Under this head we shall commence with the drainage of towns and other inhabited places, with more particular reference to the removal and discharge of cloacal and other foul matters in a liquid state from human habitations.

We shall then notice the drainage of lands for agricultural purposes, and the drainage of fens, marshes, &c.

The first of these subjects has been already referred to in the supplement to Architecture (vol. iii.), and the remarks made in that place may be taken as introductory to the present article. For the drainage of fields for farming operations, see also Agriculture.

It was there shown that the removal of sullage by means of sub-surface sewers, whereby it has acquired the name of sewage, is of comparatively recent introduction. Towns are commonly built upon sites of which the immediate subsoil is permeable by liquids, and into which the excreta arising in and from human habitations have been discharged into cesspools formed in it; and no volatile and active gases are thrown out, under such circumstances, in quantities sufficient to produce any sensibly injurious effect upon the atmosphere. The gases which are evolved are deadly; but are comparatively innocuous while undisturbed. The foulness of old towns which stand upon dry sand or gravel, or other impermeable stratum of soil, may be referred rather to accumulations in and about the buildings of such corruptible animal and vegetable refuse as may not be thrown into the cesspool, and which cannot be made to pass away by drains; so that, in truth, effective scavenging is the first essential to wholesome ventilation, when excreta are dejected upon or into a soil which will absorb the liquids, and such must be the case indeed whatever system of sewering may be applied. It is not to be overlooked, nevertheless, that such soils as allow the liquid parts of excreta to pass away, do but filter them down into the water, for the sake of which, probably, the site was originally chosen, and that these liquid excreta are thus apt to reappear in the wells, and to poison one of the supports of life in another direction. But, however, disgusting this idea may be upon reflection, it does not always occur to the mind; and it is not until the close crowding together of human beings into the commonly small space which the original site of an old town comprises, that any effect really injurious to health can arise from that source; nor is it, indeed, to the source referred to that the most disgusting apprehension is traced, but to the deposit of the mortal remains of humanity within the strata from which springs of water are derived. Nor has the necessity of drainage, as a means of relieving towns of sullage, and of the exhalations consequent upon its exposure to heat and air, become recognised because of the defects of the system which retained the solids of human excreta within or immediately about the buildings in a town situated upon a bed of dry gravel, but because towns have outgrown their sites, and extended their buildings to the clay which so commonly occurs under beds of sand or of gravel. It has been seen that London has in this manner outgrown the limits of the gravel bed, and has been thrown upon the blue clay underlying the fine stratum of gravel which forms the banks and bed of the Thames in its course through London, and which comes to the surface at from one to two miles inland on each side of the river. No sooner was the clay touched by buildings, than the necessity of providing for the immediate removal of sullage became apparent; and in the endeavour to secure such removal by drainage in places where drainage is absolutely essential to allow of the occupation of the site for human habitation at all, a system deficient in a most important particular has been carried out to the serious detriment of those parts and places which had been already closely built over, and the air of which is injured more by the exhalations of the steaming sullage drain, than by anything emitted from a close cesspool dry-stained in gravelly soil.

But sewering will not supersede the necessity of scavenging, nor, indeed, if due regard be paid to the wholesomeness of the locality, ought sewering to be preferred to the dry cesspool, where a dry cesspool is available to the effect already indicated, unless provision be first made for scouring the contents away, and for removing directly to the upper air the gases which they will evolve in their passage.

It is obviously essential to the effectual relief of a town by drainage, that no building in or out of which matters requiring to be carried off by drains can arise, be built at so low a level, with reference to the eventual removal from the town of such matters, that the perfect drainage of the building cannot be effected by existing and available means of discharge; and no system of drainage can be carried out in any town lying low with reference to the outfall, unless provision be made by authority to the effect that when existing buildings cannot be otherwise fully relieved, artificial means shall be employed to relieve the low-level sewers.

It is further requisite to the effectual drainage of a town that there be such a supply of water to all buildings occupied for the purposes of life, that all matters entering their drains may be attended or be followed by water enough to carry the sullage onward without depositing in the drains, and that there be also such a supply of water to scour the main drains or sewers, either in a constant flow or in frequent and copious flushes, as will prevent the sullage from being arrested within them long enough either to deposit filth or to throw off noxious gases.

The fall of drains and sewers ought to be greater, and may be less, according to the provision available for scouring them, or of keeping up a current within them in any case. Half an inch of fall in every ten feet is the slightest permissible fall for a house-drain under the best circumstances; that is to say, when the supply of water to the house is so ample that the waste will certainly furnish a good scour therefore; but one, two, or even three inches of fall in every ten feet in length of such a drain may be requisite when the supply of water is scanty and the waste is likely therefore to be slack.

A fall of one and a half inches in every 100 feet in length is fall enough for a main drain or common sewer when it has a well-formed and evenly-built concave bottom, and when a constant flow of water, in quantity sufficient to prevent the sullage from depositing any of its heavier matters in the sewer, may be relied upon; but the fall should be greater when mere flushes of water are to be used as a means of carrying on the sullage. As regards size, house-drains and town-drains,—or private drains and common sewers, to use the terms more commonly applied to them—do not require to be of the large sizes of which they are usually made for the mere reception and conveyance of the sullage of the building, or of the town or district; but there are sufficient reasons why they should be made larger respectively than would be sufficient for those purposes alone.

It is a good general rule in all matters relating to constructions, that every part of any work liable, in its use, to derangement from any cause, be made accessible for the purposes of repair or of renewal. This rule ought to be especially adhered to in all matters relating to the drainage of buildings; whether it be of water, as liable to affect the structure, or of sullage, as liable to affect the health and comfort of the inhabitants; and what is true of a building is true of aggregations of buildings in a town.

But, in providing for easy access to whatever pipes and drains may occur inside a building, the arrangements to secure that object should be made in such manner as to occasion the smallest possible amount of inconvenience within the building whenever occasion may arise for employing them. And in like manner, as it regards the connexion of private or house drains with the main drains or sewers,—and as to the building and the repair of the sewers themselves, indeed,—arrangements should be devised to such effect that all such works may be executed without interfering, or with the smallest possible amount of interference, with any public way, or with the convenience of the public in the use of the public ways.

In providing for the relief of any place from superfluous waters, the first thing to be secured is an outfall or place at which they may be discharged, or otherwise so disposed of that they shall not return. An outfall must, therefore, be at a lower level than the place to be relieved, but it may be either natural or artificial. A country like Holland, or a place like the Isle of Dogs, east of London—the one fronted by a tidal ocean, and the other almost girt around... Drainage by a tidal river—finds natural vent for its superfluous waters at intervals, though at the expense of artificial works, and subject to whatever inconvenience may arise from the retention of the waters during the intermediate periods. The outfalls obtained in these cases are not such as would be chosen when better are obtainable, nor would such be rejected when they present themselves at a level available to the relief of the surface of a site, although they may not be at a level low enough to relieve subterranean conduits of whatever they may contain.

An outfall being obtained, whether it be natural or artificial, means are to be devised for collecting the liquid waste and bringing it together to the outfall for discharge. If this be so much below the level of the area to be relieved as to allow of fall enough in channels or other conduits,—and the receptacle at the point of discharge be such as to allow of such disposal,—the waste waters may be permitted to carry with them not only matters in solution, as culinary and cloacal refuse from the dwellings of men, but even the muddy washings of the streets of a town. If, however, the available outfall be not so low, or the eventual receptacle be not of such a character as to admit matters liable to deposit silt, prudence will dictate the propriety of keeping the foul matters, though solved in water, from becoming entangled with what may check their course to the outfall, and providing for the removal of the comparatively clean, though heavy dirt, being the street washings, by another channel. That is to say, a town situated on high ground and near, for instance, to the sea, may be relieved of its surface waters, the washings of its streets, and its sullage, being its cloacal refuse, kitchen and washing waste, by the same sewers without any inconvenience, and consequently at less cost than a town can be relieved of its waste under other and less advantageous circumstances, in respect of relative level of outfall and area to be relieved. In the case last supposed, a single system of sewers may suffice; but in the other case a double system ought to be formed, that the heavy and insoluble washings of the street may not mingle with and delay the solved and soluble domestic refuse.

Taking the more difficult case of a town of which the available outfall for its sullage is low with relation to the general area, the question naturally presents itself, what rate of fall is sufficient to secure relief, in the particular case contemplated, by or through the given outfall? And the obvious answer is, that the rate must depend upon the degree of fluidity of the sullage, and the condition as to smoothness or otherwise of the surface over which it is to run. Tar or treacle will not run so fast upon a surface of glass as oil will travel over a surface of lead laid at the same inclination; and water will make its way over a rough surface of brickwork laid with a like fall more rapidly than either of the viscid liquids can travel over the smoother surfaces assigned to them. The rate of inclination proper for drains or other conduits for the ready relief of a town of its liquid waste depends, therefore, firstly, upon the degree of fluidity of the waste, and, secondly, upon the condition as to smoothness of the surface over which it is to make its way to the outfall. Hence the objects to be aimed at when the outfall is bad, that is to say, high with reference to the area to be relieved, are to bring the waste as nearly as may be to the condition as to fluidity of unclogged water, and to provide drains the inside surface of which shall offer the least possible degree of resistance to the fluid by roughnesses or inequalities of surface, especially as regards the transverse section of the drain. It is to be borne in mind, at the same time, that although the fluidity of waste water, bearing sullage in solution, cannot be too perfect, having regard to the more effectual removal of the solved foul matters, the rate of fall may be too great for the conduits, whether they are open channels or covered drains. Open channels may be overfilled by a too rapid backwater, and the sullage run over before it has time to reach the outfall, as rivers are apt in their lower reaches to overflow by flushes of water coming into them too rapidly from their upper and more steeply inclined reaches; whilst in the case of barrelled or tunnelled drains, the sullage will be choked back to its source when the structure of the drains is strong enough to resist the pressure of the head that may be formed, or, the structure being weak the drain gives way, and a filthy bog is formed. Subterranean built drains, whether large or small, when they are well built of brick or stonework, and of substance enough to withstand the pressure of the ground about them, are generally found to be strong enough to resist whatever head may be formed by backwater hurrying down from upper reaches; but drains composed of pipes of pottery, or other substance strong enough, it may be, to bear the pressure of the ground, are weak at the joints, which commonly give way to a comparatively slight head of water acting within the drains, in which case the soil in which the pipes are laid is softened by the ejected liquid, the joints are drawn, and the above-stated result follows. But every part in the length of a drain is lower than the part above, and is liable, therefore—irrespective of obstructions arising from the casual presence within the drain, in any part below, of foreign and unconsidered substances—to be exposed to pressure from a head of backwater sufficient to destroy a weakly-built drain, or a pipe drain of which the joints are so weak as to be unable to withstand the pressure of a head equal to that of the overflow level at which relief may be obtained. But such relief to the insufficient or ill-disposed drain is purchased by the inhabitants of the place at which the overflow may occur at too high a price in annoyance to be suffered; and to avoid this contingency, all drains ought to be made large enough in every part to give free passage onwards, and to the eventual outfall, of everything that can pass into them under the most exigent circumstances possible in any case. And this consideration is irrespective again of that which regards the larger drains or common sewers under public ways, or near to heavy buildings, or elsewhere, at a great depth in the ground, which are with great advantage made larger than their purposes as conduits for waste waters might require them to be made, that there may be roomy access within them for workmen to form inlets from branches, to amend possible defects in the structure, or to remove casual obstructions.

It often happens that, as in the cases of much of the area of Holland, and all the Isle of Dogs before alluded to—except, indeed, as to the sea and the river walls or embankments respectively—the waste waters accruing within the area to be relieved between half, or even three-quarters ebb, and quarter or half flood of the tide in either sea or river, must be penned back in the sewers, or be lifted out by artificial power applied through pumps; and under such circumstances it is most important that nothing that can be deposited by the still waters should pass into the sewers. For in such case, it is no longer a removal of casual obstructions that has to be provided for, but a certain and often-recurring necessity of sending labourers into the sewers to collect and remove deposits which must always be foul, having regard to the company into which, when suspended, they had travelled, and always, therefore, offensive, and probably noxious upon being disturbed. No mere run of backwater as a scour will remove such deposits, even if they are a mere slime; but when they consist, as they commonly do, of grit and cementitious matter, they are apt to form a concrete that cannot be removed except by means which act upon the substance of the sewer itself, and tend to wear it out. The nidus of slime in sewers is soap-suds, a waste that must be allowed to pass by house drains, and so into and by the sewers; but it is only under the circumstance first above supposed that the washings of the streets of a town ought to be permitted to pass into the sullage drains. Drainage and sewers at all. It seems certain, therefore, that as a rule, the drainage of towns should be effected by a double system of drains—one part applied to the surface drainage being the rainfall upon the roadways, carrying with it the not necessarily offensive, but heavy and insoluble silt, the result of the wear and tear of the road material, and the droppings of gramminivorous animals used in the service of man—and the other part devoted to the relief of the particular habitations of men of liquid refuse, and matters soluble in water, but commonly offensive, and capable of becoming noxious, and requiring, moreover, to be led to points of discharge at or from which they may be dissipated. When a single system adapted to the former purpose only has been extended so as to include the latter, and a whole town has become inextricably involved in the vicious mesh, the best that can be done is to lead the commingled silt and sullage together to points of temporary lull, where the sand, the heaviest part of the silt, may deposit, and to draw off or pump out, as the case may require, and lead to the eventual points of discharge, the liquid sullage over it.

The practice of drainage, so far as regards the structure of sewers and drains, is mere matter of construction, and is both simple and easy. Drains as structures may be divided into three classes—the tunnel sewer drain, the barrel drain, and the pipe drain. There are varieties of each class, and the classes continually blend one into another, but the classes are, nevertheless, sufficiently distinct for general description.

The tunnel sewer is built of brick-work or of masonry, cylindrical or of some conic section in form transversely, and of such size that men may pass into and through it. The barrel drain, smaller in size than the tunnel, is in like manner built, and the best and most available form is the egg shape, with the small end downwards. The pipe drain is formed of pipes or tubes laid together in short lengths, various expedients being employed for connecting the pipes by their ends.

The tunnel sewer (and by the term tunnel a drifted or tunneled work is not necessarily implied) though simple in its form and of easy construction, is an important work of hydraulic architecture, and as such must be dealt with as a construction requiring to be laid or placed evenly upon a well-resisting foundation, and to be either sustained within itself as a bridge or as a church must be, or be so laid in the ground that it shall be pressed upon in every direction with reference to the power its form and the mode of construction employed may give it of resisting pressure for the security of its own structure.

The barrel drain must be laid, in like manner, on an unyielding foundation, and be so placed within and under the ground that the pressure upon it shall act in every direction alike.

What is above referred to as a pipe drain, may be a constructed barrel drain of the smallest size that can be built with brick in the form of a cylinder; but brick-built drains of small size, that is to say, of less than fourteen or fifteen inches internal diameter, will not be employed when pot-pipe of fitting kind and quality can be obtained, unless the drain is near the surface, and under a roadway exposed to heavy carriage traffic.

The use of tubes or pipes of pottery for drains is by no means new, but the removal of cloacal refuse from the habitations of man by underground conduits, whether as pipes or otherwise, is of recent introduction into the general service of towns; and of all the devices hitherto recurred to for such purpose there is none equal to pot-pipe rendered in absorbent by glazing. Such pipes may be made of sufficient strength to resist the dead pressure of the ground in which they are, for the most part, laid up to a bore of twelve or fifteen inches in diameter, and they may be and are made, with ease and economy, in lengths of about two feet, which length, indeed, cannot be much exceeded in practice. Elongated drains of pot-pipe involve, therefore, a multiplicity of joints; and as pot-pipe drains, as well as brick-built drains, are exposed to the intrusion of contemplated substances which tend to obstruct the free passage through them of legitimate matters, whilst pottery is very liable to be broken even in the laying and under the process of filling in over them, it has been sought to make the joints in such manner that they shall be water-tight, and at the same time easily opened and easily re-made. The common practice is to make them spigot and faucet fashion, or socketed, in rough resemblance to the jointing of a flute, one end of every length of pipe being widened out into a faucet or socket, and the other adapted to run into the socket, as the spigot does into the faucet; the hollow way being preserved when the joint is made. Such a joint in pot-pipes must be a loose one, and therefore not water-tight; and if it be packed with a cementitious mortar, the adhesion of the mortar will prevent the separation of the parts when occasion requires it, whilst in the rough workmen's hands the mortar is often pressed into the pipes, and dries into a hard and obstructive ridge, where the way should be smooth and free throughout. Mere plastic clay is used therefore to pack the joints, it being a substance easily softened and broken down into mud by the passing liquids; but it is also so weak against any force, that if from any cause a head of water or other liquid is formed within a socketed pipe drain, the clay soon gives way, the joints are, in technical phrase, blown; and the liquid is not merely let out, it is driven out into the soil in which the pipe is embedded. But, as it has been already intimated, pot-pipe is liable to be broken in laying the pipes—the liability arising mainly out of the process of punning or ramming the ground in, about, and over the pipes, after they have been placed and the joints formed. The consciousness of this liability, and of the equally mischievous result of ramming over and about such a structure as a pot-pipe drain laid in the usual manner in and on the naked earth, leads to a mere filling in of the earth about the pipes, and over them to such a depth that the rammer cannot be felt through the bed of earth, unless it be felt through the agency of a piece of gravel or a spall of hard stone casually dropped in over a pipe, by which from the blow above, a hole may be punched in the pipe, or the pipe broken throughout, and in either case the newly-formed drain is choked up, and made worse than useless. The more common case, however, is the blowing of the clay-stopped joints and the softening of the loosely packed soil about the drain, when the pipe sinks at the loosened joint, which is thus drawn, and the drain is a drain no longer. It is to be repaired—the floor must be taken up if the course of the drain is within a building, or the pavement above it if out of doors; and the ground is to be dug out along the line, until the point of failure be reached. The already loosened lengths of pipe are pulled asunder, or broken up if the small ends have been run too well up in the sockets, the penned-back filth in the upper reach obtains vent, and it is either allowed to go on by the hitherto unobstructed lower reach, carrying with it all of the sodden clay that it can render liquid enough to flow, or the filthy bog is baled out and carted away. The pipes have now to be relaid; but, as the joints are socketed, it is physically impossible to make good (as it is technically termed) without beginning at the beginning and taking up all the pipes above the fault to get lengths enough in again. Relaid in the same manner, the structure is liable to the same occurrence again and again; and whether the pipes are large or small, if they are no larger in the bore than barely suffices for the passage of the calculated waste, pipe drains laid upon naked and soluble soil—the commonest kind of soil—and jointed with soluble material, are all liable to the casualties above described. The foregoing observations have reference to one great defect in the pot-pipe system of drainage, but that one is in all essential particulars the result of a mistaken aim at cheapness. Pottery, like all other substances produced by or under the action of heat, is most liable to be defective at such parts of the thing produced as are larger in any particular direction. Socketted cast-iron pipes are liable to be unsound in the sockets where the metal is of different and unequal thickness and the body of greater extent in circumference, because of the unequal cooling of the metal; and socketed pot-pipes are liable to be unsound in the sockets, because the whole body of the pipe cannot, because of the socket, expand and again cool simultaneously throughout. Simple hollow cylinders, whether of iron or of pottery, are more likely, with the same care in the manufacture, to be sound, than socketed pipes of either substance; and for this reason, if for no other, pot-pipes should be simple hollow cylinders, and some other expedient ought to be employed for making the joints than that by which the pipe is liable to be rendered both unsound in its manufacture, and impracticable when the work requires to be repaired. Expedients have been devised to this effect, and are gradually making their way into use; while, at the same time, the mischievous influence of a bad practice is shown by that which is immediately superseding it—the practice of cutting off half the round of the socket, so that any one length of pipe may indeed be taken up and relaid without disturbing any other length, but the effect of the operation upon the pipe is that the part of the socket remaining detracts more than the whole socket does from the soundness of the structure of the pipe, and the upper half of every joint remains uncovered.

But the soundest pipes jointed in the soundest manner will not produce a sound and certainly effective drain without truth and stability in the construction of the drain. The exclusive advocates of pot-pipe drains, which they endeavour to distinguish by the term tubular, stigmatize brick-built drains as sewers of deposit. This, however, is absurd, since the same cause which renders brick-built drains occasionally faulty in their course does the same by the pipe drain, with this difference against the latter, that whereas the brick-built drain is of the same kind of structure throughout, and strong enough to bear the rude process of filling in, and is essentially larger than the pipe, whereby a deposit in a casually depressed part is not necessarily an impracticable obstruction to the course of the drain, nor is a head of water above such a defect the certain means of destroying it. The pipe is laid in lengths—weak in the joints—both weak and fragile in its structure, and liable to the defects above described when defectively constructed. But all that either brick-built sewers or pot-pipe drains require, when good materials and skilful workmanship are employed, to make sound, effective, and trustworthy conduits, free alike from liability to be choked or blown by water or by liquid waste, are an unyielding and even foundation, a firm seat, and truth in the setting of the work. All this is easily attainable, and is commonly attained in the modern practice of building sewers of brickwork. The broader base afforded by brickwork will find a resisting foundation upon a soil into which a mere pipe of the same internal capacity would sink; and a brick structure will bear the ground to be forced in around and above it by a process that pot-pipes of the strongest make may not be exposed to. But if, instead of a false economy under the name of cheapness, true economy be embraced, the trench in which a pipe drain is to be laid will be dug out from six to twelve inches deeper than is required for the drain, and a layer of concrete of that thickness, and of the full breadth of the trench, placed in it, and formed with the full required for the inside of the drain. This can be done under the eye, and will be open to the correction, of the supervisor, as in building a brick-drain; and the pipes may be laid, and the joints formed, upon the firm and evenly laid concrete with truth and certainty, even though the joints be socketted. Concrete being filled in under and about the pipes when so laid, up to half the diameter of the round body, the ground may be filled over the drain, with confidence that it will possess the great requisites of truth and strength, with the peculiar excellence which the pipe possesses of smoothness of surface in the run of the drain. A pipe drain so laid will not be cheaper than a drain of the same size of brickwork; but it will be strong against everything short of crushing pressure. Light weight is crushing pressure to pot-pipes, however, and pipes of pottery may not, therefore, be laid under carriage roads, nor anywhere else, indeed, of such large size as to break under any dead weight that can come upon them, or under any impact to which they may be exposed. The strength of the strongest pottery pipes is, nevertheless, but weakness as compared with the thinnest brickwork in tubular drains.

In fine, with careful workmanship and a good foundation, either brick and mortar, or sheet-iron collared pipes, will make a good, lasting, and serviceable drain; whilst with careless or bad workmanship, and an infirm bed, a brick drain may be bad, but a pipe drain under the same circumstances must be so.

But the best built and best laid and jointed sewers and drains, of whatever materials or however put together, and with the best outfall, are but the means by which the material parts of cloacal and other foul refuse in a liquid state are made to pass away; the immaterial parts are not thereby ejected. The hot waste-water of the scullery helps, by diluting it, to hurry on the more sluggish matters which enter the same drain from the cloaca; but the heat in the culinary waste not only throws off in a gaseous form, and often enveloped in steam, the sickening odour which the water has taken out of the esculents boiled in it, but it induces the evolution of faint but foul gases from the cloacal filth itself, and these rise and run back to the highest attainable level, and seek egress into the upper air. This is commonly obtained through some faulty sink, or by crannies in the drain within the house from which the matters had proceeded, the escape being aided powerfully by the kitchen, and in winter time by the focal fires; and in the streets of sewered towns the reeking stench rises through gully gratings; or if these are effectually trapped, then through holes made for the purpose in the carriage-roadway, where, however, they are very commonly clogged up with road stuff, which now and then drops down into the sewer, and forms an obstruction to the turbid stream there. By some or other of these vents, however, the stench escapes from drains and sewers, rises and mingles with the air, to be again inhaled by human beings. And thus it is that the air is circulated and the sewers ventilated in our best sewered towns!

Now, the course proper to be pursued is almost the reverse of that commonly practised, from which the inhabitants of sewered towns suffer in comfort and in health, more perhaps than the inhabitants of unsewered towns, in which there is commonly no such concentration of foulnesses. Give freedom to the foul gases of the drains, as freedom is given to the air which has served the purposes of combustion in the

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1 The best expedient known to the present writer is one recently patented by Mr Jennings, a London manufacturer. Mr Jennings makes the pipes simple hollow cylinders, and lays their ends upon half-round chairs, and covers the joint with a half-round saddle which completes the circuit. The chair and saddle are both related, and form together a short length of pipe. Much depends upon the strength and soundness of the chair; but these qualities being secured, the joints may be made upon them in mortar with confidence. This is better than the sheet-iron collar which the writer has heretofore advocated. chimney-grate. Make a flue for the foul air of the drain of every house, at or near to its upper end, as a flue is made for the escape of the burnt air of the smokeless coke or charcoal fire, as well as for the combined burnt air and dirty, but harmless, smoke of the coal fire to pass off by, and both will alike rise into the upper air, to be dissipated by the winds of heaven and prepared by nature's chemistry to reappear as the course of nature prescribes.

A lofty shaft built at the head of every main line of sewer, and provided with the means of securing an up-draught through the shaft—means to which the wind will always give effect in even the stiffest weather—would give vent to all the emanations which arise in the sewer itself; but to assure this result there must be no trapping or flapping of the inlets to the sewer—the air must be allowed to pass down freely, which it will do, firstly, by its own gravity, and, secondly, by the draught established in the sewer by the upper draughting shaft and by the house drain flues. But the mechanical details involved in the practice of drainage is matter for technical and professional consideration.

The frequent and careful removal of all dirt and filth from the surfaces of the streets by scavengering—the constant flow to an efficient outfall in subdrains of all liquid waste and foul matters soluble in water, and rendered fluid by a copious backwater, may make and keep a town clean; but neither a town as a whole, nor any place in a town,—be it palace or cottage,—can be sweet and wholesome unless the drains and sewers are swept by constant currents of air, or, in other words, thoroughly ventilated from the lower into the upper air.—The metropolis of the British empire, the home of the Sovereign, the seat of the Legislature, the place of birth and the constant residence of more than a million and a half of human beings who consider themselves high in the scale of civilization, is but indifferently scavengered, is drained and sewered upon a wholly defective system, and its drains and sewers reek with filth and pour out under our nostrils foul air for want of legitimate outfalls for the one, and elevated outlets for the other.1

AGRICULTURAL DRAINAGE.

To drain land is to rid it of its superfluous moisture. The rivers of a country with their tributary brooks and rills are the natural provision for removing the rain water which either flows directly from its surface, or which, after percolating through porous strata to an indefinite depth, is again discharged at the surface by springs. The latter may thus be regarded as the outlets of a natural underground drainage. This provision for disposing of the water that falls from the clouds is usually so irregular in its distribution, and so imperfect in its operation, that it leaves much to be accomplished by human labour and ingenuity. The art of the drainer accordingly consists—

1st, In improving the natural outfalls by deepening, straightening, or embanking rivers; and by supplementing these, when necessary, by artificial canals and ditches; and,

2d, In freeing the soil and subsoil from stagnant water, by means of artificial underground channel.

The first of these operations, called trunk drainage, is the most needful; for until it be accomplished there are extensive tracts of land, and that usually of the most valuable kind, to which the secondary process either cannot be applied at all, or only with the most partial and inefficient results. Very many of our British rivers and streams flow with a sluggish and tortuous course through valleys of flat alluvial soil, which, as the coast is approached, expand into extensive plains, but little elevated above the level of the sea. Here the course of the river is obstructed by shifting shoals and sand banks, and by the periodic influx of the tides. The consequence is, that immense tracts of valuable land are at all times in a water-logged and comparatively worthless state, and on every recurrence of a flood are laid entirely under water. In a preceding volume (see Agriculture) some account has already been given of the extent of this evil, and of the efforts that have been successfully devoted to its remedy. Some of these fen-lands and estuary drainage works have been accomplished in the face of natural obstacles of the most formidable character, and constitute trophies of engineering talent of which the country may well be proud. Great as the natural difficulties are which have to be encountered in such cases, there are others of a different kind which have often proved more impracticable. It has been found easier to exclude the sea and restrain land-floods, than to overcome the prejudices and reconcile the conflicting interests of navigation companies, commissioners of sewers, owners of mills, and landed proprietors. Although all these classes suffer the most serious losses and inconveniences from the defective state of many of our rivers, yet it is found extremely difficult to reconcile their conflicting claims, and to allocate to each their proper share of the cost of improvements by which all are to benefit. A most interesting and instructive illustration of the urgent necessity for improving the state of our rivers, of the difficulties to be encountered in doing so, and of the incalculable benefits thus to be obtained, has been published in an essay on Trunk Drainage by John Algernon Clarke, Esq., published in vol. xv., part 1st, of the Journal of the Royal Agricultural Society of England. Mr Clarke, after some most important observations on trunk drainage, describes in detail works projected under powers granted in an act of parliament, passed in 1852, "constituting commissioners for the improvement of the river Nene and the navigation thereof."

There is not a district of the kingdom in which works similar in kind are not absolutely indispensable, before extensive tracts of valuable land can be rendered available for profitable cultivation by means of underground drainage. It is interesting to know that the necessity for trunk drainage, and the means of accomplishing it, were distinctly set before the public 200 years ago by a practical draining engineer, to whose writings the attention of the agricultural community has been frequently directed of late by Messrs Parkes, Gisborne, and others. From the third edition (1652) of The Improver Improved, by Walter Blithe, the author referred to, in which the true principles of land drainage are stated as distinctly, and urged as earnestly, as by any of our modern writers, we here quote the following remarks:

"A strait watercourse, cut a considerable depth, in a thousand parts of this nation, would be more advantageous than we are aware of, or I will task myself here to dispute further. And though many persons are interested therein, and some will agree, and others will oppose; one creek lyeth on one side of the river, in one lord's manor, and another lyeth on the other side, and divers men own the same; why may not one neighbour change with another, when both are gainers? If not, why may they not be compelled for their own good, and the common good of the nation, to exchange? Many acres of very rich land may hereby be gained, and possibly as many more much amended, that are almost destroyed; for a law is wanting herein for the present, which I hope will be supplied if it may appear advancement to the public; for to private interests it is not possible to be the least prejudice, when every man hath benefit, and each man may also have an equal allowance if the least prejudiced.

"But a word or two more, and so shall conclude this chapter—and

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1 This is not the first time that the writer of this article has called attention to the means above indicated of ventilating house drains and common sewers respectively. In evidence before the State of Large Towns Commission in 1843, in his joint report under the preliminary inquiries Act in 1847—in his "Guide to the proper Regulation of Buildings in Towns, otherwise Healthy Houses," in 1848-49—and in his place as a Metropolitan Commissioner of Sewers in 1852-53, he has earnestly urged the necessity of ventilation as applied to drains and sewers, and pointed out the means above indicated of effecting it. It is a little to further this improvement through a great destruction (as some may say); it is the removing or destroying of all such mills, and none else, as drown and corrupt more lands than themselves are worth to the commonwealth, and they are such as are kept up or damned so high as that they boggyfie all the lands that lie under their mill-head. Such mills as are of little worth, or are by necessity great clogs, maintained only by pulled down; the advance of the land, when the water is let run back course, and not impounded, will be of far greater value many times. But in case the mills should be so necessary and profitable too, and far more than the lands they spoil, I shall then advise, that under thy mill-dam, so many yards wide from it as may prevent breaking through, thou make a very deep trench all along so far as thy lands are putrefied, and thereinto receive all the issuing, spewing water, and thereby stop or cut off the feeding of it upon thy meadow, and carry it away back into thy back-water or false course, by as deep a trench, cut through the most low and convenient part of thy meadow, and so carry it back into thy back-water or false course; on that side thy mill-dam, then thou must make some course, or plant some trough under thy mill-dam, and so carry it under into some lower course that may preserve it from soaking thy meadows or pastures under it; and by this means thou must in a good measure reduce thy land to good soundness, and probably wholly cure it, and preserve thy mill also.

It is painful to reflect, that after the lapse of two centuries, we should still see, as Blithe did, much "gallant land" ruined for want of those draining operations which he so happily describes.

A clear outfall of sufficient depth being secured, the way is open for the application of underground draining. And here it may be proper to state, that there is very little of the land of Great Britain naturally so dry as not to be susceptible of improvement by artificial draining; for land is not in a perfect condition with respect to drainage, unless all the rain that falls upon it can sink down to the minimum depth required for the healthy development of the roots of cultivated crops, and thence find vent, either through a naturally porous subsoil or by artificial channels. Much controversy has taken place as to what this minimum depth is. Suffice it to say, that opinion is now decidedly in favour of a greater depth than was considered necessary even a few years ago, and that the best authorities concur in stating it at from three to four feet. There are persons who doubt whether the roots of our ordinary grain or green crops ever penetrate to such a depth as has now been specified. A careful examination will satisfy any one who makes it that minute filamentary rootlets are sent down to extraordinary depths, wherever they are not arrested by stagnant water. It has also been questioned whether any benefit accrues to crops from this deep descent of their roots. Some persons have even asserted that it is only when they do not find food near at hand that they thus wander. But it must be borne in mind that plants obtain moisture as well as nourishment by means of their roots, and the fact is well known that plants growing in a deep soil resting on a porous subsoil seldom or never suffer from drought. It is instructive, too, on this point, to observe the practice of the most skilful gardeners, and see the importance which they attach to trenching, the great depth at which they often deposit manure, and the stress which they lay upon thorough drainage. On the other hand, it is well known that soils which soonest become saturated, and run from the surface in wet weather, are precisely those which parch and get chapped the soonest in drought. The effectual way to secure our crops at once from drowning and parching, is to put the land in a right condition with respect to drainage.

All soils possess more or less the power of absorbing and retaining water. Pure clays have it in the greatest degree, and gritty siliceous ones in the smallest. In dry weather this power of attracting moisture is constantly operating to supply from below the loss taking place by evaporation at the surface. In heavy rains, as soon as the entire mass has drunk its fill, the excess begins to flow off below; and therefore a deep stratum, through which water can percolate, but in which it can never stagnate—that is, never exceed the point of saturation—is precisely that in which plants are most secure from the extremes of drought and drowning.

If a perfect condition of the soil with respect to drainage is of importance for its influence in preserving it in a right condition as respects moisture, it is still more so for its effects upon its temperature. All who are conversant with rural affairs are familiar with that popular classification of soils in virtue of which such as are naturally dry are also invariably spoken of as warm and early; and conversely, that wet soils are invariably described as being cold and late. This classification is strictly accurate, and the explanation of it is simple. An excess of water in soil keeps down its temperature in various ways. In passing into the state of vapour it rapidly carries off the heat which the soil has obtained from the sun's rays. Water possesses also a high radiating power; so that, when present in the soil in excess, and in a stagnant state, it is constantly carrying off heat by evaporation and radiation. On the other hand, stagnant water conveys no heat downwards; for, although the surface is warmed, the portion of water thus heated being lightest, remains floating on the surface, and will give back its heat rapidly to the atmosphere, but conveys none downwards. When the surface of stagnant water becomes colder than the general mass, the very opposite effect immediately ensues; for as water cools its density increases, and thus causes an instant sinking of the portion that has been cooled, and a rising of a warm portion from below to take its place—this movement continuing until the whole has been lowered to 42°, at which point water reaches its maximum density, after which it will freeze at the surface if the cold be great enough. It is thus that soil surcharged with water is kept at a lower temperature than similar soil that has a sufficient natural or artificial drainage.

But while the presence of stagnant water in a soil has this injurious power of lowering its temperature, a very different effect ensues when rain-water can sink freely into it to a depth of several feet, and then find a ready exit by drainage; for in this case the rain-water carries down with it the heat which it has acquired from the atmosphere and from the sun-heated surface, and imparts it to the subsoil. There is as yet a lack of published experiments to show the ordinary increase of temperature at various depths and in different soils, as the result of draining wet land. Those conducted by Mr Parkes, in a Lancashire bog in June 1837, showed, as the mean of 35 observations, that the drained and cultivated soil at 7 inches from the surface was 10° warmer than the adjoining undrained bog in its natural state at the same depth. It is understood that recent experiments conducted by the same gentleman on an extended scale fully establish the fact that an increased temperature of the soil is an unfailing accompaniment of thorough draining. The importance of this result cannot well be overrated. The temperature and other conditions of the atmosphere, which we call climate, are placed beyond human control; but this power of raising the temperature of all wet, and consequently cold soils, becomes tantamount in some of its results to a power of improving the climate. There are, accordingly, good grounds for stating that in numerous cases grain crops have ripened sooner by 10 or 12 days than they would have done but for the draining of the land on which they grew.

The points which we have thus briefly touched upon are so essential to an intelligent appreciation of the subject, that we have felt constrained to notice them, however meagrely. But our space forbids more than a mere enumeration of some of the many evils inseparable from the presence of stagnant water in the soil, and of the benefits that flow from its removal. Wet land, if in grass, produces only the coarser grasses, and many sub-aquatic plants and mosses, which are of little or no value for pasturage; its herbage is late of coming in spring, and fails early in autumn; the animals grazed upon it are unduly liable to disease, and sheep, especially, to the fatal rot. When used as arable land, tillage operations are easily interrupted by rain, and the period always much limited in which they can be prosecuted at all; the compactness and toughness of such land renders each operation more arduous, and more of them necessary than in the case of dry land. The surface must necessarily be thrown into ridges, and the furrows and cross-cuts duly cleared out after each process of tillage, on which surface expedients as much labour has probably been expended in each thirty years, as would now suffice to make drains enough to lay it permanently dry. With all these precautions, the best seed-time is often missed, and this usually proves the prelude to a scanty crop, or to a late and disastrous harvest.

The cultivation of the turnip and other root crops, which require the soil to be brought to a deep and free tilth, becomes either altogether impracticable, and must be abandoned for the safe but costly bare fallow, or is carried out with great labour and hazard; and the crop, when grown, can neither be removed from the ground, nor consumed upon it by sheep without damage by poaching. The dung, lime, and other manure, that is applied to such land, is in a great measure wasted; and the breaking of the subsoil and general deep tillage, so beneficial in other circumstances, is here positively mischievous, as it does but increase its power of retaining water. Taking into account the excessive labour, cost, and risk, inseparable from the cultivation of wet land, and the scanty and precarious character of the crops so obtained, it would in many cases be wiser to keep such lands in grass, than to prosecute arable husbandry under such adverse circumstances. These very serious evils can either be entirely removed, or, at the least, very greatly palliated by thorough draining. It often happens that naturally porous soils are so soaked by springs, or so water-logged by resting upon an impervious subsoil, or, it may be, so drowned for want of an outfall in some neighbouring river or stream, that draining at once effects a perfect cure, and places them on a par with the best naturally dry soils. In the case of clay soils, the improvement effected by draining is in some respects greater than in any other class, but still it cannot change the inherent properties of clay. This has sometimes been overlooked by sanguine improvers, who, hastily assuming that their strong land, when drained, would henceforward be as friable and sound as the more porous kinds, have proceeded to treat it on this assumption, and have found to their cost that clay, however well drained, will still get into mortar and clods, if it is tilled or trodden too soon after rain. It is entirely owing to such rash and unskilful management that an opinion has sometimes got abroad that clay lands are injured by draining. They merely retain the qualities peculiar to clay; and when they are treated judiciously, show as good a comparative benefit from draining as other soils. The only instances in which even temporary injury arises from draining is in the case of some peaty and fen lands, which are so loose, that they suffer from drought in protracted dry weather. As such lands are usually level and have water-courses near them, this inconvenience admits of an easy remedy by shutting up the main outlets and then admitting water into the ditches. The drains in this way become ready channels for applying the needed moisture by a kind of subterraneous irrigation.

The beneficial effects of thorough draining are of a very decisive and striking kind. The removal of stagnant water from a stratum of 4 feet in depth, and the establishing of a free passage for rain-water and air from the surface to the level of the drains, speedily effects most important changes in the condition of the soil and subsoil. Ploughing and other tillage operations are performed more easily than heretofore, in consequence of a more friable state of the soil.

Moderate rains which formerly would have sufficed to arrest these operations do no longer, and heavy falls of rain cause a much shorter interruption of these labours than they did when the land was in its natural state. Deep tillage, whether by the common or subsoil plough (which formerly did harm), now aids the drainage, and is every way beneficial. Ridges and surface furrows being no longer needed, the land can be kept flat with great benefit to crops, and furtherance to field operations. An earlier seed-time and harvest, better crops, a healthier live stock, and an improved style of husbandry, are the usual and well known sequents of judiciously conducted drainage operations. In short, the most experienced and skilful agriculturists now declare with one consent that good drainage is an indispensable preliminary to good cultivation.

Although it has been reserved to the present times to Antiquity see land draining reduced to a system based on scientific principles, or very great improvement effected in its details, it is by no means a modern discovery. The Romans were careful to keep their arable lands dry by means of open trenches, and there are even some grounds for surmising that they used covered drains for the same purpose. Indubitable proof exists that they constructed underground channels by means of tubes of burned earthenware; but it seems more probable that these were designed to carry water to their dwellings, &c., than that they were used simply as drains. Recent inquiries and discoveries have also shown that it is at least several centuries since covered channels of various kinds were in use by British husbandmen for drying their land. It is, at all events, two centuries since Capt. Walter Blithe wrote as follows:

"Superfuous and venomous water, which lyeth in the Blithe's earth and much occasioneth bogginesse, miriness, rushes, trentles, flags, and other filth, is indeed the chief cause of barrenesse in any land of this nature. Draying is an excellent and chiefest means for their reducement; and for the depth of such draynes, I cannot possibly bound, because I have not time and opportunity to take in all circumstances. And for thy drayning trench it must be made so deepe that it goe to the botomme of the cold, spewing moist water, that feeds the flagg and the rush; for the widenesse of it, use thine owne liberty, but be sure to make it so wide as thou mayest goe to the botomme of it, which must be so low as any moisture lyeth, which moisture usually lyeth under the over and second swarth of the earth, in some gravel or sand, or else, where some greater stones are mixt with clay, under which thou must goe halfe one spades graft deepe at least; yea, suppose this corruption that feeds and nourisheth the rush or flagg should lie a yard or foure foot deepe, to the botomme of it thou must goe, if ever thou wilt drain it to purpose. And for the drayning trench be sure thou indavour to carry it as neare upon a straight line as possible. To the botomme where the spewing spring lyeth thou must goe, and one spades depth or graft beneath, how deep so ever it be, if thou wilt drayne thy land to purpose. I am forced to use repetitions of some things, because of the suitableness of the things to which they are applied; as also because of the slownesse of peoples apprehensions of them, as appears by the non-practice of them, the which wherever you see drayning and trenching you shall rarely find few or none of them wrought to the botomme. Go to the botomme of the bog, and there make a trench in the sound ground, or else in some old ditch, so low as thou verily conceivest thy self assuredly under the level of the spring or spewing water, and then carry up thy trench into thy bogg straight through the middle of it, one foot under that spring; but for these common and many trenches, oft times crooked too, that men usually make in their bogggy grounds, some one foot, some two, never having respect to the cause or matter that maketh the bogg to take that way, I say away..." with them as a great piece of folly, lost labour, and spoyle. After thou hast brought a trench to the bottom of the bog; then cut a good substantial trench about thy bog; and when thou hast so done make one work or two just overthwart it, upwards and downwards, all under the matter of the bog. Then thou must take good green faggots, willow, alder, elm, or thorne, and lay in the botome of thy works, and then take thy turf thou tookest up in the top of thy trench, and plant upon them with the green sward downwards; or take great pebbles, stones, or flint stones, and so fill up the botome of thy trench about fifteen inches high, and take thy turf and plant it as aforesaid, being cut very fit for the trench, as it may join close as it is laid down, and then having covered it all over with earth, and made it even as thy other ground, wait and expect a wonderfull effect through the blessing of God."

These sagacious arguments and instructions were doubtless acted upon by some persons in his own times and since; but still they had never attained to general adoption, and were ultimately forgotten. Towards the close of last century, Mr Elkington, a Warwickshire farmer, discovered and promulgated a plan of laying dry sloping land that is drowned by the outbursting of springs. When the higher lying portion of such land is porous, rain falling upon it sinks down until it is arrested by clay or other impervious matter, which causes it again to issue at the surface and wet the lower-lying ground. Elkington showed that by cutting a deep drain through the clay, aided when necessary by wells or augur holes, the subjacent bed of sand or gravel in which a body of water is pent up by the clay, as in a vessel, might be tapped, and the water conveyed harmlessly in the covered drain to the nearest ditch or stream. In the circumstances to which it is applicable, and in the hands of skilful drainers, Elkington's plan, by bringing into play the natural drainage furnished by porous strata, is often eminently successful. His system was given to the public in a quarto volume, edited by a Mr John Johnston of Edinburgh, who does not seem to have shared the engineering talents of the man whose discoveries he professes to expound.

During the thirty or forty years subsequent to the publication of this volume, most of the draining that took place was on this system, and an immense capital was expended in such works with very varying results. Things continued in this position until about the year 1823, when the late James Smith of Deanston having discovered anew those principles of draining so long before indicated by Blithe, proceeded to exemplify them in his own practice, and to expound them to the public in a way that speedily effected a complete revolution in the art of draining, and marked an era in our agricultural progress. Instead of persisting in fruitless attempts to dry extensive areas by a few dexterous cuts, he insisted on the necessity of providing every field that needed draining at all with a complete system of parallel underground channels, running in the line of the greatest slope of the ground, and so near to each other that the whole rain falling at any time upon the surface should sink down and be carried off by the drains. The distances between drains he showed must be regulated by the greater or less retentiveness of the ground operated upon, and gave 10 feet as the minimum, and 40 feet as the maximum of these distances. The depth which he prescribed for his parallel drains was 30 inches, and these were to be filled with 12 inches of stones small enough to pass through a 3-inch ring—in short, a new edition of Blithe's drain. A main receiving-drain was to be carried along the lowest part of the ground with sub-drains in every subordinate hollow that the ground presented. These receiving-drains were directed to be formed with a culvert of stone work, or of tiles, of waterway sufficient to contain the greatest volume of water at any time requiring to be passed from the area to which they respectively supplied the outlet. The whole cultivated lands of Britain being disposed in ridges which usually lie in the line of greatest ascent, it became customary to form the drains in each furrow, or in each alternate, or third, or fourth one, as the case might require, or views of economy dictate, and hence the system soon came to be popularly called furrow draining. From the number and arrangement of the drains, the terms frequent and parallel were also applied to it. Mr Smith himself more appropriately named it, from its effects, thorough draining. The sound principles thus promulgated by him were speedily adopted and extensively carried into practice. The great labour and cost incurred in procuring stones in adequate quantities, and the difficulty of carting them in wet seasons, soon led to the substitution of tiles and soles of burned earthenware. The limited supply and high price of these tiles for a time impeded the progress of the new system of draining; but the opportune invention by the Marquis of Tweeddale of a tile-making machine, followed as this was by a rapid succession of more perfect machines for the same purpose, at once removed this impediment, and gave a mighty stimulus to this fundamental agricultural improvement. The substitution of cylindrical pipes for the original horse-shoe tiles has still further aided the progress of land-drainage, both by lowering the cost and increasing the efficiency and permanency of such works.

The system introduced and so ably expounded by Smith of Deanston has now virtually been adopted by all drainers. Variations in matters of detail (having respect chiefly to the depth and distance apart of the parallel drains) have indeed been introduced; but the distinctive features of his system (viz., provision for laying dry the entire area of land operated upon to the minimum depth required for the healthy growth of cultivated crops, by a series of parallel drains running in the line of the greatest slope of the ground) are now recognised and acted upon by all scientific drainers.

In setting about the draining of a field, or farm, or estate, Direction the first point is to secure, at whatever cost, a proper outfall, or drains. The lines of the receiving drains must next be determined, and then the direction of the parallel drains. The former must occupy the lowest part of the natural hollows, and the latter must run in the line of the greatest ascent of the ground. In the case of flat land, where a fall is obtained chiefly by increasing the depth of the drains at their lower ends, these lines may be disposed in any direction that is found convenient; but in undulating ground a single field may require several distinct sets of drains lying at different angles, so as to suit its several slopes. When a field is ridged in the line of the greatest ascent of the ground, there is an obvious convenience in adopting the furrows as the site of the drains; but wherever this is not the case the drains must be laid off to suit the contour of the ground, irrespective of the furrows altogether. When parts of a field are flat and other parts have a considerable acclivity, it is expedient to cut a receiving drain near to the bottom of the slopes, and to give the flat ground an independent set of drains. In laying off receiving drains it is essential to give hedge-rows and trees a good offing, lest the conduit should be obstructed by roots. When a main drain is so placed that parallel ones empty into it from both sides, care should be taken that the inlets of the latter are not made exactly opposite to each other. Indeed, we have found it expedient in such cases to have two receiving drains parallel to each other, each to receive the subordinate drains from its own side only. As these receiving drains act also as ordinary drains to the land through which they pass, no additional cost is incurred by having two instead of one, provided they are as far apart as the other drains in the field. Much of the success of draining depends on the skilful planning of these main drains, and in making them large enough to discharge the greatest flow of water to which they may be exposed. Very long main drains are to be avoided. Na-

Numerous outlets are also objectionable, from their liability to obstruction. An outlet to an area of from ten to fifteen acres is a good arrangement. These outlets should be faced with mason-work, and guarded by iron gratings.

The depths of the parallel drains must next be determined. In order to obtain proper data for doing so, the subsoil must be carefully examined by digging test-holes in various places, and also by taking advantage of any quarries, deep ditches, or other cuttings in the proximity, that afford a good section of the ground. We have already expressed an opinion that the drains should not be less than four feet deep; but it is quite possible that the discovery at a greater depth than four feet of a seam of gravel, or other very porous material charged with water, underlying considerable portions of the ground, may render it expedient to carry the drains so deep as to reach this seam. Such a seam, when furnished with sufficient outlets, supplies a natural drain to the whole area under which it extends. When such exceptional cases are met with, they are precisely those in which deep drains, at wide intervals, can be trusted to dry the whole area. When the subsoil consists of a tenacious clay of considerable depth, it is considered by many persons that a greater depth than three feet is unnecessary. The greater depth is, however, always to be preferred; for a drain of four feet, if it works at all, not only does all that a shallower one can do, but frees from stagnant water a body of subsoil on which the other has no effect at all. It has indeed been alleged that such deep drains may get so closed over by the clay that water will stand above them. If the surface of clay soil is wrought into puddle by improper usage, water can undoubtedly be made to stand for a time over the shallowest drains as easily as over the deepest. But the contraction which takes place in summer in good alluvial clays gradually establishes fissures, by which water reaches the drains. In such soils it is usually a few years before the full effect of draining is attained. This is chiefly due to the contraction and consequent cracking of clay soils in summer just referred to, and partly, as Mr Parkes thinks, to the mining operations of the common earth-worm. Both of these natural aids to drainage operate with greater force with drains 4 feet deep than when they are shallower. The tardy percolation of water through clay soils seems also a reason why in such cases it should get the benefit of a greater fall, by making the drain deep. Draining is always a costly operation, and it is therefore peculiarly needful to have it executed in such a way that it shall be effectual and permanent. We advocate a minimum depth of 4 feet, because of our strong conviction that such drains carefully made will be found to have both these qualities. And this opinion is the result of dear-bought experience, for we have found it necessary in our own case to re-open a very considerable extent of 30-inch drains in consequence of their having totally failed to lay the land dry, and to replace them by 4-feet ones, which have proved perfectly efficacious. In doing this we have seen a 30-inch drain opened up and found to be perfectly dry, and yet when the same trench was deepened to 4 feet there was quite a run of water from it. We earnestly dissuade all parties who are about to undertake drainage works from giving ear to representations about the sufficiency and economy of shallow drains. These, doubtless, cost somewhat less to begin with, but in thousands of cases they fail to accomplish the desired end, and the unfortunate owners, after all their outlay, are left to the miserable alternative of seeing their land imperfectly drained, or of executing the works anew, and thus losing the whole cost of the first and inefficient ones. The extreme reluctance with which the latter alternative is necessarily regarded will undoubtedly operate for a long time in keeping much land that has been hastily and imperfectly drained from participating in the benefits of thorough drainage. The distance apart at which the drains should be cut must be determined by the nature of the subsoil. In the most retentive clays it need not be less than 18 feet. On the other hand, this distance cannot safely be exceeded in the case of any subsoil in which clay predominates, although it should not be of the most retentive kind. In all parts of the country instances abound in which drains cut in such subsoils, from 24 to 30 feet apart, have totally failed to lay the land dry. When ground is once pre-occupied by drains too far apart, there is no remedy but to form a supplementary one betwixt each pair of the first set; and thus, by exceeding the proper width at first, the space betwixt the drains is unavoidably reduced to 12 or 15 feet, although 18 feet would originally have sufficed. It is only with a decided porosity in the subsoil, and in proportion to the degree of that porosity, that the space betwixt drains can safely be increased to 24, or 30, or 36 feet. In those exceptional cases in which drains more than 36 feet apart prove effectual, their success is due to the principle on which Elkington's system is founded. A few years ago an opinion obtained currency, that as the depth of drains was increased their width apart might with safety be increased in a corresponding ratio. And hence it came to be confidently asserted, that with a depth of 5 or 6 feet a width of from 40 to 60 feet might be adopted with a certainty of success, even in the case of retentive soils. We believe that experience has already demonstrated the unsoundness of this opinion. At all events, in recommending a minimum depth of 4 feet, we do so on the ground that (other things being equal) the whole benefits of drainage are more fully and certainly secured by drains of this depth than by those of 2½ or 3 feet. In ordinary cases an increase of depth does not compensate for an increase of the width apart of the drains.

Cylindrical pipes with collars are undoubtedly the best pipes and draining material that has yet been discovered. The collars referred to are simply short pieces of pipe, just so wide in the bore as to admit of the smaller pipes which form the drain passing freely through them. In use, one of these collars is so placed as to encase the ends of each contiguous pair of tubes, and thus forms a loose fillet around each jointing. The ends of these pipes being by this means securely kept in contact, a continuous canal for the free passage of water is infallibly insured; the jointings are guarded against the entrance of mud or vermin, and yet sufficient space is left for the admission of water. Pipes of all diameters, from 1 inch to 16 inches, are now to be had; those from 1 to 2 inches in the bore are used for subordinate drains; the larger sizes for sub-main and main receiving drains. Collars are used with the smaller sizes only, large pipes not being so liable to shift their position as small ones. In constructing a drain it is of much importance that the bottom be cut out just wide enough to admit the pipes and no more. Pipes, when thus accurately fitted in, are much less liable to derangement than when laid in the bottom of a trench several times their width, and into which a mass of loose earth must necessarily be returned. This accurate fitting is now quite practicable in the case of soils tolerably free from stones from the excellence of the draining tools that have lately been introduced. The following cut represents the most important of these tools.

c and e are long tapering spades for digging out the middle and bottom splits, If a quicksand is encountered in constructing a drain, it will be found expedient to put a layer of straw in the bottom of the trench, and then, instead of the ordinary pipe and collar, to use at such a place a double set of pipes—one within the other—taking care that the joinings of the inner set are covered by the centres of the outer ones. By such precautions the water gets vent, and the running sand is excluded from the drain. When a brook has been diverted from its natural course for mill-power or irrigating purposes, it often happens that portions of land are thereby deprived of the outfall required to admit of their being drained to a proper depth. In such cases it is frequently practicable to obtain the needed outlet by carrying a main drain through below the water-course, by using at that point a few yards of cast-iron pipe, and carefully filling up the trench with clay puddle, so that there may be no leakage from the water-course into the drain. While this is doing

| Intervals between the Drains in feet | Rods per acre | Twenty-one inches Pipes, each Pipe, inch Pipes | |-------------------------------------|--------------|-----------------------------------------------| | | | Thirteen-inch Pipes, each Pipe, inch Pipes | | | | Fourteen-inch Pipes, each Pipe, inch Pipes | | | | Fifteen-inch Pipes, each Pipe, inch Pipes | | 18 | 1461 | 2420 | | 21 | 1255 | 2074 | | 24 | 110 | 1815 | | 27 | 97 | 1613 | | 30 | 88 | 1452 |

Table II.—Showing the Cost of Draining per acre at different intervals between the Drains.

| Labour, cutting and filling in at 6d. per rod | Material, pipes for minor drains, 18s. per 1000 | Haulage, two miles, and delivery in fields at 2s. 6d. per 1000 | Pipe-laying and finishing, 1d. per rod | Superintendent, foreman | Extra for mains | Iron-outlet pipes, and masonry, and extra labour | Total | Add for collars, if used | |------------------------------------------------|--------------------------------------------------|-------------------------------------------------------------|----------------------------------------|-----------------------|---------------|-------------------------------------------------|-------|------------------------| | L s. d. | L s. d. | L s. d. | L s. d. | L s. d. | L s. d. | L s. d. | L s. d.| L s. d. | | 3 13 4 | 3 2 10 | 2 15 0 | 2 8 11 | 2 4 0 | | | | | | 2 5 9 | 1 19 | 1 14 3 | 1 10 6 | 1 7 5 | | | | | | 0 6 4 | 0 5 5 | 0 4 9 | 0 4 3 | 0 3 9 | | | | | | 0 12 2 | 0 10 | 0 9 2 | 0 8 2 | 0 7 4 | | | | | | 0 5 0 | 0 5 0 | 0 5 0 | 0 5 0 | 0 5 0 | | | | | | 0 1 0 | 0 2 0 | 0 2 0 | 0 2 0 | 0 2 0 | | | | | | 0 1 6 | 0 1 6 | 0 1 6 | 0 1 6 | 0 1 6 | | | | | | 7 6 1 | 6 6 5 | 5 11 8 | 5 0 4 | 4 11 0 | | | | | | 1 2 10 | 0 19 | 0 17 1 | 0 15 3 | 0 13 8 | | | | |

Various attempts have from time to time been made to lower the cost of draining land by the direct application of animal or steam power to the work of excavation. The most successful of these attempts is the steam-draining apparatus invented by Mr John Fowler of Bristol, usually called Fowler's draining plough. A six-horse portable steam-engine is anchored in one corner of the field to be drained. It gives motion to two drums, to each of which a rope, 500 yards long, is attached, the one uncoiling as the other is wound up. These ropes pass round blocks which are anchored at each end of the intended line of drain, and are attached one to the front and the other to the hind end of the draining apparatus. This consists of a framework, in which is fixed, at any required depth not exceeding 3½ feet, a strong coulter terminating in a short horizontal bar of cylindrical iron, with a piece of rope attached to it, on which a convenient number of drain pipes are strung. This frame being pulled along by the engine, the coulter is forced through the soil at a regulated depth, and deposits its string of pipes with unerring accuracy, thus forming, as it proceeds, a perfect drain. The supply of pipes is kept up by means of holes previously dug in the line of the drain, at distances corresponding to the length of the rope on which they are strung. This machine was subjected to a very thorough trial at the meeting of the Royal Agricultural Society of England, at Lincoln, in 1854, on which occasion a silver medal and very high commendation were awarded to it. In March 1855 it was publicly stated that five of these implements are now at work in different parts of England, and that already 10,000 acres of land have been drained by means of them. At the Lincoln trial it was satisfactorily proved that this implement could work at a depth of 3½ feet. As it moved along, the soil on either side, to the width of 2 or 3 feet, seemed to be loosened. It is therefore probable that this implement, or at least one propelled on the same principle, may yet be used as a subsoil disintegrator.

A great stimulus has recently been given to the improvement of land by the passing of a series of acts of parliament, draining which have removed certain obstacles which effectually hindered the investment of capital in works of drainage and kindred ameliorations. By the first of these acts, passed in 1846, a sum of £4,000,000 of the public money was authorized to be advanced to landowners to be expended in draining their lands. The Inclosure Commissioners were charged with the allocation of this money, and the superintendence of its outlay. The most important provisions of this act are, that it enables the possessors of entailed estates (equally with others) to share in the benefits of this fund—that it provides, on terms very favourable to the borrower, for the repayment of the money so advanced by twenty-two annual instalments—that before sanctioning the expenditure of these funds on drainage works, the commissioners must have a report from a qualified inspector, to the effect that they are likely to prove remunerative—and finally, that the works must be performed according to specifications prepared by the inspector, and approved by the commissioners, who have seldom allowed of a less depth of drain than $3\frac{1}{2}$ feet. By the end of the year 1854 the whole of this money was allocated, and more than half of it actually expended. Scottish landowners were so prompt to discern, and so eager to avail themselves of this public fund, that more than half of it fell to their share. The great success of this measure, and the rapid absorption of the fund provided by it soon led to further legislative acts, by which private capital has been rendered available for the improvement of land, by draining and otherwise, on conditions similar to those just enumerated.

These acts are—

1st, The Private Money's Drainage Act (12th and 13th Vict., cap. 100), limited to draining only.

2d, The West of England, or South-West Land Drainage Company's Act (11th and 12th Vict., cap. 142), for the purpose of draining, irrigation and warping, embanking, reclaiming and inclosing, and road-making.

3d, The General Land-Drainage and Improvement Company's Act (12th and 13th Vict., cap. 91), for the purposes of draining, irrigating and warping, embanking, reclaiming and inclosing, road-making, and erecting farm-buildings.

4th, The Lands Improvement Company's Act (16th and 17th Vict., cap. 154), for the same purposes as the above, with the addition of planting for shelter. This company's powers extend to Scotland.

By these acts ample provision is made for rendering the dormant capital of the country available for the improvement of its soil. To the owners of entailed estates they are peculiarly valuable, from the power which they give to them of charging the cost of draining, &c., upon the inheritance. If such owners apply their own private funds in effecting such improvements, they are enabled, through the medium of these companies, to take a rent-charge on their estates for the repayment of money which they so expend, over which they retain personal control, so that they can bequeath as they choose the rent-charge payable by their successor. Besides their direct benefits, these drainage acts have already produced some very important indirect fruits. They have led to many improvements in the manner of accomplishing the works to which they relate, to the wide and rapid dissemination of such improved modes of draining, &c., and, in particular, they have had the effect of creating, or at least of greatly multiplying and accrediting, a staff of skilful and experienced draining engineers, of whose services all who are about to engage in draining and similar works will do well to avail themselves.

(J.W.—N.)