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 rivers appears from a
well-known fact in North America; for, since the woods and forests
have been grubbed and cleared, all bodies of water are much
diminished; so that some streams, that were very considerable a
century ago, will not now drive a common mill.* Besides, most
woodlands, forests, and chases with us abound with pools and
morasses; no doubt for the reason given above.
(* Vide Kalm's Travels to North America.)
To a thinking mind few phenomena are more strange than the state
of little ponds on the summits of chalk-hills, many of which are
never dry in the most trying droughts of summer. On chalk-hills I
say, because in many rocky and gravelly soils springs usually break
out pretty high on the sides of elevated grounds and mountains; but
no person acquainted with chalky districts will allow that they ever
saw springs in such a soil but in valleys and bottoms, since the
waters of so pervious a stratum as chalk all lie on one dead level,
as well-diggers have assured me again and again.
Pages:
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321