DRAINAGE WITH TILES.
What are Drain-Tiles?--Forms of Tiles.--Pipes.--Horse-shoe
Tiles.--Sole-Tiles--Form of Water-Passage.--Collars and their
Use.--Size of Pipes.--Velocity.--Friction.--Discharge of Water
through Pipes.--Tables of Capacity.--How Water enters Tiles.--Deep
Drains run soonest and longest.--Pressure of Water on
Pipes.--Durability of Tile Drains.--Drain-Bricks 100 years old.
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.
[Illustration: Fig. 26.--DRAINING-BRICKS.]
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.
[Illustration: Figs. 27, 28, 29.--ROUND PIPES.]
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.
[Illustration: Fig. 30--HORSE-SHOE TILES AND SOLES.]
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:
"We shall shock and surprise many of our readers, when we state
confidently that, in average soils, and still more in those which
are inclined to be tender, horse-shoe tiles form the weakest and
most failing conduit which has ever been used for a deep drain. It
is so, however; and a little thought, even if we had no experience,
will tell us that it must be so.
"A horse-shoe tile, which may be a tolerably secure conduit in a
drain of 2 feet, in one of 4 feet becomes an almost certain
failure. As to the longitudinal fracture, not only is the tile
subject to be broken by one of those slips which are so troublesome
in deep draining, and to which the lightly-filled material, even
when the drain is completed, offers an imperfect resistance, but
the constant pressure together of the sides, even when it does not
produce a fracture of the soil, catches hold of the feet of the
tile, and breaks it through the crown. When the Regent's Park was
first drained, large conduits were in fashion, and they were made
circular by placing one horse-shoe tile upon another. It would be
difficult to invent a weaker conduit. On re-drainage, innumerable
instances were found in which the upper tile was broken through the
crown and had dropped into the lower."
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.
[Illustration: Fig. 31--SOLE-TILE.]
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.
[Illustration: Fig. 32.--PIPES AND COLLAR.]
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:
"We were astounded to find, at the conclusion of Mr. Parkes'
Newcastle Lecture, this sentence: 'It may be advisable for me to
say, that in clays, and other clean-cutting and firm-bottomed
soils, I do not find the collars to be indispensably necessary,
although I always prefer their use.' This is a barefaced treachery
to pipes, an abandonment of the strongest point in their case--the
assured continuity of the conduit. Every one may see how very small
a disturbance at their point of junction would dissociate two pipes
of one inch diameter. One finds a soft place in the bottom of the
drain and dips his nose into it one inch deep, and cocks up his
other end. By this simple operation, the continuity of the conduit
is twice broken. An inch of lateral motion produces the same
effect. Pipes of a larger diameter than two inches are generally
laid without collars. This is a practice on which we do not look
with much complacency; it is the compromise between cost and
security, to which the affairs of men are so often compelled. No
doubt, a conduit from three to six inches in diameter is much less
subject to a breach in its continuity than one which is smaller;
but, when no collars are used, the pipes should be laid with
extreme care, and the bed which is prepared for them at the bottom
of the drain should be worked to their size and shape with great
accuracy.
"To one advantage which is derived from the use of collars we have
not yet adverted--the increased facility with which free water
existing in the soil can find entrance into the conduit.
"The collar for a one and a half inch pipe has a circumference of
nine inches. The whole space between the collar and the pipe, on
each side of the collar, is open, and affords no resistance to the
entrance of water: while, at the same time, the superincumbent arch
of the collar protects the junction of two pipes from the intrusion
of particles of soil. We confess to some original misgivings, that
a pipe resting only on an inch at each end, and lying hollow, might
prove weak, and liable to fracture by weight pressing on it from
above; but the fear was illusory. Small particles of soil trickle
down the sides of every drain, and the first flow of water will
deposit them in the vacant space between the two collars. The
bottom, if at all soft, will also swell up into any vacancy.
Practically, if you re-open a drain well laid with pipes and
collars, you will find them reposing in a beautiful nidus, which,
when they are carefully removed, looks exactly as if it had been
moulded for them."
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:
"It may be advisable for me to say, that in clays, and other
clean-cutting and firm-bottomed soils, I do not find collars to be
at all necessary; but that they are essential in all sandy, loose,
and soft strata."
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 use of collars is by no means general, although those who have
used them speak highly of their advantages. Except in sandy soils,
and in those that are subject to sudden alteration of character, in
some of the deposits of red sand-stones, and in the clayey subsoils
of the Bagshot sand district, for instance, collars are not found
to be essential to good drainage. In the north of England they are
used but seldom, and, in my opinion, much less than they ought to
be; but this opinion, it is right to state, is opposed, in numerous
instances of successful drainage, by men of extensive practice; and
as every cause of increased outlay is to be avoided, the value of
collars, as general appliances, remains an open question. In all
the more porous subsoils in which collars have not been used, the
more successful drainers increase the size of the pipes in the
minor drains to a minimum size of two inches bore."
_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.
[Illustration: Fig. 33--FLAT-BOTTOMED PIPE-TILE.]
From an English report on the drainage of towns, the following, which
illustrates this point, is taken:
"It was found that a large proportion of sewers were constructed
with flat bottoms, which, when there was a small discharge, spread
the water, increased the friction, retarded the flow, and
accumulated deposit. It was ascertained, that by the substitution
of circular sewers of the same width, with the same inclination and
the same run of water, the amount of deposit was reduced more than
one-half."
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,
"it was found that, with pipes of the same diameter, exactitude of
form was of more importance than smoothness of surface; that glass
pipes, which had a wavy surface, discharged less water, at the same
inclinations, than Staffordshire stone-ware clay pipes, which were
of perfectly exact construction. By passing pipes of the same
clay--the common red clay--under a second pressure, obtained by a
machine at an extra expense of about eighteen pence per thousand,
whilst the pipe was half dry, very superior exactitude of form was
obtained, and by means of this exactitude, and with nearly the same
diameters, an increased discharge of water of one-fourth was
effected within the same time."
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.
"On a large scale, it was found that when equal quantities of water
were running direct, at a rate of 90 seconds, with a turn at
right-angles, the discharge was only effected in 140 seconds;
whilst, with a turn or junction with a gentle curve, the discharge
was effected in 100 seconds."
We are indebted to Messrs. Shedd & Edson for the following valuable
tables showing the capacity of water-pipes, with the accompanying
suggestions:
"DISCHARGE OF WATER THROUGH PIPES.
"The following tables of discharge are founded on the experiments
made by Mr. Smeaton, and have been compared with those by Henry
Law, and with the rules of Weisbach and D'Aubuisson. The conditions
under which such experiments are made may be so essentially
different in each case, that few experiments give results
coincident with each other, or with the deductions of theory: and
in applying these tables to practice, it is quite likely that the
discharge of a pipe of a certain area, at a certain inclination,
may be quite unlike the discharge found to be due to those
conditions by this table, and that difference may be owing partly
to greater or less roughness on the inside of the pipe, unequal
flow of water through the joints into the pipe, crookedness of the
pipes, want of accuracy in their being placed, so that the fall may
not be uniform throughout, or the ends of the pipes may be shoved a
little to one side, so that the continuity of the channel is
partially broken; and, indeed, from various other causes, all of
which may occur in any practical case, unless great care is taken
to avoid it, and some of which may occur in almost any case.
"We have endeavored to so construct the tables that, in the
ordinary practice of draining, the discharge given may approximate
to the truth for a well laid drain, subject even to considerable
friction. The experiments of Mr. Smeaton, which we have adopted as
the basis of these tables, gave a less quantity discharged, under
certain conditions, than given under similar conditions by other
tables. This result is probably due to a greater amount of friction
in the pipes used by Smeaton. The curves of friction resemble, very
nearly, parabolic curves, but are not quite so sharp near the
origin.
"We propose, during the coming season, to institute some careful
experiments, to ascertain the friction due to our own drain-pipe.
Water can get into the drain-pipe very freely at the joints, as may
be seen by a simple calculation. It is impossible to place the ends
so closely together, in laying, as to make a tight joint on account
of roughness in the clay, twisting in burning, &c.; and the opening
thus made will usually average about one-tenth of an inch on the
whole circumference, which is, on the inside of a two-inch pipe,
six inches--making six-tenths of a square inch opening for the
entrance of water at each joint.
"In a lateral drain 200 feet long, the pipes being thirteen inches
long, there will be 184 joints, each joint having an opening of
six-tenth square inch area; in 184 joints there is an aggregate
area of 110 square inches; the area of the opening at the end of a
two-inch pipe is about three inches; 110 square inches inlet to
three inches outlet; thirty-seven times as much water can flow in
as can flow out. There is, then, no need for the water to go
through the pores of the pipe; and the fact is, we think, quite
fortunate, for the passage of water through the pores would in no
case be sufficient to benefit the land to much extent. We tried an
experiment, by stopping one end of an ordinary drain-pipe and
filling it with water. At the end of sixty-five hours, water still
stood in the pipe three-fourths of an inch deep. About half the
water first put into the pipe had run out at the end of twenty-four
hours. If the pipe was stopped at both ends and plunged four feet
deep in water, it would undoubtedly fill in a short time; but such
a test is an unfair one, for no drain could be doing service, over
which water could collect to the depth of four feet."
1-1/2-INCH DRAIN-PIPE.
Area: 1.76709 inches.
====================================================================
FALL | VELOCITY | DISCHARGE || FALL | VELOCITY | DISCHARGE
in |per second| in gallons || in |per second| in gallons
100 feet.| in feet. |in 24 hours.||100 feet.| in feet. |in 24 hours.
---------+----------+------------++---------+----------+------------
ft. in. | | || ft. in. | |
0.3 | 0.71 | 5630.87 || 5.3 | 3.75 | 29704.51
0.6 | 1.04 | 8248.03 || 5.6 | 3.84 | 30454.28
0.9 | 1.29 | 10230.73 || 5.9 | 3.93 | 31168.06
1.0 | 1.52 | 12054.81 || 6.0 | 4.00 | 31723.21
1.3 | 1.74 | 13799.59 || 6.3 | 4.10 | 32516.36
1.6 | 1.91 | 15147.83 || 6.6 | 4.18 | 33150.76
1.9 | 2.10 | 16654.68 || 6.9 | 4.25 | 33705.91
2.0 | 2.26 | 17923.61 || 7.0 | 4.33 | 34340.38
2.3 | 2.41 | 19113.23 || 7.3 | 4.41 | 34974.85
2.6 | 2.56 | 20302.86 || 7.6 | 4.49 | 35609.30
2.9 | 2.69 | 21333.86 || 7.9 | 4.56 | 36154.45
3.0 | 2.83 | 22444.17 || 8.0 | 4.65 | 36878.23
3.3 | 2.94 | 23150.71 || 8.3 | 4.71 | 37354.08
3.6 | 3.06 | 24268.25 || 8.6 | 4.79 | 37988.55
3.9 | 3.16 | 25061.34 || 8.9 | 4.85 | 38464.40
4.0 | 3.28 | 26013.03 || 9.0 | 4.91 | 38940.25
4.3 | 3.38 | 26806.11 || 9.3 | 4.98 | 39495.39
4.6 | 3.46 | 27440.58 || 9.6 | 5.04 | 39971.24
4.9 | 3.56 | 28233.66 || 9.9 | 5.10 | 40447.10
5.0 | 3.65 | 28947.43 || 10.0 | 5.16 | 40922.93
====================================================================
====================================================================
||
2-INCH DRAIN-PIPE. || 3-INCH DRAIN-PIPE.
||
---------+----------+------------++---------+----------+------------
FALL | VELOCITY | DISCHARGE || FALL | VELOCITY | DISCHARGE
in |per second| in gallons || in |per second| in gallons
100 feet.| in feet. |in 24 hours.||100 feet.| in feet. |in 24 hours.
---------+----------+------------++---------+----------+------------
ft. in. | | || ft. in. | |
0.3 | 0.79 | 10575.4 || 0.3 | 0.90 | 24687.2
0.6 | 1.16 | 15528.4 || 0.6 | 1.33 | 36482.2
0.9 | 1.50 | 20079.9 || 0.9 | 1.66 | 45534.2
1.0 | 1.71 | 22891.1 || 1.0 | 1.94 | 53214.7
1.3 | 1.94 | 25970.0 || 1.3 | 2.19 | 60072.2
1.6 | 2.16 | 28915.1 || 1.6 | 2.43 | 66655.5
1.9 | 2.35 | 31458.5 || 1.9 | 2.63 | 72141.5
2.0 | 2.53 | 33868.1 || 2.0 | 2.83 | 77627.6
2.3 | 2.69 | 36009.9 || 2.3 | 3.00 | 82290.7
2.6 | 2.83 | 37884.0 || 2.6 | 3.16 | 86679.6
2.9 | 2.97 | 39758.2 || 2.9 | 3.31 | 90794.1
3.0 | 3.11 | 41632.4 || 3.0 | 3.47 | 95182.9
3.3 | 3.24 | 43372.6 || 3.3 | 3.60 | 98748.9
3.6 | 3.36 | 44979.0 || 3.6 | 3.74 | 102589.1
3.9 | 3.48 | 46585.4 || 3.9 | 3.87 | 106155.0
4.0 | 3.59 | 48057.9 || 4.0 | 3.99 | 109446.7
4.3 | 3.70 | 49530.5 || 4.3 | 4.11 | 112738.3
4.6 | 3.80 | 50869.1 || 4.6 | 4.23 | 116029.9
4.9 | 3.91 | 52341.6 || 4.9 | 4.34 | 119047.3
5.0 | 4.02 | 53814.1 || 5.0 | 4.46 | 122338.9
5.3 | 4.11 | 55018.9 || 5.3 | 4.57 | 125356.2
5.6 | 4.22 | 56491.5 || 5.6 | 4.68 | 128373.5
5.9 | 4.31 | 57696.3 || 5.9 | 4.78 | 131116.6
6.0 | 4.40 | 58901.1 || 6.0 | 4.89 | 134133.9
6.3 | 4.49 | 60105.9 || 6.3 | 4.98 | 136602.6
6.6 | 4.58 | 61309.7 || 6.6 | 5.08 | 139345.6
6.9 | 4.66 | 62381.6 || 6.9 | 5.18 | 142088.7
7.0 | 4.74 | 63452.5 || 7.0 | 5.27 | 144557.4
7.3 | 4.83 | 64667.3 || 7.3 | 5.37 | 147306.4
7.6 | 4.91 | 65728.3 || 7.6 | 5.46 | 150069.1
7.9 | 4.99 | 66799.2 || 7.9 | 5.55 | 152237.8
8.0 | 5.07 | 67870.1 || 8.0 | 5.64 | 154706.6
8.3 | 5.15 | 68941.0 || 8.3 | 5.73 | 157175.3
8.6 | 5.23 | 70011.9 || 8.6 | 5.82 | 159644.0
8.9 | 5.31 | 71082.8 || 8.9 | 5.91 | 162112.7
9.0 | 5.38 | 72019.9 || 9.0 | 5.99 | 164313.2
9.3 | 5.46 | 73090.9 || 9.3 | 6.07 | 166501.6
9.6 | 5.53 | 74027.9 || 9.6 | 6.16 | 168970.3
9.9 | 5.60 | 74965.0 || 9.9 | 6.24 | 171164.7
10.0 | 5.67 | 75902.0 || 10.0 | 6.32 | 173359.1
====================================================================
====================================================================
||
4-INCH DRAIN-PIPE. || 5-INCH DRAIN-PIPE.
||
---------+----------+------------++---------+----------+------------
FALL | VELOCITY | DISCHARGE || FALL | VELOCITY | DISCHARGE
in |per second|in gallons || in |per second| in gallons
100 feet.| in feet. |in 24 hours.||100 feet.| in feet. |in 24 hours.
---------+----------+------------++---------+----------+------------
ft. in. | | || ft. in. | |
0.3 | 1.08 | 43697.6 || 0.3 | 1.13 | 99584.2
0.6 | 1.50 | 60691.2 || 0.6 | 1.57 | 138362.4
0.9 | 1.83 | 74043.2 || 0.9 | 1.90 | 167442.6
1.0 | 2.13 | 86181.4 || 1.0 | 2.20 | 193881.0
1.3 | 2.38 | 96296.6 || 1.3 | 2.45 | 215912.9
1.6 | 2.61 | 105602.6 || 1.6 | 2.70 | 237944.9
1.9 | 2.81 | 113694.8 || 1.9 | 2.90 | 255569.5
2.0 | 3.00 | 121382.3 || 2.0 | 3.10 | 273195.9
2.3 | 3.19 | 129089.9 || 2.3 | 3.29 | 289940.1
2.6 | 3.36 | 135948.2 || 2.6 | 3.46 | 304921.9
2.9 | 3.53 | 142826.5 || 2.9 | 3.64 | 320784.9
3.0 | 3.68 | 148895.7 || 3.0 | 3.80 | 334885.4
3.3 | 3.82 | 154560.2 || 3.3 | 3.96 | 348974.8
3.6 | 3.96 | 160224.7 || 3.6 | 4.11 | 362204.9
3.9 | 4.10 | 165889.2 || 3.9 | 4.26 | 375424.1
4.0 | 4.24 | 171553.7 || 4.0 | 4.40 | 387762.1
4.3 | 4.37 | 176813.6 || 4.3 | 4.52 | 398337.5
4.6 | 4.50 | 182073.5 || 4.6 | 4.66 | 410675.3
4.9 | 4.62 | 186928.3 || 4.9 | 4.78 | 421250.6
5.0 | 4.75 | 192188.7 || 5.0 | 4.90 | 430825.0
5.3 | 4.86 | 196639.4 || 5.3 | 5.02 | 442401.3
5.6 | 4.97 | 201090.1 || 5.6 | 5.14 | 452976.6
5.9 | 5.09 | 205945.3 || 5.9 | 5.25 | 462670.6
6.0 | 5.20 | 210396.0 || 6.0 | 5.37 | 473246.0
6.3 | 5.30 | 214442.1 || 6.3 | 5.49 | 483820.4
6.6 | 5.41 | 218892.8 || 6.6 | 5.60 | 493514.6
6.9 | 5.51 | 222938.8 || 6.9 | 5.70 | 502327.4
7.0 | 5.61 | 226984.9 || 7.0 | 5.80 | 511140.2
7.3 | 5.71 | 231031.0 || 7.3 | 5.90 | 520052.0
7.6 | 5.81 | 235077.1 || 7.6 | 6.00 | 528766.5
7.9 | 5.91 | 239123.2 || 7.9 | 6.10 | 537578.7
8.0 | 6.01 | 243169.2 || 8.0 | 6.20 | 546391.5
8.3 | 6.10 | 246810.7 || 8.3 | 6.30 | 555204.5
8.6 | 6.19 | 250452.2 || 8.6 | 6.40 | 564017.0
8.9 | 6.28 | 255493.7 || 8.9 | 6.49 | 571948.0
9.0 | 6.37 | 257735.2 || 9.0 | 6.58 | 579880.0
9.3 | 6.45 | 260971.9 || 9.3 | 6.66 | 586930.2
9.6 | 6.54 | 264603.1 || 9.6 | 6.75 | 594861.4
9.9 | 6.63 | 268254.9 || 9.9 | 6.84 | 602793.2
10.0 | 6.71 | 271491.8 || 10.0 | 6.93 | 610723.8
====================================================================
8-INCH DRAIN-PIPE.
Area: 50.2640 inches.
====================================================================
FALL | VELOCITY | DISCHARGE || FALL | VELOCITY | DISCHARGE
in |per second|in gallons || in |per second| in gallons
100 feet.| in feet. |in 24 hours.||100 feet.| in feet. |in 24 hours.
---------+----------+------------++---------+----------+------------
ft. in. | | || ft. in. | |
0.3 | 1.23 | 277487.7 || 5.3 | 5.35 | 1206959.3
0.6 | 1.65 | 372239.7 || 5.6 | 5.47 | 1234031.3
0.9 | 2.01 | 453455.7 || 5.9 | 5.59 | 1261103.3
1.0 | 2.33 | 525647.7 || 6.0 | 5.71 | 1288175.3
1.3 | 2.60 | 586559.7 || 6.3 | 5.83 | 1315247.3
1.6 | 2.85 | 642959.6 || 6.6 | 5.95 | 1343838.9
1.9 | 3.08 | 694847.6 || 6.9 | 6.07 | 1369391.3
2.0 | 3.30 | 744479.7 || 7.0 | 6.17 | 1391951.2
2.3 | 3.50 | 789599.6 || 7.3 | 6.27 | 1414531.1
2.6 | 3.70 | 844719.7 || 7.6 | 6.39 | 1441583.2
2.9 | 3.89 | 877583.5 || 7.9 | 6.50 | 1466399.3
3.0 | 4.05 | 913679.5 || 8.0 | 6.60 | 1488959.2
3.3 | 4.21 | 949775.6 || 8.3 | 6.70 | 1511539.1
3.6 | 4.37 | 971658.7 || 8.6 | 6.80 | 1534099.0
3.9 | 4.53 | 920447.4 || 8.9 | 6.90 | 1556658.9
4.0 | 4.67 | 1055551.4 || 9.0 | 7.00 | 1579199.3
4.3 | 4.81 | 1086135.4 || 9.3 | 7.10 | 1601759.2
4.6 | 4.95 | 1116718.7 || 9.6 | 7.20 | 1624319.1
4.9 | 5.08 | 1146047.4 || 9.9 | 7.29 | 1644622.1
5.0 | 5.22 | 1177631.3 || 10.0 | 7.38 | 1664927.1
====================================================================
HOW WATER ENTERS THE TILES.
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--
"The pressure due to a head of water four or five feet, may be
imagined from the force with which water will come through the
crevices of a hatch with that depth of water above it. Now, there
is the same pressure of water to enter the vacuum in the pipe-drain
as there is against the hatches, supposing the land to be full of
water to the surface."
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:
"Of the durability of common brick, when used in drains, there is a
remarkable instance mentioned by Mr. George Guthrie, factor to the
Earl of Stair or Calhoun, Wigtonshire. In the execution of modern
draining on that estate, some brick-drains, on being intersected,
emitted water very freely. According to documents which refer to
these drains, it appears that they had been formed by the
celebrated Marshal, Earl Stair, _upwards of a hundred years ago_.
They were found between the vegetable mould and the clay upon which
it rested, between the 'wet and the dry,' as the country phrase has
it, and about thirty-one inches below the surface. They presented
two forms--one consisting of two bricks set asunder on edge, and
the other two laid lengthways across them, leaving between them an
opening of four inches square for water, but having no soles. The
bricks had not sunk in the least through the sandy clay bottom upon
which they rested, as they were three inches broad. The other form
was of two bricks laid side by side, as a sole, with two others
built or laid on each other, at both sides, upon the solid ground,
and covered with flat stones, the building being packed on each
side of the drain with broken bricks."
In our chapter upon the "Obstruction of Drains," the various causes
which operate against the permanency of drains, are more fully
considered.