76 NATURAL AND CIVIL 



were stagnant, and in such quantities as to b^ 

 spread over the largest part of the ground. One 

 of the first effects of cultivation is the dispersion 

 of these waters, and a change in the soil, from 

 the appearance of a s^vamp, to that of a dry and 

 fertile field. 



There are two ways in which cultivation 

 operates, to produce this effect. By the cut- 

 ting down of the trees, the dispersion of a vast 

 quantity of fluid, emitted by their evaporation, 

 is prevented ; and by laying the lands open to 

 the influence of the sun and winds, the evapor- 

 ation of the stagnant waters is greatly promoted. 

 The effect of the first, from experiments which, 

 will be related when the vegetable productionr* 

 are considered, may be estimated at three 

 thousand and eisrht hundred Q-allons of water 

 tlirown off from the trees on one acre, in the 

 space of tweh e hours, in hot weather. To as- 

 certain the efiect which miffht arise from the 

 latter, on June 27th, 1789, a fair, calm and hot 

 day, I placed a china saucer on the ground in 

 the woods, where it \wls covered from the solar 

 rays by the trees, the leaves of which at the 

 height of ten or twelve feet, were very thick. 

 Another saucer in all respects similar to this, 

 was placed on the ground in an open field ad- 

 joining, where it was fully exposed to the wind 

 and sun. I poured into each of them equal 

 quantities of water ; at the end of three hours 

 the evaporation from the latter, was to that from 

 tlie former, as six eight tenths to one. With 

 regard then to tlie moisture or wetness of the 

 country, it appears that settlement and cultiva- 

 tion will be suflicient to prevent the discharge 



