DRIPPING OF TREES. 231 



attended to such matters, can imagine how much 

 water one tree will distil in a night's time, hy 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 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, evergreens imbibe very little. These 

 facts may furnish the intelligent with hints concern- 

 ing what sorts of trees they should plant round small 

 ponds that they would wish to be perennial ; and 

 show them how advantageous some trees are in pre- 

 ference 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. 



