On 7'aining Trees. 85 



the surface of the burning desert is a phenomenon not the 

 least wonderful in the geographical history of vegetation. 



In Cockburn's Voyages we find an interesting account of a 

 tree in South America, which yielded a plentiful supply of 

 water by a kind of distillatory process : this tree was met 

 with near the mountainous district of Vera Paz. The party 

 were attracted to it from a distance, the ground appearuig 

 wet around it ; and the peculiarity was the more striking, as 

 no rain had fallen for six months previous. " At last," says 

 he, " to our great astonishment, as well as joy, we saw water 

 dropping, or, as it were, distiUing fast from the end of every 

 leaf of ihis wonderful tree ; at least it was so with us, who 

 had been labouring four days through extreme heat without 

 receiving the least moisture, and were now almost expiring 

 for want of it." The testimony of travellers is too often 

 enshrined among the fabulous ; and their credentials either 

 altogether rejected by some, or at least received *' cum grano 

 salis." Bruce of Kinnaird forms the most remarkable 

 example of this kind, and the caricature of Baron Munchau- 

 sen consigned the whole to sarcasm and ridicule ; and yet the 

 time is come when the more remarkable circumstances and 

 phenomena mentioned by this traveller, verified by Lord 

 Valentia, Mr. Salt, &c., are received as well accredited facts. 

 The curious phenomenon mentioned by Cockburn finds an 

 interesting and beautiful counterpart in two plants ; namely, 

 the Calla aethiopica and Agapanthus umbellatus, in both of 

 which, after a copious watering, the water will be seen to 

 drop from the tips of the leaves ; a phenomenon, as far as I 

 know, not hitherto recorded. 



The great rivers of the continent of Europe have their 

 source of supply in the glaciers ; but many of the rivers in the 

 New World owe their origin to the extensive forests of Ame- 

 rica, and their destruction might dry up many a rivulet, and 

 thus again convert the luxuriant valley into an arid and sterile 

 waste ; carried farther, the principle extends to the great 

 features of the globe. What the glaciers effect among the 

 higher regions of the Alps, the Pinus Cembra and Z^arix com- 

 munis accomplish at lower elevations ; and many a mountain 

 rivulet owes its existence to their influence. It rains often in 

 the woodlands when it rains nowhere else ; and it is thus that 

 trees and woods modify the hygrometric character of a coun- 

 try : and I doubt not but, by a judicious disposal of trees of 

 particular kinds, many lands now parched up with drought, 

 as, for example, in some of the Leeward Islands, might be 

 reclaimed from that sterility to which they are unhappily 

 doomed. 



Vol. IV. — No. 17. d 



