36 On the Changes of Temperature and Soit 
and extended through Germany and Poland. England wad 
proportionally lefs abundant in forefts. Now it may be 
readily comprehended what extraordinary cold, what moift 
and unhealthful air muft have prevailed in the climate of 
thefe extenfive countries, as all the mountains and plains 
were covered with fuch immenfe woods, and as each valley 
almoft contained a lake or a marfh; and what wonderfut 
changes i in the temperature of thefe lands muft have been 
effected by the extirpation of thefe extenfive forefts, and by 
draining off the fiagnant waters. Large woods prevent the © 
heanis of the fun front penetrating to, and warming the foil 
they impede alfo the free diffufion of the internal heat, as 
the fallen leaves and branches which rot on the. ground form 
a moift crn{t through which the internal and external heat 
can with difficulty force a paffage. In the laft place, they 
concentrate the cold and moift vapours, render them putrid, 
and corrupt the whole atmofphere. This has been always 
obferved in North America, as we are affured by Dr. Wil- 
fiamfon; and the confequences are bilious and intermittent 
fevers in fummer and autumn, and inflammatory fevers in 
winter. He afferts, that the opener and drier the land bes 
comes, the more it is remarked that thefe fatal difeafes de- 
cereale, This muft have been the cafe formerly in Europe 
under the like circumftances, and the like caufes muft have 
contributed to render its climate milder and more falubrious. 
The Celts and Sarmatians, who were the firft inhabitants 
of all the European countries lying to the north of Italy and 
Greece, like all the barbarous nations under different names 
which defecnded from them, and which over-ran the Roman 
empire in the fifth and fixth centuries, defpifed agriculture, 
and cultivated no more land than was fufficient to fupply the 
wants of the current year. They lived chiefly either on what 
they caught tr hunting, or the flefh of: their domeftic ani« 
mals, of whieh they reared a great many; as they confidered, 
though very unjultly, thefe employments as much nobler 
than the cultivation of land. Now it is certain that the cul" 
ture of the earth, which breaks its furface, puts it in moves 
ment, keeps it in a flate of continual tendernefs, and makes 
it!capahle of imbibing the rays of the fun In fammer, and of 
affording 
