Читать книгу Farm drainage - Henry F. French - Страница 9

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It appears, that, in 1795, the British Parliament, at the request of the Board of Agriculture, voted to Joseph Elkington a reward of £1000, for his valuable discoveries in the drainage of land. Joseph Elkington was a Warwickshire farmer, and Mr. Gisborne says he was a man of considerable genius, but he had the misfortune to be illiterate. His discovery had created such a sensation in the agricultural world, that it was thought important to record its details; and, as Elkington's health was extremely precarious, the Board resolved to send Mr. John Johnstone to visit, in company with him, his principal works of drainage, and to transmit to posterity the benefits of his knowledge.

Accordingly, Mr. John Johnstone, having carefully studied Elkington's system, under its author, in the peripatetic method, undertook, like Plato, to record the sayings of his master in science, and produced a work, entitled, "An Account of the Most Approved Mode of Draining Land, According to the System Practised by Mr. Joseph Elkington." It was published at Edinburgh, in 1797. Mr. Gisborne says, that Elkington found in Johnstone "a very inefficient exponent of his opinions, and of the principles on which he conducted his works."

"Every one," says he, "who reads the work, which is popularly called 'Elkington on Draining,' should be aware, that it is not Joseph who thinks and speaks therein, but John, who tells his readers what, according to his ideas, Joseph would have thought and spoken."

Again—

"Johnstone, measured by general capacity, is a very shallow drainer! He delights in exceptional cases, of which he may have met with some, but of which, we suspect the great majority to be products of his own ingenuity, and to be put forward, with a view to display the ability with which he could encounter them."

Johnstone's report seems to have undergone several revisions, and to have been enlarged and reproduced in other forms than the original, for we find, that, in 1838, it was published in the United States, at Petersburg, Virginia, as a supplement to the Farmer's Register, by Edmund Ruffin, Esq., editor, a reprint "from the third British Edition, revised and enlarged," under the following title:

"A Systematic Treatise on the Theory and Practice of Draining Land, &c., according to the most approved methods, and adapted to the various situations and soils of England and Scotland; also on sea, river, and lake embankments, formation of ponds and artificial pieces of water, with an appendix, containing hints and directions for the culture and improvement of bog, morass, moor, and other unproductive ground, after being drained; the whole illustrated by plans and sections applicable to the various situations and forms of construction. Inscribed to the Highland and Agricultural Society of Scotland, by John Johnstone, Land Surveyor."

Mr. Ruffin certainly deserves great credit for his enterprise in republishing in America, at so early a day, a work of which an English copy could not be purchased for less than six dollars, as well as for his zealous labors ever since in the cause of agriculture.

There is, in this work of Johnstone, a quaintness which he, probably, did not learn from Elkington, and which illustrates the character of his mind as one not peculiarly adapted to a plain and practical history of another man's system and labors. For instance, in speaking of the arrangement of his subject into parts, he says, in a note, "The subject being closely connected with cutting, section is held as a better division than chapter!"

Again, he speaks of embanking, and says he has some experience on that head. Then he adds the following note, lest a possible pun should be lost: "An embankment is often termed a 'head,' as it makes head, or resistance, against the encroachment of high tide or river floods."

There is some danger that a mind which scents a whimsical analogy of meaning like this, may entirely lose the main track of pursuit; but Johnstone's special mission was to ascertain Elkington's method, and his account of it is, therefore, the best authority we have on the subject.

He gives the following statement of Elkington's discovery:

"In the year 1763, Elkington was left by his father in the possession of a farm called Prince-Thorp, in the parish of Stretton-upon-Dunsmore, and county of Warwick. The soil of this farm was so poor, and, in many places, so extremely wet, that it was the cause of rotting several hundreds of his sheep, which first induced him, if possible, to drain it. This he begun to do, in 1764, in a field of wet clay soil, rendered almost a swamp, or shaking bog, by the springs which issued from an adjoining bank of gravel and sand, and overflowed the surface of the ground below. To drain this field, which was of considerable extent, he cut a trench about four or five feet deep, a little below the upper side of the bog, where the wetness began to make its appearance; and, after proceeding with it in this direction and at this depth, he found it did not reach the principal body of subjacent water from which the evil arose. On perceiving this, he was at a loss how to proceed, when one of his servants came to the field with an iron crow, or bar, for the purpose of making holes for fixing sheep hurdles in an adjoining part of the farm, as represented on the plan. Having a suspicion that his drain was not deep enough, and desirous to know what strata lay under it, he took the iron bar, and having forced it down about four feet below the bottom of the trench, on pulling it out, to his astonishment, a great quantity of water burst up through the hole he had thus made, and ran along the drain. This led him to the knowledge, that wetness may be often produced by water confined farther below the surface of the ground than it was possible for the usual depth of drains to reach, and that an auger would be a useful instrument to apply in such cases. Thus, chance was the parent of this discovery, as she often is of other useful arts; and fortunate it is for society, when such accidents happen to those who have sense and judgment to avail themselves of hints thus fortuitously given. In this manner he soon accomplished the drainage of his whole farm, and rendered it so perfectly dry and sound, that none of his flock was ever after affected with disease.

"By the success of this experiment, Mr. Elkington's fame, as a drainer, was quickly and widely extended; and, after having successfully drained several farms in his neighborhood, he was, at last, very generally employed for that purpose in various parts of the kingdom, till about thirty years ago, when the country had the melancholy cause to regret his loss. From his long practice and experience, he became so successful in the works he undertook, and so skillful in judging of the internal strata of the earth and the nature of springs, that, with remarkable precision, he could ascertain where to find water, and trace the course of springs that made no appearance on the surface of the ground. During his practice of more than thirty years, he drained in various parts of England, particularly in the midland counties, many thousand acres of land, which, from being originally of little or no value, soon became as useful as any in the kingdom, by producing the most valuable kinds of grain and feeding the best and healthiest species of stock.

"Many have erroneously entertained an idea that Elkington's skill lay solely in applying the auger for the tapping of springs, without attaching any merit to his method of conducting the drains. The accidental circumstance above stated gave him the first notion of using an auger, and directed his attention to the profession and practice of draining, in the course of which he made various useful discoveries, as will be afterwards explained. With regard to the use of the auger, though there is every reason to believe that he was led to employ that instrument from the circumstance already stated, and did not derive it from any other source of intelligence, yet there is no doubt that others might have hit upon the same idea without being indebted for it to him. It has happened, that, in attempts to discover mines by boring, springs have been tapped, and ground thereby drained, either by letting the water down, or by giving it vent to the surface; and that the auger has been likewise used in bringing up water in wells, to save the expense of deeper digging; but that it had been used in draining land, before Mr. Elkington made that discovery, no one has ventured to assert."

Begging pardon of the shade of John Johnstone for the liberty, we will copy from Mr. Gisborne, as being more clearly expressed, a summary explanation of Elkington's system, as Mr. Gisborne has deduced it from Johnstone's report, with two simple and excellent plans:

"A slight modification of Johnstone's best and simplest plan, with a few sentences of explanation, will sufficiently elucidate Elkington's mystery, and will comprehend the case of all simple superficial springs. Perhaps in Agricultural Britain, no formation is more common than moderate elevations of pervious material, such as chalk, gravel, and imperfect stone or rock of various kinds, resting upon more horizontal beds of clay, or other material less pervious than themselves, and at their inferior edge overlapped by it. For this overlap geological reasons are given, into which we cannot now enter. In order to make our explanation simple, we use the words, gravel and clay, as generic for pervious and impervious material.

Fig. 1

"Our drawing is an attempt to combine plan and section, which will probably be sufficiently illustrative. From A to T is the overlap, which is, in fact, a dam holding up the water in the gravel. In this dam there is a weak place at S, through which water issues permanently (a superficial spring), and runs over the surface from S to O. This issue has a tendency to lower the water in the gravel to the line M m. But when continued rains overpower this issue, the water in the gravel rises to the line A a, and meeting with no impediment at the point A, it flows over the surface between A and S. In addition to these more decided outlets, the water is probably constantly squeezing, in a slow way, through the whole dam. Elkington undertakes to drain the surface from A to O. He cuts a drain from O to B, and then he puts down a bore-hole, an Artesian well, from B to Z. His hole enters the tail of the gravel; the water contained therein rises up it: and the tendency of this new outlet is to lower the water to the line B b. If so lowered that it can no longer overflow at A or at S, and the surface from A to O is drained, so far as the springs are concerned, though our section can only represent one spring, and one summit-overflow, it is manifest that, however long the horizontal line of junction between the gravel and clay may be, however numerous the weak places (springs) in the overlap, or dam, and the summit-overflows, they will all be stopped, provided they lie at a higher level than the line B b. If Elkington had driven his drain forward from B to n, he would, at least, equally have attained his object; but the bore-hole was less expensive. He escapes the deepest and most costly portion of his drain. At x, he might have bored to the centre of the earth without ever realizing the water in this gravel. His whole success, therefore, depended upon his sagacity in hitting the point Z. Another simple and very common case, first successfully treated by Elkington, is illustrated by our second drawing.

Fig. 2

"Between gravel hills lies a dish-shaped bed of clay, the gravel being continuous under the dish. Springs overflow at A and B, and wet the surface from A to O, and from B to O. O D is a drain four or five feet deep, and having an adequate outlet; D Z a bore-hole. The water in the gravel rises from Z to D, and is lowered to the level D m and D n. Of course it ceases to flow over at A and B. If Elkington's heart had failed him when he reached X, he would have done no good. All his success depends on his reaching Z, however deep it may lie. Elkington was a discoverer. We do not at all believe that his discoveries hinged on the accident that the shepherd walked across the field with a crow-bar in his hand. When he forced down that crow-bar, he had more in his head than was ever dreamed of in Johnstone's philosophy. Such accidents do not happen to ordinary men. Elkington's subsequent use of his discovery, in which no one has yet excelled him, warrants our supposition that the discovery was not accidental. He was not one of those prophets who are without honor in their own country: he created an immense sensation, and received a parliamentary grant of one thousand pounds. One writer compares his auger to Moses' rod, and Arthur Young speculates, whether though worthy to be rewarded by millers on one side of the hill for increasing their stream, he was not liable to an action by those on the other for diminishing theirs."

Johnstone sums up this system as follows:

"Draining according to Elkington's principles depends chiefly upon three things:

"1. Upon discovering the main spring, or source of the evil.

"2. Upon taking the subterraneous bearings: and,

"3dly. By making use of the auger to reach and tap the springs, when the depth of the drain is not sufficient for that purpose.

"The first thing, therefore, to be observed is, by examining the adjoining high grounds, to discover what strata they are composed of; and then to ascertain, as nearly as possible, the inclination of these strata, and their connection with the ground to be drained, and thereby to judge at what place the level of the spring comes nearest to where the water can be cut off, and most readily discharged. The surest way of ascertaining the lay, or inclination, of the different strata, is, by examining the bed of the nearest streams, and the edges of the banks that are cut through by the water; and any pits, wells, or quarries that may be in the neighborhood. After the main spring has been thus discovered, the next thing is, to ascertain a line on the same level, to one or both sides of it, in which the drain may be conducted, which is one of the most important parts of the operation, and one on which the art of draining in a scientific manner essentially depends.

"Lastly, the use of the auger, which, in many cases, is the sine qua non of the business, is to reach and tap the spring when the depth of the drain does not reach it: where the level of the outlet will not admit of its being cut to a greater depth; and where the expense of such cutting would be great, and the execution of it difficult.

"According to these principles, this system of draining has been attended with extraordinary consequences, not only in laying the land dry in the vicinity of the drain, but also springs, wells, and wet ground, at a considerable distance, with which there was no apparent connection."