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RI is a piece fitted between the two uprights, and capable TU of being fixed at any height by pins passing through holes in the uprights. The plough is attached to the TS. carriage by a strong iron link, which passes round the beam near the middle of its length, and also by a chain on the top of the beam, which is fastened to the top of the carriage. The draft is taken from a rack fixed in front of the axletree, which admits of regulating the point of draft, sideways.

The improved Norfolk plough is shown at the bottom of the same plate, in a view from the land side, but all the other ploughs are viewed from the furrow side. This plough is very similar to its original, but it is put together in a better manner, by the assistance of iron work. The share is united to the beam by a plate of cast iron; and the coulter is wedged into an iron socket at the side of the beam, without weakening the beam by a mortise. At the top of the uprights of the carriage are eyes to conduct the reins by which the ploughman guides his horses.

The Kentish turn-wrest plough, or right and lefthanded plough, is sometimes made with wheels and a carriage, like the Norfolk plough, but in a smaller and more compact form; and at others, with only a foot or supporting iron in front. The beam is straight, very long, and thick. The peculiarity of this plough is, that it can be made to throw the sod to either side; whereas the common ploughs uniformly turn over the furrow to the right-hand side of the plough. The share is very long, and taper in thickness; but its horizontal width is the same at the point as at the heel. Instead of a mould-board, a clumsy log of wood is affixed to the share, by a hook at the fore end, and is held at a given degree of obliquity, by an iron brace or stay, which is only fixed by hooking it into its place. This piece of wood forms the wedge which is to remove and turn the soil, which the coulter and share have cut up. It can readily be removed from the plough and fixed on either side; and it will throw the sod over on that side where it is fixed, because the share itself is parallel, and does not form part of the wedge. The share is usually square at the end, with a cutting edge like a chissel, from four to seven inches wide. As the coulter must always be in the line of that side of the share which is to go against the solid land, it is fitted into a mortise in the beam, with as much play as is necessary to incline its point to the right or left, and make it line with either side of the share. A strong wooden lever is also made to act upon that part of the coulter which projects through the mortise above the beam, by which the coulter can be forced to either side at pleasure, and retained where it is placed.

A turn-wrest plough is very useful for working on the side of steep hills, or in a diagonal direction where the sod or furrow-slice may be turned to the lower side. The turn-wrest plough used in Scotland is described by Mr. Andrew Gray in the Engravings of Scotch Implements, published by the Board of Agriculture.

Ducket's skim-coulter plough, is a swing plough, with a small cutter or share, called a skim, affixed to the coulter, and projecting on one side, in order to skim the surface; that is, to pare off a thin turf. The skim is made of iron plate, sharp at the most advanced edge, and bent so as to turn the turf sideways, and throw it into the bottom of the preceding furrow. The

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share and mould-board of the plough, which follow the skim, cut up a large sod and turn it over upon the CULTU turf, so as to bury it. The only differences between this and the common plough is, that the coulter is advanced farther before the share, because, in the common position for the coulter, it would choak when in work. When the skim coulter is removed and a common coulter applied, the plough is used for common work. Sometimes the skim coulter is applied to a common plough, before the common coulter: in that case the skim coulter does not cut into the ground any deeper than is necessary to remove the superficial turf. The paring plough (see plate II.) is a swing plough, Paring with a wide share, adapted to cut up a thin sod plough. or turf from the surface, in order to burn it, for the improvement of the land; an operation which is very extensively practised in some districts. The figure shows, that the cutting edge of the share is very wide, and the mould-board has less curvature than some other ploughs. Instead of a coulter, a circular plate of iron is employed, steeled on the edge and made sharp, so as to cut into the turf to the requisite depth. This is called a scaife, or wheel coulter, on account of its revolving motion; it makes less resistance than a common fixed coulter; but it could not be used to cut to the depth necessary for common ploughing. This is often called the Lincolnshire plough (being much used in that county, the isle of Ely, Cambridgeshire, &c.) but more usually, the horse paring-plough, to distinguish it from the breast-plough, which is a simple implement, like a large shovel, with a sharp cutting edge in front, and worked by a man, who pushes it before him. For paring, the irons are kept very sharp with a file, and the plough is set to go keen; that is, the share is beaten thin, and set a little dipping; the foot adjusts the depth, and presses firmly on the ground: the circular blade of iron must also be kept very sharp, aud made to run very true, and very near to the share, where it divides the sod, as the share raises it from the land side. The sods thus turned over are from an inch to an inch and a half in thickness, and in a few days, in favourable weather, are dry enough to burn. The paring plough will not work on a hard surface.

Lord Somerville's patent double furrow plough, see plate H. has the beam curved, as the figure plainly shows, so that the line of the land side, of the most advanced share and coulter, is removed from the line of the other as much as the breadth of the furrow which is to be cut, by either of them; and the sod which the last share cuts, is turned over into the furrow opened by the first share. The coulters of this plough are braced by oblique irons, which makes them very strong, and they are double edged; the extreme part of the mould-board is moveable, and its obliquity can be increased or diminished at pleasure to turn over the sod in a greater or less degree as the farmer may require. His lordship's patent was principally for this improvement, which he also applied to a very useful swing plough which bears his name; but which is, in other respects, very much like Small's plough.

Ducket's trenching plough, and Bemman's patent plough, are double ploughs, but both shares follow in the same line, and plough at two depths.

Three, four, and five-furrow ploughs are very numerous among agricultural speculations, but as we do

The binot.

Structure of ploughs.

Vomis, et inflexi primum grave robur aratri.” and is given in this work as affording some proof of what is supposed to be the case with the first ploughs, namely, that they were constructed to tear up the soil, but were not adapted to turn it over. An implement of a similar description has been lately proposed for breaking up old roads or stony foundations, and might perhaps be used to plough with advantage on some heavy soils, when the lands get too hard before the fallows can be broken up. On this subject the reader will find more under the head FALLOWING, in the article AGRI

CULTURE.

The binot is a better implement for the purpose above contemplated. Sir John Sinclair, in "The Husbandry of the Netherlands," has described this implement, which, from the nature of its action, comes nearest to the Roman plough; and for utility and convenience is infinitely superior to it. The beam is supported at the fore-end by two wheels, with an axletree and pole for the horses to draw by, similar to the fore-wheels of a waggon on a small scale: there is no coulter, and there are two mould-boards, one on each side of the beam; but these are not like the mould-boards of other ploughs, being only inclined planes, forming a continuation of the wedge of the share the whole implement is a wedge, which is drawn through the ground and makes a cut or fissure, raising the earth on each side in small ridges. There is one handle or lever behind for the purpose of guiding the plough, and in the front a staff is raised up to conduct the reins by which the ploughman can guide the horses. This implement has been considerably improved in England.

The double-breasted or double mould-board plough is very similar to the binot in its manner of action, but is made in a lighter manner, and on a more simple construction. The miner is very similar to the binot.

On the structure of ploughs. From the above sketch of the different kinds of ploughs, our readers may gain a general idea of their construction; and we must now enter somewhat more fully into the best proportions of some one kind of plough, from which rules may be laid down generally applicable to the rest.

The chief requisites of a good plough are, that it should easily penetrate the earth, cutting both vertically and horizontally, with the least possible expence of labour, and that it should afterwards raise the sod so cut from its primitive bed, to an angle gradually ascending from the advanced point of the share, along the mould-board, or furrow side of the plough, till the earth reaches a proper elevation. When turning over to its new place of rest, its descent also should be so influenced, by the form of the plough, as to make it fall gradually, and in such a manner, that it shall disturb as little as possible the motion of the hinder parts

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of the implement. The chief object in ploughing is to AGRI expose the greatest surface of earth to the influence of CULTU the sun and atmosphere, and to furuish the greatest quantity of mould for covering the seed. And it is evi- MENT dent from the property of right-angled triangles, that the furrow whose depth is about two-thirds of its width, and laid to make an angle of 45 degrees with the horizon, will expose the greatest surface possible, and produce the greatest quantity of mould. The position in which the sod will lie, when cut and turned over, depends on the proportion between the breadth and depth of the furrow, and not on the form of the mould-board; because every sod when turned over, bears against the sod preceding it. sod preceding it. Hence it appears that the position of the sod depends very much on the judgment of the ploughman, in properly proportioning the breadth and depth of the furrow.

Plate IV. Fig. 1, AGRICULTURAL IMPLEMENTS, is a Plate IV. section of a ridge or land twelve feet wide, properly Section ploughed in furrows, each of which is nine inches wide, ridge. and four inches and a half deep. Here it is evident that not only the surface is increased, but also the depth of the staple, which greatly extends the pasture of plants.

A fundamental maxim in the construction of ploughs is, that the land side, as well as the sole, must present plane surfaces, intersecting each other at right angles; for the share is a sharpened wedge, which is forcibly introduced between the sod and the solid land, the resistance which the sod makes must, therefore, be counteracted by the solid land, which forms a rectangular trough, or furrow, against which the land side and sole of the plough bear. The furrow is a straight and firm groove, into the angle of which the plough is strongly pressed, and its progressive motion is thus directed. The straightness of the course which the plough will follow, depends very much on the straightness of the sole and land side, in the same manner as the direct progression of a ship depends on the keel. It is true, that in either case the steersman may correct any tendency to deviate, but it must always be at the expence of the impelling force. The furrow side of the plough, and mould-board, should be formed to one regular twist from the point of the share to the extremity of the board. As the operations of raising, shifting, turning over, and placing the earth or sod in a proper position, with the least friction, depend in a great measure on the shape of the mould-board, it must be of importance to have a certain rule or method by which its surface may be formed agreeably to any given principle. The mould-board is the most delicate part of the plough, and is to be found in the greatest variety in the works of different artists, each of whom has a nostrum of great value in his own opinion. It would much exceed our limits to give rules upon this subject, as they can hardly be briefly expressed without numerous figures, but we will suggest a few observations: the task to be performed by the mould-board is, to raise, push aside, and turn over to a certain degree, a slice already cut off from the firm ground. Mr. Small's maximum was, that as the plough advances through equal spaces, the twist and the lateral sliding of the sod should increase by equal degrees; and this determines, à priori, the form of the mould-board. To construct it, the line called the wrest must be divided into equal parts; this line is the edge or boundary of the flat sole on the furrow side of the

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GRI plough; it is a straight line, and is usually inclined to ULTU the land side of the plough, in an oblique angle; so RAL that if the plough be turned upside downwards, the flat sole, which applies to the bottom of the furrow, is of a triangular shape. Having divided the wrest into equal parts, then the angle which the surface of the mould-board makes with the flat surface of the sole at each of these divisions must increase by a regular progression. The rules for constructing this kind of mould-board, which are laid down by Mr. Small, in his treatise before alluded to, are not mathematically exact, but his suggestions are adapted to the capacity of those for whom they are intended, and approximate very nearly to the truth of the subject. Small's ploughs have been found to answer extremely well, in a long course of practice.

Mr. William Amos published a paper in the commuplough, nications to the Board of Agriculture, on the mathematical construction of a plough, with rules for workmen. He considers a mould-board as composed of two inclined planes, one acting in a perpendicular direction, to raise the furrow; the other in an horizontal direction, to turn it over. Upon the proper form of the curve, which a combination of these inclined planes ought to make, the perfection of a plough depends, as the chief resistances are there met with, and must be

overcome.

Jeffer Mr. Jefferson, late President of the United States in America, has given a paper on the construction of a plough and mould-board, which was published in 1802, and is reprinted in the Philosophical Magazine for 1805, vol. xxii. His principle is nearly the same as that followed by Mr. Amos.

Bailey. Mr. John Bailey has given a very excellent paper on the true principles for a plough, in his Essay on the Construction of the Plough, and in his Report on the Agriculture of Durham. In some points he follows Mr. Amos, but his rules for the mould-board are more correct in principle. He states, that for a small slice, or section, an inclined plane may be so twisted as to raise any thin and flexible sod from an horizontal position to a perpendicular one, in which the only resistance to be overcome, arises from the weight of the earth. This will not do so well for the whole sod of old sward, which being bound together throughout by fibrous roots, of different textures, they create an elasticity which affects the whole, from the share point to the hind end of the mould-board.

To find, therefore, the proper curve in this case, a sod of this kind was turned over as if left by the plough, viz. in an horizontal position, at the place where the point of the share is supposed to be, and so twisted, that in the length of the required share, or mould-board, the sod should be turned over, and lie at an angle of 45 degrees; then the inner edge or surface of the sod forms a curve which the mould-board ought to fit so as to be pressed equally alike from one end to the other. Mr. Wm. Cooke obtained a patent in 1813, for improvements in making ploughs; his specification contains a new principle for setting out the curve of the mould-board. (See Repertory of Arts, vol. xxiv. Second Series.)

Mr. Robert Bemman likewise obtained a patent in 1815, for a new construction of the share and mouldboard, which we think is founded on a good principle. The first circumstance is, that the wrest of his plough

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is a straight line, and parallel to the land side of the AGRIplough, so that the sole of his plough is of a parallel CULTU width, and equal to the width of the furrow; the sole is IMPLEbounded in front by the oblique cutting edge of the share, MENTS. and on one side by the land side of the plough, and on the other side the wrest or lower edge of the mouldboard. The cutting edge of the share is therefore of such width, that the sod, or furrow slice, which is to be removed, will be completely cut or divided from the lower soil, by the oblique edge cutting horizontally under the whole width of the part to be removed, in the same manner as the coulter of the plough cuts, and separates the upright side of the said sod from the land; by this means, the sod is completely severed and cut up from the lower soil, before it is turned, making a flat bottom to the furrow, whereby roots and weeds of every description are cut through.

The mould-board, or plate of the plough, should be of such form, that it will turn over the sod by an uniform action with a kind of rolling motion, and without elevating or removing the sod sideways, any farther than is absolutely necessary to turn it over; but turning it upon one of its angles, as a centre of motion.

The particular construction of the share and mould- Plate IV. plate, to obtain these effects, is explained by figs. 2, 3, and 4, plate IV. and is adapted to cut a sod, of a depth equal to two-thirds of the width; fig. 5 represents the share in different positions from the point; a to L is a keen bevilled edge, which cuts up the sod; the line Lt is also a sharp edge, which is in the same flat surface with the sole or underside of the share; and the line of the edge is parallel to the land-side, or straight tail a S, which runs against the land; the breadth Lb being equal to the width of the furrow which the plough is intended to cut; the line d t is that, where the share joins upon the mould-board; and H is a projecting piece, which enters into a corresponding opening in the mould-board to unite them firmly. At K are two holes for the screws, to fasten the share to the iron stem C, which descends from the beam of the plough.

Fig. 2 and 3, show the curvature of the share and mould-board when put together; fig. 2 being an elevation of the furrow-side, and fig. 3 a view of it taken from the point of the share. The lower edge tu is straight, and in the plane of the sole or under surface of the share, and is parallel to the land side, being a continuation of the edge L, t, of the share; therefore, when the plough is in action, the line tu proceeds forwards in the direction of its length, the several lines marked in fig. 2,-1, 2, 3, 4, &c. represent straight lines, which may be drawn upon the surface of the mouldboard. These lines originate in the line tu, being arranged thereupon at equal distances of about two inches from each other; when viewed in the direction of fig. 2, these lines appear to be perpendicular, but each line is inclined at a different angle of inclination to the under surface of the sole, as is shown by the elevation fig. 3, in front, where u 1 shows the inclination of the line 1, and u 2 shows the inclination of the line 2, and so on of all the rest, till the line u 13, which is perpendicular. This arrangement of the lines, forms a regularly winding surface, as is expressed by the perspective view fig. 4; from the horizontal line of the cutting edge 1 L, to the vertical line u 13; the part i, 2, Lof the share being made as thin as is consistent with strength, cuts under the sod, as shown at 2 L,

2 G

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AGRI- fig. 6, and separates it from the under soil, as the share CULTU- advances; till the line 4 t comes beneath the sod, the inclination of its surface will turn the sod to the position MENTS. of 4 t, fig. 6; beyond this line, the same regular curvature is continued by the mould-board, which, at the Plate IV. line 7, inclines the sod as at 7, fig. 6, thence to the line u 13, where the sod is turned over one quarter, as at u 13, fig. 6. In all these positions it will be seen, that the lower outside angle of the sod has not changed its situation, but the sod turns upon that edge as a centre, because the lower edge of the mould-board tu, which is beneath the angle w of the sod, is a straight line, proceeding forwards in the direction of its length. After the perpendicular line u 13, the mould-board is curved by a different law, as it is intended to turn the sod over upon its upper outer edge y, fig. 6, as shown at x 16, till it arrives at the position of x 18. To form a curve which will produce this effect, an imaginary line, fig. 4, is assumed in the plane of the sole or lower surface of the share, in a direction parallel to the depth of the sod; from the point u a line is drawn to v, perpendicular to tu, and from this point divisions are made on the line v, at intervals of two inches, or equal to the distances between the lines 1, 2, 3, and fig. 2; and from these divisions lines are drawn, every one at a different angle of inclination, as is shown by the dotted lines atv, in the front elevation T, fig. 3. All the lines being of equal lengths, give a number of points to form the lower edge of the mould-board; and the curvature or winding of its surface is found, by making the lines 14x, 15x, 16x, 17 r, and 18 r, at right angles to the different lines rv, with which each respectively joins at the point : this causes the last line s to overhang or incline outwards sufficiently to leave the sods in the position of x 18, fig. 6. The depth of the furrow being about two-thirds of the width, the mould-board represented is adapted to cut a furrow of nine inches wide and six inches and a half deep; that being the greatest depth for such a width. If it is desired to cut a furrow of less depth and width, the dimensions of the mould-board must be proportionally altered; the breadth of the sole between the land side and the line tu (being in all cases equal to the width of the furrow or sod intended to be cut), and the distance between the parallel lines tu and the line v, is always to be taken equal to the depth of the said furrow or sod.

Form of the share.

It may be necessary to remark, that the surface of the mould-board, however obtained, if made of wood and intended to be covered with iron plate, must be sunk or cut away one eighth of an inch (the thickness of the iron), in order that the form may not be altered. But mould-boards of cast iron, from a model made on the above principles, are much preferable, not only on account of the greater certainty of the form, but also in respect to cheapness.

On the form of the share. The share must always be flat on the underside to correspond with the flat sole of the plough, and the land side must be a straight line in continuation of the land side of the plough, but the cutting point or edge admits of variation. The shares most commonly in use, are called the spear-pointed share and the feathered share. The spear-point is simply a sharp point like a spear; but the feather share has a projection towards the right hand side to form an oblique cutting edge, as is shown in all the drawings

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shares.

of plate II, and separately in fig. 7, plate IV. That AGRI. part of the share which is made hollow, in order to fix CULTU it on the end of the piece of wood which forms the sole of the plough, is not so wide as the feather; hence in MENTS moving forwards the share cuts a wider surface than the sole occupies at its most advanced part; but in the spear-pointed share the cutting edge does not occupy a greater breadth of the furrow than the sole does at the front; indeed the share forms a continuation of the sole, and terminates it with an advanced point. The difference between the action in the spear or a Spear at feathered share will best appear by comparing them feathered together. It is evident from the construction of the feathered share, that in stony land it must meet with greater resistance than the spear share by reason of its breadth. It is not so, however, in every case, for as the plough with the feathered share takes the sod off broader than that part of the share which is fixed to the sole, this plough must be easier drawn when the land is free of stones, than that with the spear share, because the firm earth which the spear share must leave to be raised by the lower edge of the mould-board is previously cut from its bed by the feathered share, and consequently raised up more easily. At the same time the feather should not have too great a breadth, but should be in proportion to that of the under side of the plough behind, and of the furrow, slice, or sod, cut off by the coulter. Its breadth also depends on the nature of the soil. As the sole of the plough is usually from eight to ten inches broad, the breadth of the feather should be between six and eight inches. It has been thought an improvement in the plough to make the feather the full breadth of the sole. But when the feather is about two inches narrower than the sod, then that part of the sod next the open furrow not being cut, is held fast until the land side of the sod is raised on the back of the share and fore part of the mould-board, and when the sod is raised nearly on its edge this corner will easily be broken by the mouldboard. The slice of earth in this case does not slide into the open furrow, but is regularly raised and turned over as the plough advances. The tearing up of this small corner gives very little resistance to the plough; and the resistance it occasions is perhaps less than if it were wholly cut by the feather, because a greater breadth of feather with the same length would present a more obtuse angle to cut the earth, by which the resistance must be increased. In lands abounding with tough roots or couch grass, or in fact any root that runs deeper than the plough penetrates, the broad feather seems to have the advantage, especially if the length of the feather be in proportion to its breadth; in general, this proportion ought to be as two to one: so that if the extreme point of the back end of the feather be six inches from the straight line, or land side of the share, then the whole length of the feather should at least be twelve inches. Its cutting edge will then form an angle of about twenty-eight degrees with its land side. If the feather is required to be seven inches broad, its length ought to be about fourteen inches, and so on in proportion; and in this form its edge will always cut nearly at the same angle.

Ransom's patent cast iron shares, 1803; the lower side of the share is hard, and the upper soft, so that the wearing of the soft iron keeps the edge sharp; they are very extensively used.