CONDENSATION BY TREES. 229 



the twigs and boughs, so as to make the ground 

 below quite in a float. In Newton-lane, in Octo- 

 ber, 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 quan- 

 tity. 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 

 that they would wish to be perennial ; and show 

 them how advantageous some trees are in prefer- 

 ence 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 



