206 
NATURAL HISTORY 
century ago, will not now drive a common mill". Befides, mofl 
woodlands, forefts, and chafes, with us abound with pools and 
moraffes ; no doubt for the reafon given above. 
To a thinking mind few phenomena are more llrange than the 
flate of little ponds on the fummits of chalk-hills, many of which 
are never dry in the moft trying droughts of fummer. On chalk- 
hills I fay, becaufe in many rocky and gravelly foils fprings ufually 
break out pretty high on the fides of elevated grounds and moun- 
tains ; but no perfon acquainted with chalky diftrifts will allow that 
they ever faw fprings in fuch a foil but in vallies and bottoms, fince 
the waters of fo pervious a flratum as chalk all lie on one dead 
level, as well-diggers have affured me again and again. 
Now we have many fuch little round ponds in this diftriil ; and 
one in particular on our fheep-down, three hundred feet above my 
houfe ; which, though never above three feet deep in the middle, 
and not more than thirty feet in diameter, and containing perhaps 
not more than two or three hundred hogflieads of water, yet never 
is known to fail, though it affords drink for three hundred or 
four hundred fheep, and for at leaft twenty head of large cattle 
befide. This pond, it is true, is over-hung with two moderate 
beeches, that, doubrlefs, at times afford it much fupply : but then 
we have others as fmall, that, without the aid of trees, and in fpite 
of evaporation from fun and wind, and perpetual confumption by 
cattle, yet conftantly maintain a moderate fliare of water, without 
overflowing in the wetted feafons, as they would do if fupplied by 
fprings. By my journal of May, lyjs^ '^^ appears that " the fmall 
and even confiderable ponds in the vales are now dried up, while 
the fmall ponds on the very tops of hills are but little affeded." 
Can this difference be accounted for from evaporation alone, which 
certainly is more prevalent in bottoms ? or rather have not thofe 
« Vide Kalm's Travels to North- America, 
elevated 
