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which Mr Eccleston with propriety calls the Miner, which is a ploughshare fixed in a strong beam, without mould-boards, and drawn by four or more horses, and follows in the furrow the plough [the common plough] has just made; and, without turning up the substratum, penetrates into and loosens from 8 to 12 inches deeper than the plough has before gone; which operation, besides draining the land, causes the water to carry along with it any vitriolic or other noxious matter by the substratum thus loosened. The roots of plants may penetrate deeper; and, in course of time, that which is but a barren substance, may become fertile soil." This is truly the subsoil plough of Mr Smith, invented, laid aside, and forgotten for a period of 35 years.

(1214.) Recent experience points out the reason why the earlier introduction of the subsoil plough did not meet with the success which has attended Mr Smith's, which, from the above description, appears to be the same implement, for they appear in the essential parts to be almost exactly alike; yet the one has been lost sight of, while the other has come into all that notice which it deserves. The reason is now obvious: Without the necessary improvement of thoroughdraining, subsoil ploughing is thrown away; and though thorough, or at least furrow, draining, has been practised in England for a long period,* the idea of combining the two seems not to have occurred to the agriculturists of that day. To Mr Smith, therefore, is still due the merit of having brought these two powerful auxiliaries of agriculture into effective co-operation.

(1215.) Since its first appearance in 1829, Mr Smith's plough has undergone various slight alterations, not affecting, however, its essential character, but chiefly in lightening its construction. The implement at first was made of enormous weight, sometimes so much as 5 cwt., but a few years' experience served to show that all its objects could be achieved with a plough of little more than half that weight; they are accordingly now generally made from 2 to 3 cwt. Fig. 207 represents one of the modifications of the subsoil plough as now manufactured by James Slight & Co., Edinburgh. It retains all the acting parts of Mr

Fig. 207.

b

k

p

THE DEANSTON SUBSOIL PLOUGH.

Smith's without material change, except in weight, though in other respects it deviates slightly from the original. The beam, which is from 3 to 34 inches deep at the fore sheath or slot, a, and 1 to 14 inches thick, extends from b to c, a length of 7 feet 4 inches; at c, the point, it is diminished to 2 by inches, and at b to about the same dimensions. The two handles, extending from d to

* See Sir James Graham's observations on the subject in vol. i. p. 30 of the Journal of the Royal Agricultural Society of England.

e, are 6 feet 9 inches in length. They are thinned off at e, and bolted, one on each side, to the beam; the depth of the handles is 2 to 24 inches, and are 3 toinch thick, worked into sockets at d in the usual manner for the reception of a wooden helve. The beam and handles are further connected by stretchertubes and bolts, the latter passing through all three at b, and binding them firmly together; the handles are also further supported by the stretcher-bolts and bow, ƒ and g. The beam is mounted at e with the bridle, which is at least 2 inches by inch, bolted on the point of the beam, being first formed into an oblong loop of 8 inches in length, standing at right angles to the beam, and having the opening vertical. To the front part of the loop is fitted a stout clasp, the two arms of which embrace the loop above and below, and admit of the slot hh to pass at once through them and the loop. The clasp and slot together have a motion along the loop right and left, and the slot itself has a motion vertically. The chain-bar, i, is attached to the beam at k, and passes through an eye in the lower end of the slot h; to the chain-bar is then attached the draught hook 1, to which the yoke is applied. The motion above described of the slot h, and consequently of the chain-bar and draught hook, afford ready means of adjusting the earthing and landing of the plough, and the position is retained by means of the pinching screw m, which, by being screwed into the clasp, acts against the outside of the loop, drawing the slot and the loop into firm contact. The body consists of the two slots a and n, the first about 3 inches broad, the last about 24 inches, and each inch thick; they are welded to a sole bar 2 inches square, and 30 inches long, flush on the land side. The head of the slots is worked into a kneed palm, which is strongly bolted to the beam, and the diagonal brace o, is fitted in to resist the strain that tends to derange the form of the body. The coulter-bar p is 3 inches broad, inch thick at the back in the upper parts, becoming thinner downwards, and is finished with a blunt edge and point; it is simply held in its place by being tongued into the beam, the fore slot, and the share. The share q is made after the same form as that of the common plough, having a feather to the furrow side, and is spear pointed. The length of the share is from 14 to 16 inches, and the breadth over the feather about 6 inches. It is fitted upon the prolongation of the sole bar, and its socket is usually furnished with a short ear, by which it is fixed to the sole bar to prevent its falling off, as the fixture of the coulter depends upon the share keeping its place. The feather r is a thin edged bar, 3 inches deep and about 1⁄2 inch thick, thinned off on the upper edge; it is tapered off at the fore end where it joins the share, and is held in contact by being notched into it; but its chief supports are two palms, by which it is bolted to the sole bar; and a sole shoe of cast iron, having a flange rising 6 inches on the land side, completes the subsoil plough, which, with the exception of the sole shoe, is constructed entirely of malleable iron. The length of the plough over all is about 13 feet; the length of the sole 3 feet 3 inches; the height of the handles 3 feet 6 inches; and at the point of the beam 2 feet 4 inches.-J. S.]

(1216.) [Not much need be said regarding the efficacy of subsoil-ploughing. After what I have stated of the immense value of a mixture of impalpable matter, and larger particles, in the form of a porous mass, I need scarcely say, that anything capable of increasing the depth to which this porosity extends, must of necessity be advantageous. This, however, does not shew any difference betwen sub-soil and trench-ploughing-in my opinion, the latter is the best in most instances, and this for the following reasons. All subsoils re

quire ameliorating by exposure to air, before they are capable of acting beneficially to plants-this is owing to certain chemical changes which are produced by the joint action of air and water, and it is very evident that all these must take place much more rapidly, when the subsoil, as in trench-ploughing, is laid upon the surface of the field, and freely exposed throughout the winter, than when the air is merely admitted more freely by the subsoil being broken up while it still remains under the surface. It may be averred that the trenchplough does not go so deep into the soil as the subsoil-plough, but still I cannot help thinking that notwithstanding this disadvantage (if any such exists), it is in most cases the most advisable of the two methods, if employed for deepening the soil. Not so, however, if used to assist in draining the subsoil. To prove its value for this purpose, I would earnestly direct your attention to the following valuable remarks of Professor Johnston:-" The subsoil plough is an auxiliary to the drain-in very stiff clay subsoils it is most advantageous in loosening the under layers of clay, and allowing the water to find a ready escape downwards, and to either side until it reach the drains. It is well known that if a piece of stiff clay be cut into the shape of a brick, and then allowed to dry, it will contract and harden-cut up while wet, it will only be divided into so many pieces, each of which will harden when dry, or the whole of which will again attach themselves, and stick together if exposed to pressure. But tear it asunder when dry, and it will fall into many pieces, will more or less crumble, and will readily admit the air into its inner parts. So it is with a clay subsoil. After the land is provided with drains, the subsoil being very retentive, the subsoilplough is used to open it up-to let out the water, and to let in the air. If this is not done, the stiff under-clay will contract and bake as it dries, but it will neither sufficiently admit the air"-nor let out the water- nor open a free passage for the roots. But let this operation be performed when the clay is still too wet, a good effect will follow in the first instance; but after a while the cut clay will again cohere, and the farmer will pronounce subsoiling to be a useless expense upon his land. Defer the use of the subsoil-plough till the clay is dry-it will then tear and break instead of cutting, and the openness will remain. Once give the air free access, and it, after a time, so modifies the drained clay, that it has no longer an equal tendency to cohere. Mr Smith of Deanston very judicially recommends that the subsoil-plough should never be used till at least a year after the land has been thoroughly drained. To attain those benefits which attend the adoption of improved methods of culture,

. let the practical man make his trial in the ways and with the precautions recommended by the author of the method, before he pronounce its condemnation." Thus you perceive that subsoil-ploughing when properly performed, will always be found useful in assisting the action of drains, but cannot be considered equal to deep or trench-ploughing, if an alteration is desired in the depth of the soil.

(1217.) Another alleged advantage of subsoiling is the breaking in pieces the moor-band pan. I will therefore now say a few words respecting this enemy to good farmers. This ferruginous deposite which so frequently occurs in particular localities between the soil and subsoil is extremely hard and compact, and almost completely impermeable to water. Very much has been written concerning this substance, by persons who have but little knowledge of chemistry,

Johnston's Elements of Agricultural Chemistry, p. 126.

and in their endeavours to prove the manner in which the deposite had been produced, and likewise the cause of its injurious action upon vegetation when newly brought to the surface, have made so many chemical errors, that the whole subject appears at first sight wrapped in doubt, whereas, we believe, that for all practical purposes its nature is already sufficiently well known.

(1218.) Moor-band pan belongs to a class of bodies known to chemists under the name of ochrey deposites. These deposites, which so frequently occur in the beds of chalybeate springs, were carefully examined by Berzelius in 1832; and were found to consist of the two oxides of iron in chemical combination with two new organic acids, which he denominated the crenic and apocrenic acids. Feeling certain from various circumstances, that moor-band pan belonged to this class, I undertook an analysis to ascertain whether it contained these acids, and find that in each of two specimens of pan, sent to me for the purpose, there exists a large proportion of crenic acid, in one apocrenic also, and in the other humic acid; there can therefore be no longer any doubt about the composition of this substance: and, instead of attempting to prove its injurious effects by relating the difference between the protoxide and peroxide of iron, and the fact of the peroxide being generally combined with water forming hydrate, none of which facts throw the least light upon the subject; we can readily explain all by reference to the chemical properties of the compounds of these two acids with iron. It is well known that iron in solution acts injuriously upon vegetation; and Berzelius has shewn, that the crenate and apocrenate of the protoxide of iron are both soluble in water; and that the same salts of the peroxide, although of themselves insoluble, are easily rendered so by ammonia, which substance is always produced in fertile soil; it follows, therefore, that moor-band pan must continue injurious to vegetation so long as the crenates and apocrenates of iron remain undecomposed. In the course of time, various chemical changes are effected by the joint action of air and moisture which decompose these compounds, and give rise to new ones having no injurious effect upon vegetation.-H. R. M.]

END OF VOLUME I.

PRINTED BY NEILL AND CO., OLD F13UMARKET, EDINBURGHL

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Scale of Feet.

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