi- 

 plication of woods and forests, I make no doubt that that whole region would be 

 abundantly supplied with moisture." 



