OF SELBORNE. 193 



feet 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 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 habitable 

 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 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 ever- 

 greens imbibe very little. These facts may furnish the in- 

 telligent with hints concerning what sorts of trees they should 

 plant round small ponds that they would wish to be perennial; 

 and shew them how advantageous some trees are in preference 

 to others. 



Trees perspire profusely, condense largely, and check 

 evaporation so much, that woods are always moist : no 

 wonder therefore that they contribute much to pools and 

 streams. 



That trees are great promoters of lakes and rivers appears 

 from a well known fact in North- America ; for, since he 

 woods and forests have been grubbed and cleared, all bodies of 

 water are much diminished ; so that some streams, that were 

 very considerable a century ago, will not now drive a common 



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