DRAINING. 



79 



for which he sinks readily in the sand to the level of 

 the drain E. Below that is a quick sand, which can 

 only be excavated by dredging under water. His next 

 operation is to drain the springy bank below H, and, at 

 the same time, to get water at a high level, he makes a 

 tap drain H/<, and bores in the bottom, until he cuts 

 the open gravel of LHF, which furnishes a supply, 

 and relieves his ground. 



Suppose now the proprietor on the right wishing, in 

 like manner, for a supply of water, makes a tap drain 

 on his side, along the hill, as at F, but somewhat lower 

 than the level of H, and bores into the under stratum ; 

 the water of the hill HLF will now flow away at F, 

 and the drain H/i will be dry; but the land round H 

 will be somewhat better drained than before. Suppose 

 the proprietor at 1 1 still wanting a supply there, should 

 bore down through the stratum of clay EB, and into the 

 sand DC : instead of raising any water by that means, ths 

 whole supply of HLF will now run down through the 

 bores at H, into the sand DC, and pass away by the 

 drain Ee ; so that the ditch F/ will in its turn be dry : 

 Nevertheless a well or pump at F will always find wa- 

 ter in the tail of the bason HLF ; and if the bore at H 

 be below the level of the drain E, the supply may even 

 be more permanent than before, since it communicates 

 with the great bed DC. 



Lastly, suppose that the wet bottom on the right 

 hand is'to be drained ; for which purpose the tap drain 

 Gg is laid out, and bun - Mink into the sand DC. The 

 water will now rise up from the sand, and relieve the 

 quaggy clay al>ove : the springs in the bottom will cease, 

 and, what may appear still more remarkable, the main 

 drain EC beyond the hill will ebb dry, ami the quicksand 

 around will become firm and dry, as low as the level 

 AGB of the tap drain. The well at K may now be Mink 

 without difficulty ; but no water will be found until we 

 arrive at the clay, (above the level before mentioned,) and 

 even then only by cutting a reservoir in the clay, to re- 

 c'"ive a part of' the waters which trickle along its surface 

 through the bottom of the sand. No overflowing well 

 can now l>e madf in that situation, even should there be 

 strata containing water to a higher level below, which 

 might be Ixired into, unless a closo stciiiing or casing 

 be carried up through the sand lx?d DC, to prevent its 

 ebbing away by that channel through the drain G ; 

 but, before tapping at G, if we had inserted a bore at 

 m, which is below the level of E, we would have had 

 an overflowing well on the top of a hill ; and again, if 

 the stratum of clay at H were not yet cut through, we 

 would have at the same time another overflowing spring 

 at F, which would appear to be the hill from which 

 the fountain at m was derived. We have seen instances 

 of this kind in natural springs. It is worthy of re- 

 mark, that the proprietor on the right side dried like- 

 wise the grounds on the left, in the act of draining 

 his own ; and he could not avoid doing so. Similar 

 effects take place frequently in the drainage of mines ; 

 and when these are level free, they may be frequently 

 applied to the purpose of draining the lands above, by 

 boring down at H, or boring upwards from the mine. 

 But where the mine is drained by artificial means, as 

 pumps or the like, it becomes of the greatest conse- 

 quence to cut off and remove all supplies of water that 

 may enter from above. 



Suppose, for example, that DC were a bed of coal, or 

 other mineral, drained artificially at K, and that a shaft 

 were to be sunk at H, it would be necessary to pass 

 through the open stratum in the hill HLF : if this were 

 a quicksand, abounding in water, it might be very di< 

 2 



ficult to be effected ; and it would be necessary to in- Drainiflg^ 



troduce piece after piece of curb timber around the J""" TV T 



1 , . T, . Drvma ct 



shaft, to prevent the sand from running. Even it we jp^ng 



should succeed in getting down, the water would de- grounds. 

 scend through these timbers so abundantly, as to in- p LATE 

 crease greatly the water on the engine at K, and might CCX xxui 

 even drown the mine. The remedy, in that case, is to pig. n. 

 surround the leaky part of the shaft H with an inner 

 casing of timber, and a puddle wall of clay, Sec. behind 

 it, and to unite this puddle wall with the beds of clay 

 both above and below. The mine being then relieved 

 of foreign water, will be restored to its original state, 

 and will come again under the power of the engine. 

 But suppose the bed EB not to be so completely re- 

 tentive, but that water may penetrate through it when 

 the lower beds are laid dry, especially if it be pressed 

 by a great force, as the water accumulating in the hill 

 LHF, then it may be still possible to relieve it from 

 that pressure, by tapping, for example, at H or F, so as 

 to lower the head of water in the reservoir, which will 

 not then be able to penetrate through the bed EB, or, 

 at least, not so abundantly, and the engine at K will 

 be greatly relieved. Similar effects will also be pro- 

 duced, by having a catch-water dam, or puddle wall, 

 to lead off the water, which would otherwise be ab- 

 sorbed on the upper side of K, towards the crop of the 

 strata, as described in Figs. 8. and 9. A leaky stratum Fig. 8. & 9. 

 may be covered or lined with puddle, and secured in 

 a similar way. The writer of this article has puddled 

 the fissures of a leaking rock, and sunk shafts into it, 

 although situated under the water of an extensive lake. 

 Suppose again, that the proprietor on the right hand 

 at B intends to work his part of the bed of coal, and 

 to drain with engines by the shafts G or m. But that 

 the proprietor A, who will be equally or more benefited, 

 and whose engine at K will thereby become unneces- 

 sary, refuses to assist him. Then B, having no other 

 resource, places a powerful engine at G or m, and sinks 

 to the coal ; but he takes the precaution, after driving 

 his engine level along the coal as low as he can reach, 

 to make up the lower side of it with a puddle wall of 

 clay, &c. In like manner, he cuts out the coal along 

 all the boundary of his property towards the basset, 

 and replaces the excavation by water-tight materials, 

 so that all the water which formerly flowed in upon 

 him from the basset of the strata is now puddled off; 

 and he finds the drainage of the remainder can be ef- 

 fected by much less power, than was necessary for his 

 first engine at G. While the proprietor A, whose coal 

 at fir.t was laid level free, is now perhaps worse oft' 

 than before, since he is deprived of the benefit of springs, 

 that may have flowed at G, below the level of part of 

 his coal. Should there be absorbent strata in that di- 

 rection, and above his level, he will be benefited by 

 the puddling. A case of this kind occurred some time 

 ago near Edinburgh, and occasioned much litigation. 

 The l>eds of coal, and other minerals, are frequently 

 traversed by natural partitions of water-tight matter, 

 which are of great benefit in the drainage of the mines. 

 It is surprising how thin the partitions are, which re- 

 sist great depths of water in this way ; and which, 

 when they are incautiously broke through, are produc- 

 tive of great difficulty, and even danger ; so that it is 

 advisable, in all dubious cases, to make constant use 

 of the Ixjring iron, to discover them, as the hole which 

 is thereby made may be easily stopped up in case of 

 need. 



Puddling is also used in the digging of wells, to keep 

 out salt or mineral springs, which may flow into the 



