WHAT ARE DRAIN-TILES?

This would be an absurd question to place at the head of a division in a work intended for the English public, for tiles are as common in England as bricks, and their forms and uses as familiar to all. But in America, though tiles are used to a considerable extent in some localities, probably not one farmer in one hundred in the whole country ever saw one.

The author has recently received letters of inquiry about the use and cost of tiles, from which it is manifest that the writers have in their mind as tiles, the square bricks with which our grandfathers used to lay their hearths.

In Johnstone's Report to the Board of Agriculture on Elkington's System of Draining, published in England in 1797, the only kind of tiles or clay conduits described or alluded to by him, are what he calls "draining-bricks," of which he gives drawings, which we transfer to our pages precisely as found in the American edition. It will be seen to be as clumsy a contrivance as could well be devised.

So lately as 1856, tiles were brought from Albany, N. Y., to Exeter, N. H., nearly 300 miles, by railway, at a cost, including freight, of $25 a thousand for two-inch pipes, and it is believed that no tiles were ever made in New Hampshire till the year 1857. These facts will soon become curiosities in agricultural literature, and so are worth preserving. They furnish excuse, too, for what may appear to learned agriculturists an unnecessary particularity in what might seem the well-known facts relative to tile-drainage.

Drain-tiles are made of clay of almost any quality that will make bricks, moulded by a machine into tubes, or into half-tube or horse-shoe forms, usually fourteen inches long before drying, and burnt in a furnace or kiln to be about as hard as what are called hard-burnt bricks. They are usually moulded about half an inch in thickness, varying with the size and form of the tile. The sizes vary from one inch to six inches, and sometimes larger, in the diameter of the bore. The forms are also very various; and as this is one of the most essential matters, as affecting the efficiency, the cost, and the durability of tile-drainage, it will be well to give it critical attention.

THE FORMS OF TILES.

The simplest, cheapest, and best form of drain-tile is the cylinder, or merely a tube, round outside and with a round bore.

Tiles of this form, and all others which are tubular, are called pipes, in distinction from those with open bottoms, like those of horse-shoe form.

About forty years ago, as Mr. Gisborne informs us, small pipes for land-drainage were used, concurrently, by persons residing in the counties of Lincoln, Oxford, and Kent, who had, probably, no knowledge of each other's operations. Most of those pipes were made with eyelet-holes, to admit the water. Pipes for thorough-draining excited no general attention till they were exhibited by John Read at the show at Derby, in the year 1843. A medal was awarded to the exhibitor. Mr. Parkes was one of the judges, and brought the pipes to the special notice of the council. From this time, inventions and improvements were rapid, and soon, collars were introduced, and the use of improved machines to mould the pipes; and drainage, under the fostering influence of the Royal Agricultural Society, became a subject of general attention throughout the kingdom. The round pipe, or the pipe, as it seems, par excellence, to be termed by English drainers, though one of the latest, if not the last form of tiles introduced in England, has become altogether the most popular among scientific men, and is generally used in all works conducted under the charge of the Land Drainage Companies. This ought to settle the question for us, when we consider that the immense sum of twenty millions of dollars of public funds has been expended by them, in addition to vast amounts of private funds, and that the highest practical talent of the nation is engaged in the work.

After giving some idea of the various forms of tiles in use, it is, however, proposed to examine the question upon its merits, so that each may judge for himself which is best.

The earliest form of tiles introduced for the purpose of thorough-drainage, was the horse-shoe tile, so called from its shape. The horse-shoe tile has been sometimes used without any sole to form the bottom of the drain, thus leaving the water to run on the ground. There can hardly be a question of the false economy of this mode, for the hardest and most impervious soil softens under the constant action of running water, and then the edges of the tiles must sink, or the bottom of the drain rise, and thus destroy the work.

Various devices have been tried to save the expense of soles, such as providing the edges of the tiles with flanges or using pieces of soles on which to rest the ends of the tiles. They all leave the bottom of the drain unprotected against the wearing action of the water.

Horse-shoe tiles, or "tops and bottoms" as they are called in some counties, are still much used in England; and in personal conversation with farmers there, the writer found a strong opinion expressed in their favor. The advantages claimed for the "tops and bottoms" are, that they lie firmly in place, and that they admit the water more freely than others.

The objections to them are, that they are more expensive than round pipes, and are not so strong, and are not so easily laid, and that they do not discharge water so well as tiles with a round bore. In laying them, they should be made to rest partly upon two adjoining soles, or to break bond, as it is called. The soles are made separate from the tiles, and are merely flat pieces, of sufficient width to support firmly both edges of the tiles. The soles are usually an inch wider than the tiles.

The above figure represents the horse-shoe tiles and soles properly placed.

As this form of tile has been generally used by the most successful drainers in New York, it may be well to cite the high authority of Mr. Gisborne for the objections which have been suggested. It should be recollected in this connection, that the drainage in this country has been what in England would be called shallow, and that it is too recent to have borne the test of time.

Mr. Gisborne says:

Another form of tiles, called sole-tiles, or sole-pipes, is much used in America, more indeed than any other, except perhaps the horse-shoe tile; probably, because the first manufacturers fancied them the best, and offered no others in the market.

In this form, the sole is solid with the tile. The bottom is flat, but the bore is round, or oval, or egg-shaped, with the small end of the orifice downward.

The sole-pipe has considerable advantages theoretically. The opening or bore is of the right shape, the bottom lies fair and firm in place, and the drain, indeed, is perfect, if carefully and properly laid.

The objections to the sole-pipes are, that they are somewhat more expensive than round pipes, and that they require great care in placing them, so as to make the passage even from one pipe to another.

A slight depression of one side of a pipe of this kind, especially if the bore be oval or egg-shaped, throws the water passage out of line. In laying them, the author has taken the precaution to place under each joint a thin piece of wood, such as our honest shoe manufacturers use for stiffening in shoes, to keep the bottoms of the pipes even, at least until the ground has settled compactly, and as much longer as they may escape "decay's effacing finger."

Collars for tiles are used wherever a sudden descent occurs in the course of a drain, or where there is a loose sand or a boggy place, and by many persons they are used in all drains through sandy or gravelly land.

The above figure represents pipe-tiles fitted with collars. Collars are merely short sections of pipes of such size as to fit upon the smaller ones loosely, covering the joint, and holding the ends in place, so that they cannot slip past each other. In very bad places, small pipes may be entirely sheathed in larger ones; and this is advisable in steep descents or flowing sands.

A great advantage in round pipes is, that there is no wrong-side-up to them, and they are, therefore, more readily placed in position than tiles of any other form.

Again: all tiles are more or less warped in drying and burning; and, where it is desired to make perfect work, round pipes may be turned so as to make better joints and a straighter run for the water—which is very important.

If collars are used, there is still less difficulty in adjusting the pipes so as to make the lines straight, and far less danger of obstruction by sand or roots. Indeed, it is believed that no drain can be made more perfect than with round pipes and collars.

As it is believed that few collars have ever yet been used in this country, and the best drainers in England are not agreed as to the necessity of using them, we give the opinions of two or three distinguished gentlemen, in their own language. Mr. Gisborne says:

As to the danger of breaking the pipes, which might well be apprehended, we found by actual experiment, at the New York Central Park, that a one-inch Albany pipe resting on collars upon a floor, with a bearing at each end of but one inch, would support the weight of a man weighing 160 pounds, standing on one foot on the middle of the pipe.

Mr. Parkes sums up his opinion upon the subject of collars, in these words:

In draining in the neighborhood of trees, collars are also supposed to be of great use in preventing the intrusion of roots into the pipes, although it may be impossible, even in this way, to exclude the roots of water-loving trees.

From the most careful inquiry that the writer was able to make, as to the practice in England, he is satisfied that collars are not generally used there in the drainage of clays, but that the pipes are laid in openings shaped for them at the bottom of the drains, with a tool which forms a groove into which the pipes fall readily into line, and very little seems to be said of collars in the published estimates of the cost of drainage.

On this subject, we have the opinion of Mr. Denton, thus expressed:

The form of the bore, or water passage, in tiles, is a point of more importance than at first appears. At one of our colleges, certain plank sewers, in the ordinary square form, were often obstructed by the sediment from the dirty water. "Turn them cornerwise," suggested the professor of Natural Philosophy. It was done, and ever after they kept in order. The pressure of water depends on its height, or head. Everybody knows that six feet of water carries a mill-wheel better than one foot. The same principle operates on a small scale. An inch head of water presses harder than a half inch. The velocity of water, again, depends much on its height. Whether there be much or little water passing through a drain, it has manifestly a greater power to make its way, to drive before it sand or other obstructions, when it is heaped up in a round passage, than when wandering over the flat surface of a tile sole. Any one who has observed the discharge of water from flat-bottomed and round tiles, will be satisfied that the quantity of water which is sufficient to run in a rapid stream of a half or quarter inch diameter from a round tile, will lazily creep along the flat bottom of a sole tile, with hardly force sufficient to turn aside a grain of sand, or to bring back to light an enterprising cricket that may have entered on an exploration. On the whole, solid tiles, with flat-bottomed passages, may be set down among the inventions of the adversary. They have not the claims even of the horse-shoe form to respect, because they do not admit water better than round pipes, and are not united by a sole on which the ends of the adjoining tiles rest. They combine the faults of all other forms, with the peculiar virtues of none.

From an English report on the drainage of towns, the following, which illustrates this point, is taken:

THE SIZE OF TILES.

Is a matter of much importance, whether we regard the efficiency and durability of our work, or economy in completing it. The cost of tiles, and the freight of them, increase rapidly with their size, and it is, therefore, well to use the smallest that will effect the object in view. Tiles should be large enough, as a first proposition, to carry off, in a reasonable time, all the surplus water that may fall upon the land. Here, the English rules will not be safe for us; for, although England has many more rainy days than we have, yet we have, in general, a greater fall of rain—more inches of water from the clouds in the year. Instead of their eternal drizzle, we have thunder showers in Summer, and in Spring and Autumn north-east storms, when the windows of heaven are opened, and a deluge, except in duration, bursts upon us. Then, at the North, the Winter snows cover the fields until April, when they suddenly dissolve, often under heavy showers of rain, and planting time is at once upon us. It is desirable that all the snow and rain-water should pass through the soil into the drains, instead of overflowing the surface, so as to save the elements of fertility with which such water abounds, and also to prevent the washing of the soil. We require, then, a greater capacity of drainage, larger tiles, than do the English, for our drains must do a greater work than theirs, and in less time.

There are several other general considerations that should be noticed, before we attempt to define the particular size for any location. Several small drains are usually discharged into one main drain. This main should have sufficient capacity to conduct all the water that may be expected to enter it, and no more. If the small drains overflow it, the main will be liable to be burst, or the land about it filled with water, gushing from it at the joints; especially, if the small drains come down a hill side, so as to give a great pressure, or head of water. On the other hand, if the main be larger than is necessary, there is the useless expense of larger tiles than were required. The capacity of pipes to convey water, depends, other things being equal, upon their size; but here the word size has a meaning which should be kept clearly in mind.

The capacity of round water-pipes is in proportion to the squares of their diameters.

A one-inch pipe carries one inch (circular, not square) of water, but a two-inch pipe carries not two inches only, but twice two, or four inches of water; a three-inch pipe carries three times three, or nine inches; and a four-inch pipe, sixteen inches. Thus we see, that under the same conditions as to fall, directness, smoothness, and the like, a four-inch pipe carries just four times as much water as a two-inch pipe. In fact, it will carry more than this proportion, because friction, which is an important element in all such calculations, is greater in proportion to the smaller size of the pipe.

Velocity is another essential element to be noticed in determining the amount of water which may be discharged through a pipe of given diameter. Velocity, again, depends on several conditions. Water runs faster down a steep hill than down a gentle declivity. This is due to the weight of the water, or, in other words, to gravitation, and operates whether the water be at large on the ground, or confined in a pipe, and it operates alike whether the water in a pipe fill its bore or not.

But, again, the velocity of water in a pipe depends on the pressure, or head of water, behind it, and there is, perhaps, no definite limit to the quantity of water that may be forced through a given orifice. More water, for instance, is often forced through the pipe of a fire-engine in full play, in ten minutes, than would run through a pipe of the same diameter, lying nearly level in the ground, in ten hours.

In ordinary aqueducts, for supplying water, and not for drainage, it is desirable to have a high pressure upon the pipes to ensure a rapid flow; but in drainage, a careful distinction must be made between velocity induced by gravitation, and velocity induced by pressure. If induced by the former merely, the pipe through which the water is swiftly running, if not quite full, may still receive water at every joint, while, if the velocity be induced by pressure, the pipe must be already full. It can then receive no more, and must lose water at the joints, and wet the land through which it passes, instead of draining it.

So that although we should find that the mains might carry a vast quantity of water admitted by minor drains from high elevations, yet we should bear in mind, that drains when full can perform no ordinary office of drainage. If there is more than the pressure of four feet head of water behind; the pipes, if they passed through a pond of water, at four feet deep, must lose and not receive water at the joints.

The capacity of a pipe to convey water depends, then, not only on its size, but on its inclination or fall—a pipe running down a considerable descent having much greater capacity than one of the same size lying nearly level. This fact should be borne in mind even in laying single drains; for it is obvious that if the drain lie along a sandy plain, for instance, extending down a springy hill-side, and then, as is usually the case, along a lower plain again, to its outlet at some stream, it may collect as much water as will fill it before it reaches the lower level. Its stream rushes swiftly down the descent, and when it reaches the plain, there is not sufficient fall to carry it away by its natural gravitation. It will still rush onward to its outlet, urged by the pressure from behind; but, with such pressure, it will, as we have seen, instead of draining the land, suffuse it with water.

FRICTION,

as has already been suggested, is an element that much interferes with exact calculations as to the relative capacity of water-pipes of various dimensions, and this depends upon several circumstances, such as smoothness, and exactness of form, and directness. The smoother, the more regular in form, and the straighter the drain, the more water will it convey. Thus, in some recent English experiments,

So all sudden turns or angles increase friction and retard velocity, and thus lessen the capacity of the drain—a topic which may be more properly considered under the head of the junction of drains.

We are indebted to Messrs. Shedd & Edson for the following valuable tables showing the capacity of water-pipes, with the accompanying suggestions:

How water enters the tiles, is a question which all persons unaccustomed to the operation of tile-draining usually ask at the outset. In brief, it may be answered, that it enters both at the joints and through the pores of the burnt clay, but mostly at the joints.

Mr. Parkes expresses the opinion, based upon careful observation, that five hundred times as much water enters at the crevices as through the pores of the tiles! If this be so, we may as well, for all practical purposes, regard the water as all entering at the joints. In several experiments which we have attempted, we have found the quantity of water that enters through the pores to be quite too small to be of much practical account.

Tiles differ so much in porosity, that it is difficult to make experiments that can be satisfactory—soft-burnt tiles being, like pale bricks, quite pervious, and hard-burnt tiles being nearly or quite impervious. The amount of pressure upon the clay in moulding also affects the density and porosity of tiles.

Water should enter at the bottom of the tiles, and not at the top. It is a well-known fact in draining, that the deepest drain flows first and longest. A familiar illustration will make this point evident. If a cask or deep box be filled with sand, with one hole near the bottom and another half way to the top, these holes will represent the tiles in a drain. If water be poured into the sand, it will pass downward to the bottom of the vessel, and will not flow out of either hole till the sand be saturated up to the lower hole, and then it will flow out there. If, now, water be poured in faster than the lower hole can discharge it, the vessel will be filled higher, till it will run out at both holes. It is manifest, however, that it will first cease to flow from the upper orifice. There is in the soil a line of water, called the "water-line," or "water-table;" and this, in drained land, is at about the level of the bottom of the tiles. As the rain falls it descends, as in the vessel; and as the water rises, it enters the tiles at the bottom, and never at the top, unless there is more than can pass out of the soil by the lower openings (the crevices and pores) into the tiles. It is well always to interrupt the direct descent of water by percolation from the surface to the top of the tiles, because, in passing so short a distance in the soil, the water is not sufficiently filtered, especially in soil so recently disturbed, but is likely to carry with it not only valuable elements of fertility, but also particles of sand, which may obstruct the drain. This is prevented by placing above the tiles (after they are covered a few inches with gravel, sand, or other porous soil) compact clay, if convenient. If not, a furrow each side of the drain, or a heaping-up of the soil over the drain, when finished, will turn aside the surface-water, and prevent such injury.

In the estimates as to the area of the openings between pipes, it should be considered that the spaces between the pipes are not, in fact, clean openings of one-tenth of an inch, but are partially closed by earthy particles, and that water enters them by no means as rapidly as it would enter the clean pipes before they are covered. Although the rain-fall in England is much less in quantity and much more regular than in this country, yet it is believed that the use of two-inch pipes will be found abundantly sufficient for the admission and conveyance of any quantity of water that it may be necessary to carry off by drainage in common soils. In extraordinary cases, as where the land drained is a swamp, or reservoir for water which falls on the hills around, larger pipes must be used.

In many places in England "tops and bottoms," or horse-shoe tiles, are still preferred by farmers, upon the idea that they admit the water more readily; but their use is continued only by those who have never made trial of pipes. No scientific drainer uses any but pipes in England, and the million of acres well drained with them, is pretty good evidence of their sufficiency. In this country, horse-shoe tiles have been much used in Western New York, and have been found to answer a good purpose; and so it may be said of the sole-pipes. Indeed, it is believed that no instance is to be found on record in America of the failure of tile drains, from the inability of the water to gain admission at the joints.

It may be interesting in this connection to state, that water is 815 times heavier than air. Here is a drain at four feet depth in the ground, filled only with air, and open at the end so that the air can go out. Above this open space is four feet of earth saturated with water. What is the pressure of the water upon the tiles?

Mr. Thomas Arkell, in a communication to the Society of Arts, in England, says—

It is difficult to demonstrate the truth of this theory; but the same opinion has been expressed to the writer by persons of learning and of practical skill, based upon observations as to the entrance of water into gas pipes, from which it is almost, if not quite, impossible to exclude it by the most perfect joints in iron pipes. Whatever be the theory as to pressure, or the difficulties as to the water percolating through compact soils to the tiles, there will be no doubt left on the mind of any one, after one experiment tried in the field, that, in common cases, all the surplus water that reaches the tiles is freely admitted. A gentleman, who has commenced draining his farm, recently, in New Hampshire, expressed to the author his opinion, that tiles in his land admitted the water as freely as a hole of a similar size to the bore of the tile would admit it, if it could be kept open through the soil without the tile.

DURABILITY OF TILE DRAINS.

How long will they last? This is the first and most important question. Men, who have commenced with open ditches, and, having become disgusted with the deformity, the inconvenience, and the inefficiency of them, have then tried bushes, and boards, and turf, and found them, too, perishable; and again have used stones, and after a time seen them fail, through obstructions caused by moles or frost—these men have the right to a well-considered answer to this question.

The foolish fellow in the Greek Reader, who, having heard that a crow would live a hundred years, purchased one to verify the saying, probably did not live long enough to ascertain that it was true. How long a properly laid tile-drain of hard-burnt tiles will endure, has not been definitely ascertained, but it is believed that it will outlast the life of him who lays it.

No tiles have been long enough laid in the United States to test this question by experience, and in England no further result seems to have been arrived at, than that the work is a permanent improvement.

In another part of this treatise, may be found some account of Land Drainage Companies, and of Government loans in aid of improvements by drainage in Great Britain. One of these acts provides for a charge on the land for such improvements, to be paid in full in fifty years. That is to say, the expense of the drainage is an incumbrance like a mortgage on the land, at a certain rate of interest, and the tenant or occupant of the land, each year pays the interest and enough more to discharge the debt in just fifty years. Thus, it is assumed by the Government, that the improvement will last fifty years in its full operation, because the last year of the fifty pays precisely the same as every other year.

It may therefore be considered as the settled conviction of all branches of the British government, and of all the best-informed, practical land-drainers in that country, that TILE-DRAINAGE WILL ENDURE FIFTY YEARS AT LEAST, if properly executed.

This is long enough to satisfy any American; for the migratory habits of our citizens, and the constant changes of cultivated fields into village and city lots, prevent our imagination even conceiving the idea that we or our posterity can remain for half a century upon the same farm.

It is much easier, however, to lay tile-drains so that they will not be of use half of fifty years, than to make them permanent in their effect. Tile-drainage, it cannot be too much enforced, is an operation requiring great care and considerable skill—altogether more care and skill than our common laborers, or even most of our farmers, are accustomed to exercise in their farm operations.

A blunder in draining, like the blunder of a physician, may be soon concealed by the grass that grows over it, but can never be corrected. Drainage is a new art in this country, and tile-making is a new art. Without good, hard-burnt tiles, no care or skill can make permanent work.

Tile-drainage will endure so long as the tiles last, if the work be properly done.

There is no reason why a tile should not last in the ground as long as a brick will last. Bricks will fall to pieces in the ground in a very short time if not hard-burnt, while hard-burnt bricks of good clay will last as long as granite.

Tiles must be hard-burnt in order to endure. But this is not all. Drains fail from various other causes than the crumbling of the tiles. They are frequently obstructed by mice, moles, frogs, and vermin of all kinds, if not protected at the outlet. They are often destroyed by the treading of cattle, and by the deposit of mud at the outlet, through insufficient care. They are liable to be filled with sand, through want of care in protecting the joints in laying, and through want of collars, and other means of keeping them in line. They are liable, too, to fill up by deposits of sand and the like, by being laid lower in some places than the parts nearer the outlet, so that the slack places catch and retain whatever is brought down, till the pipe is filled.

Frost is an enemy which in this country we have to contend with, more than in any other, where tile-drainage has been much practiced.

Upon all these points, remarks will be found under the appropriate heads; and these suggestions are repeated here, because we know that haste and want of skill are likely to do much injury to the cause which we advocate. Any work that requires only energy and progress, is safe in American hands; but cautious and slow operations are by no means to their taste.

Dickens says, that on railways and coaches, wherever in England they say, "All right," the Americans use, instead, the phrase, "Go ahead." In tile-drainage, the motto, "All right," will be found far more safe than the motto, "Go ahead."

Instances are given in England of drains laid with handmade tiles, which have operated well for thirty years, and have not yet failed.

Mr. Parkes informs us: "That, about 1804, pipe-tiles made tapering, with one end entering the other, and two inches in the smallest point, were laid down in the park now possessed by Sir Thomas Whichcote, Aswarby, Lincolnshire, and that they still act well."

Stephens gives the following instance of the durability of bricks used in draining:

In our chapter upon the "Obstruction of Drains," the various causes which operate against the permanency of drains, are more fully considered.