DRAINING. 



81 



Drying of 



spring 



grounds. 



PLATE 



CCXXXIII 



Fig. 12. 



Draining, and the superabundant moisture will escape through 

 the flints in the pit shaft to the chalk below ; and if a 

 drain is carried into a limestone quarry, it is seldom 

 necessary to carry it farther." Agric. Rep. Hertford. 

 p. 66. 



A similar practice is recorded as common in Flint- 

 shire, where the well is left open, and railed round 

 against cattle ; and the reporter observes, that though 

 in this and many other instances, the top water esca- 

 ped through the pervious substratum, the effect might 

 have been directly the contrary ; he therefore recom- 

 mends the use of boring-rods, as the hole made by 

 them is easily stopped up. 



The employment of boring-rods for this purpose is 

 mentioned in the Report of Roxburgh, &c. 



We may here observe, that the filling up of these 

 pits with roots of trees, stones, &c. recommended by 

 some authors, is very injudicious. After incurring the 

 expence of making them, they ought if possible to be 

 kept clear ; and the filters necessary for that purpose 

 (of which the cess-pool already mentioned is perhaps 

 the best) preserved in a situation to be easily accessible. 

 The sediment may be removed now and then for ma- 

 nure, and that in the pit taken out by a boring dredge; 

 whereas the stones and roots could only be cleared out, 

 by drawing off the water, with great trouble and ex- 

 pence. We have seen a bottom of this kind drained, 

 by cutting horizontally into the open stratum, as GO, 

 instead of sinking a shaft to it ; and perhaps the best 

 way is to sink a deep cut or shaft, EK, near the edge, 

 until the gravel, &c. be mt at a proper level ; and from 

 the bottom of this to carry a drift horizontally towards 

 the bog, as the work in this way will be dry during 

 the execution. 



The next case for our notice, is that of grounds lying 

 on the crop or basset of the strata, instead of being to- 

 wards the clip ; the most remarkable effect of which is 

 the alternate beds of wet and dry soil thereby produ- 

 ced. 



Fig. 13. explains this situation, shewing a hollow in 

 which there are alternate beds of sand and clay, or the 

 like, dipping into the hill. This may be considered as 

 the dry side of the hill, and will, in general, be found 

 so, provided the different beds of sand have any lower 

 outlet ; for of course all the water they imbibe will run 

 off by that ; but if not, then the water, falling from 

 the summit O, will sink into, the bed of sand KMLI, 

 and fill it up like a dish, until it run over the lip at 

 K ; then, after keeping the surface K wet by soaking 

 along the soil, it will subside into the land FHGE. We 

 may suppose a little of the soil worn down from KH, 

 to form a cover at the lower edge of HE forming a 

 spouting clay. The water running over this, and wetting 

 the clay bed ED, subsides into the sand DB, which, be- 

 ing nearly level at top, it completely fills. 



Lead up a drain across the different strata at the 

 lowest place, notching it pretty deep into the upper edge 

 of the clay, then the water running off from the sands 

 at lower levels, will not afterwards overflow. If it is ne- 

 cessary, carry a catch-water k k along the tail of the up- 

 per sand, which, cutting off the first supply, may perhaps 

 cure the whole. In the drain, at F, where the tail of 

 the sand has a covering of clay, sink tap holes in it ; 

 the lower sand DB, which is damp, must be bled by a 

 deep drain at B, so that this case is reduced to a modi- 

 fication of the former ones. It is sometimes unneces- 

 sary to continue the drain through the sand, since that 

 absorbs the water readily^ and it may be collected by 



VOL. vin. PAHT I. 



CCXXXIII. 



an arm, on either side at the lower edge, into the next Draining, 

 piece of drain which crosses the clay. Drake. 



Fig. 14. shews the case where the strata are vertical, 

 or nearly so, and have their edges in the face of the de- 

 clivity. The water will here subside through each of |j v 

 the open strata, and issue at its lower corner as a single 

 spring ; of course there will be a line of these springs 

 along the foot of every declivity, which are altogether 

 unconnected with each other ; and as the foot of the de- 

 clivity will be covered to some height with the rubbish 

 of the strata above, quicksands and quagmires may 

 be formed thereby. The remedy is to bring up a cut 

 for a tail drain B A, to run a drain along under the level 

 of the springs, and then to make small cuts into every 

 spring all at a proper level in the subsoil ; or if the 

 ground be spouty below them, to sink a tap hole below 

 each spring in the direction of the stratum. 



These different cases comprehend only the simpler 

 situations which are likely to occur in the practice of 

 draining; but, if well understood, they will be sufficient 

 to direct the operations required for the most complica- 

 ted. It sometimes happens, that all the different kinds 

 of draining are required in one field ; at other times, 

 this great complication is only apparent, as in Figs. 10. 

 and 12, and one drain, judiciously directed, will do more 

 than a great number run merely at random without 

 previous investigation. The first thing required is a 

 careful examination of the strata ; and indeed no per- 

 son can pretend to skill in draining without some degree 

 of geological knowledge. The inclination of the strata 

 must also l>e examined, to judge how they are connect- 

 ed with the given site, and how a drain or bore may 

 be directed to reach the spring. It is proper, therefore, 

 to examine all places where the strata have been laid 

 bare, as in cliffs, river beds, wells, ditches, quarries, &c. 

 in the neighbourhood. Where nothing of that kind oc- 

 curs, the boring irons must be applied for the purpose, 

 or pits sunk in the soil. If the water rises in these, the 

 evil and its cure may be discovered at once, and a drain 

 opened ; but it would be very injudicious to do so with- 

 out such previous investigation. The figure of the 

 ground must also be considered, as that will lead to a 

 knowledge of the place where the watery bed bursts 

 out, or is most accessible, and where drains may be most 

 ad\i-iably placed. The probable supply of water may 

 also be known in this way. 



The spirit level is used for laying out the direction of 

 the drains, and calculating the expence of cutting them. 

 The height of water in the interior strata may also be 

 known thereby, by levelling from the neighbouring 

 springs and wells. A very useful common implement 

 of that nature is shewn at Fig. 1 5, being a kind of qua- p . 

 drant made with stout laths, which may be formed and 

 graduated any where. (A. N. ) 



DRAKE, SIR FHAXCIS, one of the most distinguished 

 naval commanders and navigators in the reign of Queen 

 Elizabeth, was born of obscure parents near Tavietock, 

 in Devonshire, in the year 154.5. He was the eldest of 

 twelve sons of an honest seaman, and was brought up 

 in the sea-service from an early period of life, under 

 the care of his kinsman, Admiral Sir John Hawkins. 

 At the age of 22, he was appointed captain of the Ju- 

 dith, in the Gulf of Mexico, where he distinguished 

 himself greatly in the operations against the Spaniards. 

 In the year 1570, he made an expedition with two 

 ships against the same people ; and having improved 

 his fortune, as well as enlarged his experience, he sailed 

 a second time in 1572, with two ships, one of 7- r ', and j 



L 



