SPRING. 



which a filter is to be formed with Iieatli and gravel, or any 

 other fubllancei which will prevent earthy matter, or water 

 in a foul ftate, from entering the (haft or opening. The col- 

 lefted waters are to be led to this filtering drain or opening 

 in all cafes. 



Where, however, the water is collcfted by means of co- 

 vered drains, and where the filtering parts have likewife co- 

 verings placed over them, the whole proccfs will, it is faid, 

 be free from external injury ; and drains or works of this 

 kind might, it is fuppofed, remain unimpaired for ages, or 

 a very great length of time. Even if the waters were col- 

 lefted by open drains, and the filters, or filtering parts of 

 them, were fuffered to continue in a Hate of neglect, until 

 the (haft, in the courfe of time, (hould become defeftive, 

 the remedy, it is thought, would be eafy ; as by embracing 

 a dry feafon to re-open it in, and to clean it, as well as the 

 materials with which it may have been filled, from their im- 

 purities, it may be rellored to its original condition at but 

 little expence or trouble. It may be noticed further, that 

 where the land to be drained and improved is liable to have 

 any other furtace-water coming upon it than what falls upon 

 its own fpace, fuch waters ought to be drawn and condufted 

 away from it fuperficially, by cutting it off at fuch a height 

 as will gain a fufficient fall. And further, when the quan- 

 tity of water which defcends into it fubterraneoufly, or 

 which would defcend into it if a free paffage were opened 

 for it, is found to be too copious to be readily difcharged 

 by fuch a drain or (haft in the manner here propofed, proper 

 means (hould be taken to cut off the fupply, or as much of 

 it as may be, by making a perforated trench, or otherwife, 

 at a fufiicient height to be able to convey it away in a fupcr- 

 ficial manner ; and with a fuitable fall, fo as to prevent its 

 entering the fpace of land to be improved ; which by this 

 means will only have its own fuperfluous waters to difcharge 

 by the (haft-drain. See SHAFT-Drain. 



There are many inltances of low, flat-lying, moory val- 

 lies in different diftrifts of the kingdom, and efpecially in 

 Norfolk, from the bafes of which it would be difficult to 

 make fuperficial drains, which have for their fubftrata or 

 fubftruttures, mod probably, infatiable beds or depths of 

 fand, or fandy matters, in which this mode of draining 

 might, it is (aid, be praftifed with vafl benefit. The 

 praftice in thefe cafes al(b affords additional explanation of 

 what has been faid above, in fpcaking of the removal of the 

 wetnefs of land by perforating through a retentive ftratum 

 to the porous one below, as well as the nature of the 

 drainage in bogs arifing from fprings. 



In cafes where the fuperficial foil is impervious and repel- 

 lent, or porous and abforbcnt, the fubfoil being uniformly 

 abforbent, but clofed in the bottom part, and charged with 

 rifing waters, the cfFeft produced varies in fome mcafnre 

 with the nature of the furcharged lands. Where the ab- 

 forbent fubftrata are imperfedly clofed, or where the fur- 

 charging waters find fome other partial vent at the fame 

 level, the effeft is merely that of an under foil, which is 

 liable to be faturated in a wet feafon, and which is left dry 

 after a long continued drought. But where the fubfoil of 

 the land to be improved, together with the fubftrata in its 

 vicinity, on the lame level, are equally impermeable, and the 

 tmliatiied waters are, in confequence, under the ncccflity of 

 rifing, for a vent, to a higher level, the lower lands become 

 fubjefted to perpetual furcharge : even the furfacc-foil, 

 when in any degree abforbent, becomes liable to a fimilar 

 degree of faturation, by reafon of the weight of water 

 which lies above it ; as the comprefl'ed waters, adling in 

 conformity to the general law of fluids to gain a common 

 level, prefs upwards againll the foil : and where this is freely 

 Vol.. XXXIII. 



and uniformly abforbent, it becomes fully faturated ; the 

 inevitable effect of which is a bed of fuper-aquatic plants ; 

 and, in the courfe of time, an extent of deep moory bog : 

 if partially abforbent only, plots of moor are the con- 

 fequence. 



The means of relief in cafes of this nature are much the 

 fame as thofe in the firft of the above cafes. Where the 

 fubfoil is uniformly free, and a fupply of water is not 

 wanted above what is called the running level of the lower 

 margin of the land to be improved, a trench, with a fuffi- 

 cient outfall there, will lay the whole effeftually dry ; and 

 will, in addition, become the common outlet of the internal 

 waters ; iiiltcad of the naturrl fpring, which will confc- 

 quently ceafe to flow. 



But if, on the contrary, die fubfoil be not fufficiently 

 open to permit a free patlagc for water through it, or where 

 economical intentions demand a fall from the upper margin, 

 it will be right and proper to attempt to take off the head 

 and weight of the water, by a trench made at the foot of 

 the hill ; and then to free the fpace of land difeafed by one 

 or more drains, as the particular circumltances of the cafe 

 may direft. Where a fupply of water is particularly de-. 

 firable, or the improvement of cold land?, hanging on the_ 

 Hopes of rifing grounds, is wanted, it may be tlie moft pro- 

 per, when it is found that a deep trench alone, made at the 

 foot of fuch Hopes, by reafon of the too great depth ef the 

 impervious or repellent materials, is infufficient for the pur- 

 pofe, to try the effeft of the borer, and by this means en- 

 deavour not only to accomplifh the fupply of water that may 

 be defired, but by bringing down the furface of the fubter- 

 raneous coUeftion to a level with the bottom of the trench, 

 to relieve the plain below from the upward predure ; and 

 thereby probably remove the evil in a fufficient manner, 

 efpecially on the higher fide, without additional trouble and 

 expence. 



In cafes fimilar to the above alfo, where a freely conduc- 

 ing ftratum, which is charged with water, lies too deep to 

 be eafily reached by a trench, and too level to be relieved by 

 the borer, and in all cafes where the water lies too low, and 

 in too flat a fituation to admit of a fuperficial channel being 

 funk deep enough to draw it from its natural bed, yet 

 without an open ftratum beneath to render a (haft-drain 

 effeftive, a well-drain funk in the loweft part of the ground 

 to be improved, may, it is fuppofed, be had recourfe to with 

 good effect. See WKLL-Drain. 



In cafes where the quantity of water to be raifcd is con- 

 fiderable, and the depth at which it lies not more than fix 

 or eight feet, it may be forced up into an open drain, funk 

 to about half the depth, by the ufe of the common draining- 

 mill of mardiJand diftridts : or, where the depth is too 

 great, or the fuperftrata too loofe ai d unliable to admit of 

 a deep open drain, and that of an arched one too cxpenfive, 

 a pump wrought by wind, or by water, where a fufficient 

 ftream can be commanded, may be fufficient to raife it to 

 the furface ; care being taken in this, as well as the above 

 cafe, that no extraneous waters interfere. See Surface- 

 Draining. 



There are other cafes of draining bcfidos thcfe, in which 

 the wetnefs is removed by drawing off the fprings that caufe 

 them. See Tapi'ING Springs. 



Cafes of the fame nature as thofe given above are illuf- 

 tratcd by means of feftions, in all the different inftanccs, by 

 the writer of the work on " Landed Property." 



In many cafes too, a great deal is capable of being 



efTcftcd in thefe and other forts of hilly grounds, and very 



aftonilhing effects produced, in fome inftaiices, by means of 



cuts or drains alone, properly dircftcd, without the necefTity 



4K of 



