196 NATURAL HISTORY OF SELBORNE. 



LETTER XXIX. 



Selbohne, Feb. 7th, 1776. 



In heavy fogs, on elevated situations especially, trees are 

 perfect alembics ; and no one that has not attended to such 

 matters can imagine how much water one tree will distil in 

 a night's time, by condensing the vapour, which trickles 

 down the twigs and boughs, so as to make the ground below 

 quite in a float. In Newton Lane, in October 1775, on a 

 misty day, a particular oak in leaf dropped so fast that the 

 cart- way stood in puddles and the ruts ran with water, 

 though the ground in general was dusty. 



In some of our smaller islands in the West Indies, if I 

 mistake not, there are no springs or rivers ; but the people 

 are supplied v^ith that necessary element, water, merely by 

 the dripping of some large teak trees, which, standing in 

 the bosom of a mountain, keep their heads constantly 

 enveloped with fogs and clouds, from which they dispense 

 their kindly never-ceasing moisture ; and so render those 

 districts habitable by condensation alone. 



Trees in leaf have such a vast proportion more of surface 

 than those that are naked, that, in theory, their condensa- 

 tions should greatly exceed those that are stripped of their 

 leaves ; but, as the former imbibe also a great quantity of 

 moisture, it is difficult to say which drip most ; but this I 

 know, that deciduous trees that are entwined with much 

 ivy seem to distil the greatest quantity. Ivy-leaves are 

 smooth, and thick, and cold, and therefore condense very 

 fast; and besides, evergreens imbibe very little. These 

 facts may furnish the intelligent with hints concerning 

 what sorts of trees they should plant round small ponds 



