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having been previously determined on, three higher, above the neighbouring land, and the feet is generally left to be supplied by the pud- top-water level reaches within two feet of the top dle-lining. In cutting down the slope, all ex of the dike. The difficulty of keeping in the traneous matter should be carefully taken away, water, in such high embankments, must be great, such as roots of trees and plants; all vermin where nothing but earth is applied for the purholes should be well stopped and secured, and pose; but the Dutch puddle appears to make a indeed every thing which is thought at all likely complete barrier. The writer of this article has to disturb the coating about to be added ; and examined the principal dikes in Holland and the when ready it should be worked down quite Low Countries, and he invariably found they straight by the excavator's spade, and rendered were coated with puddle, and in a similar manner tight and sound. After so much is done, the to the way described above for weak or infirm lining may be proceeded in, which consists in embankments, except, perhaps, that they are spreading on a coat of the puddle, varying from more neatly done than with us, and they use a seven to twelve inches in thickness, all through kind of marly clay in the compost, which is often the canal line, which is ready to receive it; and rejected by our engineers. Indeed, canal making, when this coat is properly laid, and to the satis- in Holland, is a system interwoven with the faction of the resident overseer, it should be nature of the country. It would be a complete sprinkled with water, and remain till the following swamp if it were not for the canals: they perform day, when a second coat should be added, and so the double purpose of facilitating inland navigaon, till the coating has assumed the necessary tion, and draining the country. and required thickness; and when done it should Plate I. fig. 1, ENGINEERING, is the section of be neatly smoothed down, and the water may be a canal, showing it under circumstances of level let into the canal.
cutting. AA the line of the contiguous ground; The necessity of particularly attending to the B, B, the artificial embankments; C C the width puddle-lining cannot be too much impressed of the cut at top, and D D at bottom. The upon all those who may be concerned in canal external slopes can be so formed as to be used works. Leakage in a canal is attended with so for the towing paths. With respect to the slopes many embarrassing consequences ; among them, C, D, they are determined upon the principles loss of water is not the least, dilapidations of the already stated as prevailing among our best enembankments, and perhaps their being wholly car- gineers for that purpose, viz. for every foot in ried away; for when percolation takes place, and depth, giving a horizontal base of one foot and that througlı made or artificial ground, its solidity a half; and it follows, from such received data, is of very short duration. Nevertheless, it is that a canal six feet deep will require its sides to but too often carelessly done; and this circum- be sloped three feet, and, if it should be eighteen stance has led to an enormously extra expense, feet wide at the top water level, it would be besides disgust in the contiguous land-owners, fifteen feet at the bottom : hence may be deduced who have found their grounds constantly inun- very useful proportions for canals of greater didated by the leakage.
mensions, in which may be combined the pracA canal is said to be performed by level cut- tice found of utility in the smaller ones. ang when the natural state of lands through Canals are cut through so many variations in which it has to pass is tolerably level, and ap- the ground's surface, that it would be impossible proaching to a good summit-level to the next to anticipate them all: it is intended here, howlocks, both above and below it; when a line is ever, to notice two other cuttings, which will, to be cut through such grounds, nature is said to in some measure, allow of great extension of favor the undertaking, and it is, perhaps, truly application. When the ground slopes down to said, for in Flanders and Holland the canals the projected canal line it is called side-lying ; require no other consideration than in performing and, if a canal be forming through such ground, them in this way, and in them few locks are the work is said to be doing in side-lying ground. required, as a good summit-level may be accom- Plate I. fig. 2, shows the section of a canal for plished by embankmen's, which are there called such cutting. AA the sloping line of the dikes. These, io countries like Holland, are of ground ; B, B, the embankments to be raised : great consequence, and are commonly made wide C C the width of the cut at top, and D D the and handsome, planted with rows of trees on width at bottom. It is of some importance to so their sides, and sometimes even paved; they are, arrange the cutting, that the ground excavated in fact, the high roads of communication between from the canal be equal to make up the embankone part of the country and another, and afford ments on its sides : it is impossible that it should to the public the greatest accommodation, in be so in all cases, but a great expense may be giving them a dry and commodious road through- saved if a calculation be made of it previously to out the year, which could not otherwise be easily setting out the summit-level of the work, as then obtained in such swampy lands, which are more the removal of the soil may be wheeled to the than half the year overflown by the swelling of parts where it is most required, which will prethe Rhine, and the consequent increase of water vent heaps collecting about the works, which in the canals.
generates slovenliness, and sometimes the greatest The Dutch have the credit of having invented inconvenience. Deep cutting arises when the the compost or puddling: it is true, their canals canal approaches a hill, or the side of one, which are all so lined, and indeed without it, in canals it is intended to pass by deep or open cutting, such as theirs, it would be totally impracticable rather than by tunneling. Plate I. fig. 3, repre. to prevent their leaking. Their embankments, sents the section of a canal by deep cutting; or dikes, are sometimes raised twelve feet, or AA the inclined ground to be passed ; CC, VOL. VIII.
width of canal at top, and D D the width at out for such work in canals. Every reservoir hottom; the sets-off I, I, are generally appro- should be furnished with a gauge, indicating priated in such cuttings for the towing-paths, exactly the quantity of water that it can supply, and are called by the navigators berms. They '&c.; if the gauge be a wooden post fixed in the are also found to be exceedingly useful as a pro- reservoir, it might be accurately divided, so as to vision to prevent the loose ground which rolls show, by its divisions, the water lost by evapodown from the upper banks B and C from falling ration, or taken for the canal; and this gauge into the canal. It is in cutting in such situations would exhibit at once how the supply kept pace that the ability of the engineer displays itself; with the consumption. In the event of an excess he has often to contend with all the difficulties of water flowing into the reservoir, which cirof a bad stratification, in which, frequently, the cumstance should always be anticipated in its percolating waters become so great as to stop construction, many plans hare been suggested the proceedings. In such cases, pumps are had for disposing of it; the most usual way, however, recourse to; but it sometimes happens, never- of providing for a ready exit to such excess, is to theless, that he has no place into which he can form a weir or weirs, sometimes called tumbling convey the superfluous water, or, if he has, he is bays, frequently at the corners, if the form of not sure that it will not increase his difficulties, the reservoir be square; if round, or a compound rather than remove them. To offer expedients figure, at such places as is best adapted to its for such circumstances is impossible; they must ready discharge. It will appear quite obvious, be met by the experience and resources of mind of that the size and number of the tumbling bays him to whom the work is confided, and it will must be regulated by the estimated quantity of be well or ill performed, in proportion as his ex water they may be called upon to discharge, or perience and talent predominate.
the greatest inconvenience may follow; as in the Canals of great traffic must be furnished occa event of their being too small or too few in sionally in their course with passing places. number, in great swells of the springs arising They consist in giving an increase of breadth to from unusual rains, &c., the sides of the reservoirs the water way of the canal, so as to admit of may be overflown, to the destruction of its banks boats resting by the way, without incommoding and perhaps to the effect of blowing up and carthe navigation; every canal has them, and the rying away the canal works in its neighbourhood. only precautions are, that they be made in as The construction of a tumbling bay consists in convenient places as can be, to promote the con- forming a vertical syphon in the embankment of venience of the traffic; hollow and low places the reservoir, composed of well-wrought masonry are generally selected as the most eligible, and or brick, properly cemented, to which a horinear to the locks and basins if possible. By zontal communication is opened by the side of such places being formed, the public derive ac- the embankment of the reservoir. The whole commodation, as it admits of a ready transit of workmanship should be done in the most comproduce and industry to the inhabitants in its plete and perfect manner; the bottom of the neighbourhood. Reservoirs to canals, in most syphon shouid enter a culvert constructed in a cases, are indispensable, in order to the keeping similar way, which culvert or drain should be up a supply of water in its line; they are arti- arched above and below, and be built upon an ficial collections, getting their water from every easy descent, so as to promote an easy discharge source in their neighbourhood; their size must of its contents. The culverts are frequently be regulated by the quantity of water they are carried under the bottom of the reservoir, in intended to contain, and that by the line of work which case it will be essential to keep them suffiwhich it may be intended to supply. They should ciently low to admit of the lining being thick be placed in situations so as to contain an enough to secure its water-tight qualities. In equable quantity throughout the year, and so cases in which rivulets or other streams are dicontiguous to the canal, as to admit of an easy verted to the supply of the reservoir, a somewhat communication with it at all times. Wherever different construction will be required than when the reservoir is to be constructed, all the varia- it is fed by springs; this difference principally tions of the ground's surface should be exactly consists in an alteration of the approach by noted down; the nature of the soil proved, in which the water is to enter; such water is preorder to ascertain, if bad and porous, where, and viously collected into a branch, or, as it is termed, in what quantity, lining or puddling may be re a feeder, which is in fact a canal of smaller diquired for it. The water fowing through all mensions than the principal one. This feeder is springs, brooks, and rivulets, which it is deter- constructed so as to promote a current in its mined to divert, to supply the reservoir, should waters to the head of the reservoir, which it be exactly gauged, and also the depth of the enters by a weir or gates, the sides or piers of rains which usually fall. All such particulars which should be formed of masonry, built on a being ascertained, the excavation may be com- piled foundation, in carrying up the work, which menced; the same process is to be followed as should be of large stones well joined, and the has been recommended for the same kind of walls battering back from the line of their base, work in canals. The sloping of the banks and somewhat curved in their whole height. The is made rather more oblique than is practised tops should be coped with broad slabs of grafor canals, commonly to every foot in depth nite or free-stone, dovetailed together, or well a horizontal base of two feet, and, if the exca- cramped. The bottom of the weir should be vation be in a strong clay, the horizontal base is formed by an inverted arch of masonry, well made as much as three feet. The lining is per- bed in strong clay or puddle compost. The formed in a similar manner to the way pointed gates should be made of strong oak, with lower
and upper sills, framed with rails and cross tity, in proportion to the opening and velocity. braces, fixed in the stone sides by bars of iron. The quantity of water required to be let out of An iron upper rail should traverse the top side of the reservoir may be regularly ascertained, by the whole. The gate or weir should be in height fixing at the head of the screw a pointer, and an a few inches above the summit level of the re- index above it accurately divided into inches and servoir, that the water from the feeder may flow parts; and, as the paddle is raised by the screw over the bar of iron attached to the upper sill, fixed to it, the pointer at the end sliding upon The reservoir supplies the canal by means of the index will show the quantity of water disa pipe of cast iron, or other metal,, or stone. charged upon every division of it as set forth; This pipe is furnished with a cock which works as at three inches in height, 317,952; at six on an endless screw, and is so adjusted as to inches, 630,730; at nine inches, 927,936; and so be easily turned by the overseer of the reservoir. in proportion to all the several proposed eleva
Mr. Longbottom obtained a patent for the tions. This specification concludes with directions construction of reservoirs (see Repertory, vol. 4. for forming smaller reservoirs, in which many p. 145), the only novelty in which was, he de- ingenious suggestions are developed. The repended for a supply of water to the rains falling servoirs here treated of have been considered as upon the earth's surface, which he proposes to formed by embankments, which, in porous soils, collect together into one or more reservoirs; the have been recommended to be lined with words of the patent run thus : ' my intention is puddling; in some, however, such embankments calculated to supply canals, ponds, sluices, towns, will not answer the purpose, in such cases the or any other place wanting water, by making re- whole must be walled with brick or masonry, servoirs upon high and moorish ground, or any, and if of the former, the greatest care should be other suitable place which are to be supplied in taken that they be well laid, and of great submanner following.' He adds farther, that'he stance, with puddle-linings behind them; the cefound that in twelve months there fall upon a ment should be of fresh stone lime (and if ground superficial foot of land 3.33 cubical feet of rain- instead of slaked with water the better,) mixed, water, exclusive of exhalation, so that upon a with sharp sand, and the mortar prepared for statute acre there fall to the amount of 145,054,80 use only as wanted. The walls should battei or thereabouts;' again, he says, 'I can convey back in their height, with a small curvature outwater falling upon 3500 acres into reservoirs : side, diminishing in thickness as they ascend, for instance, 'I make a reservoir of 100 statute and finish finally at the top to two bricks and a acres in the most eligible situation, from which half, The whole should be coped with granite, open drains, or sluices are made in the most with the meetings fastened by dovetails. If it. proper places for receiving water running from be determined to form the walls in masonry, the surface of the grounds in rainy weather, which, in some situations, may be eligible from which, according to calculation, will be nearly the abundance of stone at hand, the same plan equal to 5076 cubic feet per acre, or 91,800 in the form of the wall should be had recourse cubic feet per annum, brought into the reser-, to; and also, in previously lining the embankFoir, except in loss by soakage; this may be ments, the ashlerings should be in as large pieces done without any prejudice to rivers or mills. as may be conveniently obtained, and all venty The area of a reservoir of 100 statute acres is or bad stones rejected. The joinings should be 4,356,000 superficial feet, and the average depth as close as possible, with very little cement 9:75; the parts are not included, so that 4,356,000 between them: the whole should be coped, as is the area by 9, gives 39,204,000, as contained in directed before, for walls of bricks. Most of our the reservoir of reserved water. For conducting canals are supplied by reservoirs somewhere in such water into the canal or sluice, he says, “I their course, so that an engineer can scarcely anmake two aqueducts of stone or brick for con- ticipate a work of canal-making without feeling Feying the water out of the reservoir, from the that he may be called upon to exert his talents bottom when the water falls perpendicular from to the forming of a reservoir. Reservoirs that its surface into the space of a large circle of have been lately formed to canals are—one at stone-work, with which the openings of the aque- Ripley for the Cromford Canal; another at Milducts communicate; in each of these I fix a stone for the Grand Junction; also, at Ainsworth paddle or clough equal to an opening of fifteen for the Nottingham; at Marsden for the Hudinches by twelve inches, which is raised by a dersfield; at Littleborough on the Leicestershire screw fixed to it, and moving upright in a piece Canal. The Rudyerd Vale supplies the branch of iron fixed across at the upper part of it; upon of the Caldon and Mersey, and occupies upit is a square box including a female screw, ia wards of 150 acres, and is more than thirty feet which the other moves, which is turned round by high. The St. Ferriol reservoir to the canal four small hand-levers fixed to the square box, of Languedoc occupies a space of 590 acres; and wbich rests upon a small iron bar, which the walls of which are covered with ashlerings of raises the screw and also the paddle, to the fol- freestone. lowing heights, viz.: with an opening of three Locks, or pound locks, in the consideration of inches by twelve inches may be delivered 317,952 which many important circumstances develope cubic feet of water in twenty-four hours; with themselves in the work of a canal, are the barriers one of six inehes by twelve inches, 630,730 feet; by which the water is kept to its summit-level; with one nine inches by twelve inches, 927,936 in the several reaches on its line they also opefeet: with one twelve inches by twelve inches rate as toll bars for collecting the tolls payable on 1,222,560 feet; and one twelve inches by fifteen navigating it: they are placed as frequently on wiches, 1,512,000 feet, or a less, or a greater quan- the line of the canal as the several levels require