90 NATURAL AND CIVIL 



with the e\aporation ^^hich takes place from the. 

 woods, during the summer months. Every 

 tree,' plant and vegetable, is then pouring into 

 tlie atmosphere, an amazing quantity of fiuid. 

 On the 12th of June, 1789, 'l put the end of one 

 of the limbs of a small maple tree, into a bottle 

 containing about one pint. That part of the 

 limb which i^-as within the bottle, contained two 

 leaves, and one or two buds. The mouth of 

 the bottle was stopped ^^■ith beeswax, that no 

 vapour might escape. In fi^'e or six minutes, 

 the inside of the bottle wos clouded, "\vith a verv 

 fine vapour ; and in about half an hour, small 

 drops began to collect on the sides, and run 

 down to the bottom. At the end of six hours, 

 I -weighed the Vv'ater ^\hich had been collected 

 in the bottle during that time, and found it a- 

 mounted to sixteen grains, troy Vvxight. The 

 tree on which this experiment v/as made, was 

 eight inches and an half in diameter, and thirty 

 feet in heiHit, To make an estimate of the 

 quantit)' of -water, thro\vn oft' from this tree into 

 the atmosphere, in a given portion of time, I 

 endeavoured to ascertain the number of leaves 

 which it contained. With this view (after I 

 had made some other experiments) I had the 

 tree cut do\vn ; and was at the pains to count 

 the leaves, which it contained : the whole num- 

 ber amounted to twenty one thousand one hun- 

 dred and ninety two : Admitting the evapora- 

 tion to be the same from the other leaves of the 

 tree, as it was from those on which the ex'peri- 

 tnent was made, the quantity of water thro^A'n 

 off from this tree in the s})ace of twelve hours, 

 ^VGuId be three hundred and thirty nine thou- 



