720 



PRACTICE OF AGItlCULTlKK. 



Part III. 



difficulty and expense, even where materials can be easily procured : while that of divert- 

 ing the current by a pier may frequently be accomplished at a comparatively small 

 cost; and its effect be rendered infinitely more salutary and permanent. For it is plain 

 that, if the accidental obstruction mentioned had been timely removed, no bad effect 

 would have ensued: and the river would have continued its direct course. Or if, through 

 neglect, it bad been Buffered to remain awhile, until its mischief was discoverable ; even 

 then, if it had been moved from its station to the opposite side of the river, and placed 

 in the part alfected, this small counterpoise might have recovered the balance of the cur- 

 rent, and directed it into its wonted channel; and, in almost any case, by judiciously 

 placing, in a similar manner, a pier or other obstruction proportioned to the magnitude 

 of the power to be counteracted, the like effect may be produced. 



4S64. In the use of piers great caution is requisite, for a very little reflection will 

 show that they are more likely to increase than to remedy the evil they are intended to 

 cure. We have seen the injurious effects of such piers on the Tay and the Dee ; and on 

 a part of the Jed near Crailing they are so numerous, that the stream is, to use a familiar 

 phrase, bandied about like a foot-ball, from one shore to the other ; behind every pier an 

 eddy is formed, and if the stream does not strike the pier exactly, a breach in the bank takes 

 place. Many of these piers have, in consequence, been taken down. The use of such piers 

 am only be justified where the obstruction, from ill-neighbourhood or some such cause, 

 cannot be removed from the opposite bank ; or where, as is sometimes the case, it arises 

 from an island of sand or gravel thrown out by the river near its middle, which, however 

 absurd it may appear, the interested parties cannot agree as to who may remove. The 

 case of buildings also being in danger may justify such a pier for immediate protection ; 

 but if such breaches are taken in time, a few loads of loose stones dropped in the breach, 

 as recommended by Smeaton, will effect a remedy without the risk of incurring or 

 occasioning a greater evil. 



4365. In the construction of piers, attention is required to secure the foundation, either by first throwing 

 in a quantity of loose stones, which the water will in a great measure dispose of so as to form a flat 

 surface ; or by the use of piles either under, or in single or double rows around, those parts of its base 

 in contact with the river, (fig. 672. «.) The elevation (b), where the current is not required to act with 

 great violence on the opposite shore, ought to be bevelled back on all sides exposed to the water, towards 

 the middle of the structure (c). In the most important cases stones are the only tit materials, and these 



-*=— U-: LiUll' 



should he regularly jointed and laid in cement according to the best practice of masonry. But, in 

 general, a case of wicker work, of the proper shape, may be filled in with loose stones, some earth, 

 together with the roots of such plants as 7'ussil'igo /'etas'ites, /Jlymus aren:mus, Galium, &c. These 

 will form a birrier of considerable durability for some years, and probably till the evil is so far subdued 

 that, when the wicker case decays, its contents will have sufficiently consolidated to effect the object 

 without further care. If not, the wicker case may be renewed. In ordinary cases,- a mere wicker hedge 

 projecting into the water will effect tht object without further trouble. 



436fi. The sheath, or land-guard of loose stones, which Marshal recommends, and 



which, in effect, is the mode already mentioned (43(72.) as preferred by Smeaton, is 



applicable to the following cases : — First, where the river, in the part required to be 



bent, is confined, by rocks or otherwise, to an unalterable channel, as it frequently is 



in subalpine situations ; and, secondly, where a deep pool occurs in that part, at low 



