1»38] 



F A U IVl E R S' REGIS T E R 



81 



etone, a little vyay up the river, in the direction B 

 C, will (lirc.-til)c"curreul towards D, and i)reveut 

 any tartiier injury. 



A jutiy of this kind ought to be carrricd out in 

 an obliciue direi;tii»n, so asio Ibrce the current gra- 

 dually towards the intended point. If lijrnied too 

 nmcii at right angles with tlie stream, as at A. 

 Fig. 2, it will throw the stream with violence on 

 the opposite baid<. at B, from which it will revert 

 with dodt)le force upon C, the |^ice immediately 

 below the |)ier; so that, instead Oi diminishing, it 

 would increase the destructive effects of the 

 stream. Bui, if the jutty is placed obliquely as 

 at D, it will ibrce the current gradually towards 

 E; in which position, one juity may do niore 

 good, than several placed improperly at right an- 

 gles. It may be further remarked, tliat when a 

 pier is abruptly intruded into the natural channel, 

 it requires Iron, five to ten times more strength of 

 structure than one which deviates gradually i'rom 

 the direction of the stream: in the one case, there 

 is both the weight and force of the water, while in 

 the other there is merely its weight, to withstand. 

 And, above all, it is important to consider, that 

 by making the pier in the direction prescribed, it 

 cannot occasion any injury to the opposite bank. 



The materials for constructing a guide of this 

 nature, depend upon the magnitude of the stream 

 to be directed. Il" it be small, a ridge of stones 

 thrown loosely in may suffice; a barrier of this 

 sort is both cheap and eflectual, and when injured 

 by any extraordinary flood, is easily repaired. 

 When the land through which it passes is very 

 valuable, and in the vicinity of a town, and the 

 river is lanje and rapid, so that a pier of consider- 

 able height is necessary, it is proper if the expense 

 be not excessive, to construct the pier of stone and 

 mortar. In other situations, where masonry is 

 too expensive, and the ground of less value, it may 

 serve the purpose to employ casoons Ibrmed with 

 piles and planks, or strong cases of wicker-work, 

 and either of these filled vvith small stones or gra- 

 vel, in order to give them stability; and ihey should 

 be sunk along the edge of the banks, in as regular 

 and firm a position as possible. These last expe- 

 dients have been practised most successfully on 

 several parts of the river Spey, and at Carcston, 

 on the banks of the river South Eoi;, in Forfar- 

 shire. 



As the Spey is one of the most rapid and im- 

 petuous rivers in Scotland, and as the methods of 

 embanking it is have been various and expensive, 

 the following description of these operations, in 

 Us course through the Park of Gordon Ciistle, 

 where it most ungovernable, may be useful in 

 similar cases, and is given from the 'Agricultural 

 Survey of the County of Bantr.' 



"It is believed, that the Spey first began to 

 make encroachments on the skirts of the Park of 

 Gordon Castle in September 1768, by the vio- 

 lence of the highest flood which tradition has 

 kept on record. The first kind of embankments 

 which were thereupon attempted, weve expen- 

 sive bulwarks of stone, built by the mason, but 

 without motar. Their appearance, indeed, be- 

 spoke both efficiency and duration; but, like other 

 fair appearances, ''it smiled deceitful;'''' and, not- 

 withstanding the continuance of expensive ope- 

 rations, the river, frequently levelling the works, 

 maintained the contest with success^ and on the 

 whole, gained ground, when the opposing power 



was placed under the direction of the late Mr- 

 Smeaion, wlio, on a brief survey, disapproved of 

 all the costly bulwarks, and dirccle<i nothinii' more 

 expensive than mounds of stone, loosely thrown 

 together, almost at random, from the bed of the 

 river, with no other art than to be raised liigher 

 than the vvaier could, at any time, surpass, and to 

 form a sloping shore, shelving back fiom the chan- 

 nel of the river. The embankments construcied 

 on this principle, have been, almost to a wisli, 

 successful. The river, now is, as it were, entirely 

 suiidued; and the highest floods, all hough their 

 violence in a thaw be exasperated by heavy mass- 

 es of floatiiio: ice, hasten harmlessly along, dash- 

 ing onwards directly into the sea. 



"On some occasions there has been a depar- 

 ture in practice from Mr. Smeaton's theory, by 

 forming a kind of mole of stakes, in collateral 

 rows, to the breadth of four or six feet, driven 

 firm into the gravel by the powerful repeated" 

 strokes of an /ippropriate engine. The slakes 

 were bound together near the top by transverse 

 bars, and supported by stones thrown in to fill 

 up nearly all the vacuities. This kind of embank- 

 ment was more expensive tlian the former, al- 

 ihough the limber was furnished wiihout price 

 from the forest on the other side of the Park; and it 

 was less eflicient, because, instead of diminishing 

 the power of the stream upon the gradual shelv- 

 ing of the slope, it was increased by direct accu- 

 mulation againstthe perpendicular side of the moie; 

 and, instead of adding any depositions of gravel, 

 and turning the channel thereby to a greater dis- 

 ance from the shore, the torrent was brought to 

 bear harder on the pile, and any gravel which had 

 been lelt there before was swept bare of]'. The 

 ordinary bed of the river vras established along 

 the course of this kind of pier; and it somehow 

 not admitting easily of repair, brought the case 

 into a worse state, almost, than it had been before. 

 "To render this kind of mole efficient, there- 

 fore, it would be necessary to add also the shelv- 

 ing slope of stone along the base of the pile, 

 forming that gradually rising shore, which the 

 river itself, on some occasions, exhibits, and which 

 no power of the flood thencelorth ever injures; as 

 if nature would thereby teach us the only secure 

 mode of guarding against the robberies of the 

 torrent." * 



Vv'iien the pier consists of masonry, it has been 

 found prudent to throw in a number of large rough 

 stones against the foundation, in order to prevent 

 the stream fi'om undermining it. Opposite to the 

 head and outer point of the piers, piles should 

 also be driven into the channel, to break the force 

 of the water, and. secure these important parts of 

 the work fi'om dilapidation. 



There is another evil that piers are exposed to 

 during floods, of which it is proper also to take 

 notice. When the river surmounts the pier, the 

 bofLly of water which falls over, naturally scoops 

 out a pit in the ground behind, and undermines 

 the precipice over which it tumbles. This evil 

 may be wholly removed, by raising the pier so 

 high as to prevent any overfiill; but this is a reme- 

 dy too extreme to be olten advisable. The most 



* The author inspected these embankmets, and re- 

 portRd his opinion of several improvements, to the late 

 Duke of Gordon, when making a survey for the drain- 

 age of the Huatly Estate, in 1811. 



