LETTER LXXI. 

 To THE Honourable Daines Barrington. 



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 con- 

 densing 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 cartway 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 with that necessary element, 

 water, merely by the dripping of some large tall 

 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 hab- 

 itable by condensation alone. 



Trees in leaf have such a vast proportion more of 

 surface than those that are naked, that, in theory, 

 their condensations should greatly exceed those that 

 are stripped of their leaves ; but, as the former im- 

 bibe also a great quantity of moisture, it is difficult 



to say which drip most: but this I know, that de- 



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