SPRING. 



It, being in general of much lefs depth than thofe of that 

 fubltance, the effeft is more quickly produced. Prefently 

 after a glut of rain, the fprings, in thele cafes, are faid to 

 fly out. Bc-fides, there is another difference, which is more 

 interelling, it is thought, to the prefent mquiry, between 

 the effefts produced by chalk and by fand, as conduftors 

 of rain or other water. Ciialk, for the moil part, throws 

 it out from the fides or at the bafes of the hills formed by 

 it, in clear ftrcams, producing no other cffeft on the fur- 

 faces of the lands than that of forming channels of convey- 

 ance for it to the rivulets or brooks, to which the particular 

 calt of furface may incline them. The waters abiorbed or 

 drank up by chalk-hills fc-ldom occafion, it is faid, any 

 thing of the nature of upland bog, unlefa when they rife in 

 the area of a flat-bafed valley, or arc impeded and obllrufted 

 therein, and by fpreading and ilagnating over its furface, 

 encourage the growth and decay of aquatic plants. On 

 the contrary, fand-hillocks are, it is iaid, fingularly produc- 

 tive of this baneful difeafe of land ; owing, in part, it is 

 fuppofed, to a want of uniformity in their internal ftruc- 

 tures, as well as of an evennefs of bafe, when compared 

 with chalk hills, which generally reft on impervious ilrata 

 of clay ; and likewife owing to the opennels of the texture 

 of the fandy material, which fulTera the contained waters to 

 fpread out and diilend themfelves freely in every direftion. 



Gravel is more porous, or condufts water Hill more 

 freely, than fand ; and is moftly found in thin ftrata or veins, 

 but lometimes in detached maffes, though very rarely in 

 extended hills. In fome fituations it is free from the ad- 

 mixture of any fort of earthy matter. In tliis condition it 

 condufts water as a pipe ; or when embanked with im- 

 pervious matters on every fide, contains it as a ciftern. 

 When a ftratum or layer of fubterrene gravel, or any other 

 free conduftor, is hipplied with, or h?.s defcending waters 

 coming upon it, it either condudls them to the furface, 

 leads them to a fountain, or, when the furface is too itrongly 

 guarded to allow of their efcape, ftores them up, and con- 

 fines them in quantity beneath the foil. Where the gravel 

 is partially depofited in veins, and tlie covering is thin, and 

 of an abiorbeiit or porous quality, the water, wherever it 

 approaches the furface, fills every pore of the foil, and 

 though unable to break its way out in a ftream, as a Itrong 

 fpring, occafionally trickles and percolates through it ; 

 thus encouraging the growth of fuperaquatic plants ; which, 

 being too grofs and unpalatable for pafturing ftock, fall 

 where they have grown, and, during a fucceliion of ages, 

 raife det.iched mounds of vegetable earth ; partaking, like 

 the moory bafii of fand-hlll vallies, of the nature of morafs. 



If the containing itratum or bed be more generally and 

 evenly fpread beneath the loil, and whore this is of an ab- 

 forbent porous quality, and moreover lo thin as to be eafily 

 permeable, as well as lying nearly level, a large extent of 

 ground may, it is faid, be rendered worthlefs, — may become 

 a mere morals, or extended bog. But if, under thele cir- 

 cumftances, the land lies with much defcent, the lower fide 

 only will be much affefted. Further, if the foil or cover- 

 ing, though of an abforbent porous nature, be conjointly 

 of a fufficient thicknefs and texture to prevent the contained 

 waters from rifing to the furface, an uniform breadth of 

 cold weak land will be produced. Where the covering is 

 not only thick, but impervious or noii-abforbent, fo as to 

 prevent the depreffed waters from rifiiig to the roots or 

 feeding fibres of field-plants, lands of a valuable quality are 

 met with : even when in the Ikate of perennial herbage, the 

 finer grades are, it is faid, produced ; but th.it, owing to 

 the coolnefs which fubjaccnt waters communicate to the foil, 

 in the early fpnng, vegetation ii more backward, and the 



produce lefj than it would be, if the caufe of the coolnefs 

 were removed by this mode of draining. Land of this de- 

 fcription is met with extenfively, and in great abundance, 

 on the flopes, and at the bafes ot the rifing grounds, in al- 

 molt every vale-dillridt of the kingdom. 



Pebbly matters, which are a common fubftratum of land, 

 it is faid, in the more mountainous parts of the country, aft 

 in a fimilar, but more complete manner ; being a ftill more 

 free conduftor of (ubterraneous waters than gravel. 



The manner in which chalk conducts fubterraneous water 

 to the fea, without injury to the furface of the land, is feen 

 above ; and open rock, fand, gravel, or any other porous 

 or condufting material, either iingly or in conjunftion, have 

 the fame effeit, when they form a free and continued con- 

 neftion between it and the furface of the open abforbent 

 lands. Cut the fame fubllrufture, when fituated at a dif- 

 tance from the fliore, and cut off from all fubterrene com- 

 munication with iko lea or other waters, by the intervention 

 of impervious or repellent matterr, produces widely dif- 

 ferent effefts ; and is capable of doing much milchicf to the 

 lower lands which more immediately iavell it, as well as to 

 thofe clofe around it. In thefe circumllances, the fubfiding 

 waters, unable to find a paffage downwards, fill every fif- 

 fure, crevice, and pore ; continuing to colleft, until the 

 furface of the embodied waters reaches fome friendly porous 

 ftratum, to conduit the overflow horizontally towards fome 

 open outlet ; or until the coUeftion has gained a fufficient 

 afcendency and weight to break its bounds, and force its 

 way to the furface, or blend with the fuperficial waters. 

 The bottom of a lake, or the channel of a deep-funk river, 

 firll offers the means of relief, in many cafes ; and it is not 

 unufual to fee fpring-waters curling at the furface of a deep 

 river-pool. In many fituations, it is fuppofed probable 

 that rivers receive larger fupphes from their own beds than 

 is evident to the eye of common obfervation. Where the 

 river-bed is fliut againlt them, the impounded waters na- 

 turally continue to rife, until they reach an open ftratum 

 of the lands on its banks, and thus effeft their efcape. 

 Where no fuch condufting ftratum offers itfelf, deep cleft 

 dingles and narrow dells, branching out of the riveted 

 valley, or wider vale, may, it is faid, be confidered as the 

 next places calculated for giving vent to rifing waters : and 

 here they are not uncommonly found boiling up through 

 beds of fand or gravel, or the fliattered fragments of rock ; 

 and by fpreading, in a ftate of nature, over the bafe of the 

 dell, give rife to moory grounds ; or iffuing from its 

 banks, give birth to a more aftive ftream. No deep funk 

 dell occurring, or any abforbent ftratum of the vale lands 

 being ready to receive the internal waters, or, having re- 

 ceived them, being unable to give tliem vent, by realon of 

 their being clofed on their lower margin or border, the fur- 

 face of the embodied waters necefiarily continue to rife above 

 the bafe of the hill, until, having reached a proper con- 

 duftor, a fpring or fountain ia formed ; or meeting with a 

 defcending fubftratum of abforbent or porous matter, it 

 enters it with the efteft of defcending waters, and produces 

 different forts of wetnefs according to circumllances. On 

 extenfive continents, and even in the interior parts of this 

 iflaiid, inftances of a fimilar nature mult neceffarily, it is 

 faid, frequently occur. 



It may be alio noticed, that it mull likewife not unfre- 

 quently happen, that witers which have been abforbed by 

 the porous materials of high lands are checked in their de- 

 fcent, before they reach tlie bale of the hill or mountain 

 which has imbibed them ; in the interior ot which, it is 

 more than probable, minor relervoirs are formed by rifing 

 waters, aud there adt in a fimilar manner to thofe which are 



{ormed 



