b the point of the beam, c the position of the horse's shoulder, and a d the horizontal line; then will ca d be the angle of draught equal to 20°. Let the circle e represent a wheel placed under the beam, which is supported by a stem or sheers, here represented by the line e b. In this position, the point of the beam, which is also the point of draught, lies in the line of draught; the wheel, therefore, bears no load, but is simply in place, and has no effect on the draught: the motive force, therefore, continues to be 336 lb. Suppose now the point of the beam to be raised to g, so that the line of draught ge may be horizontal; and since the line of draught lies now out of the original line a bc, and has assumed

that of a gc-g being now supported on the produced stem c g of the wheeldraw gi perpendicular to a c, and complete the parallelogram aig k; the side a i will still represent the original motive force of 336 lb., but, by the change of direction of the line of draught, the required force will now be represented by the diagonal ag of the parallelogram, equal to about 351 lb.; and ge is a continuation of this force in a horizontal direction. The draught is therefore increased by 15 lb. Complete also the parallelogram a 1 g m, and as the diagonal a g—the line of draught last found-is equal to 351 lb., the side 1 g of the parallelogram will represent the vertical pressure of the beam upon the wheel e, equal to about 200 lb., which, from experiments (809), may be valued at 40 lb. of additional resistance, making the whole resistance to the motive force 391 lb., and being a total increase arising from the introduction of a wheel in this position, of 55 lbs. Having here derived a maximum,—no doubt an extreme case, and the usual angle of 20° as the minimum, we can predicate that, at any angle intermediate to lab and lag, the resistance can never be reduced to the minimum of 336 lb. Hence, it follows, as a corollary, that wheels placed under the beam can never lessen the resistance of the plough; but, on the contrary, must, in all cases, increase the resistance to the motive force more or less, according to the degree of pressure that is brought upon the wheel, and this will be proportional to the sine of the angle in the resultant a g of the line of draught.

(811.) The application of a wheel in the heel of a plough, does not come under the same mode of reasoning as that under the beam, the former becoming a part of the body, from which all the natural resistance flows; but in viewing it as a part of that body only, we can arrive at certain conclusions which are quite compatible with careful experiments.

(812.) The breadth of the whole rubbing surface in the body of a plough, when turning a furrow, is on an average about 17 inches, and supposing, that surface to be pressed nearly equal in all parts, we shall have the sole-shoe, which is about 2 inches broad, occupying part of the surface; and taking the entire average resistance of the plough's body, as before, at 336 lb., we have of this, equal to 48 lb., as the greatest amount of resistance produced by the sole of the plough. But this is under the supposition that the resistance arises from a uniform degree of friction spread over the whole rubbing surface of the body; while we have seen, on the contrary, that the coulter, when acting alone, presents a resistance equal to the entire plough. It is only reasonable, therefore, in absence of further experiments, to conclude, that the fore-parts of the body,— the coulter and share,-yield a large proportion of the resistance when turning the furrow slice; but since we cannot appreciate this with any degree of exactness, let the sole have its full share of the resistance before stated, namely, 48 lb. If a wheel is applied at or near the heel of the plough, it can only bear up the hind-part of the sole, and prevent its ordinary friction, which, at the very utmost, cannot be more than of the entire friction due to the entire sole. A wheel, therefore, placed here, and acting under every favouring circumstance, even to the supposed extinction of its own friction, could not reduce the resistance by more than 24 lbs., being the half of that due to the entire sole, or it is of the entire resistance. But we cannot imagine a wheel so placed, to continue any length of time, without becoming clogged in all directions, thereby greatly increasing its own friction; and when it is considered that the necessarily small portion, of any wheel that can be so applied, will sink into the subsoil, to an extent that will still bring the sole of the plough into contact with the sole of the furrow. It will thus be found that the amount of reduction of the general resistance will be very much abridged, certainly not less than one-half, which reduces the whole saving of draught to a quantity not exceeding 12 lb., and even this will be always doubtful, from the difficulty of keeping such wheels in good working condition. This view of a wheel placed at the heel has been confirmed by actual experiments, carefully conducted, wherein Palmer's patent plough with a wheel in the heel (as patented many years ago), but in this case it was applied on the best principles, gave indications of increased resistance from the use of the wheel, as compared with the same plough when the wheel was removed; the difference having been 1 stone in favour of no wheel. I hesitate not, therefore, to say, that, in no case can wheels be of service towards reducing the resistance of the plough, whether they be placed before or behind, or in both positions, and the chances are numerous that they shall act injuriously. That the use of wheels may, under certain circumstances, bring the implement within the management of less skilful hands than is required for the swing plough, must be admitted; but, at the same time, there may be a question whether, even with that advantage, the practice is commendable. I should be wanting in candour if, for myself, I answered otherwise than in the negative.-J. S.]

26. OF THE VARIOUS MODES OF PLOUGHING RIDGES.

your ploughshare

Drawn by one pair, obedient to the voice,

And double rein, held by the ploughman's hand,

Moves right along, or winds as he directs.

GRAHAM.

(813.) Your knowledge of soils will become more accurate after you have seen them ploughed, for as long as a crop, or the remains of one, covers soils, their external characters cannot be fully exposed to view.

(814.) On observing a plough at work you might imagine that the laying over of a furrow-slice is a very simple process; but it is really not so simple as it appears. You have already seen, in the construction of the plough, that the furrow-slice is laid over by a machine of very complicated structure, though simple in its mechanical action on the soil; and you may learn, by a single trial, that the plough is not in reality so very easily guided as it appears to be in the hands of an expert ploughman. You might also imagine that as the plough can do nothing else but lay over a furrow-slice, that the forms of ploughing do not admit of much variety, but a short course of observation will convince you that there are many modes of ploughing land.

(815.) The several modes of ploughing land have received characteristic appellations, and these are, gathering-up; crown-and-furrow ploughing; casting or yoking or coupling ridges; casting ridges with gore furrows; cleaving down ridges; cleaving down ridges with or without gore furrows; ploughing two-out-and-two-in; ploughing in breaks; cross-furrowing; angle ploughing, ribbing, and drilling; and the preparative operation to all ploughing is termed feering or striking the ridges.

(816.) These various modes of ploughing are contrived to suit the nature of the soil and the season of the year. Heavy land requires more cautious ploughing than light, because of its being more easily injured by rain; and greater caution is required to plough all sorts of land in winter than in summer. The precautions here spoken of allude to the facilities given to surface water to flow away, The different seasons, no doubt, demand their respective kinds of ploughing; but some of the modes are common to all seasons and soils. Attention to all the methods will alone enable you to understand which kind is most suitable to particular circumstances of soil, and particular states of season. To give you an idea of all the modes, from the simplest to the most complicated,

let the ground be supposed to be even in reference to the state of its surface.

(817.) The supposed flat ground, after being subjected to the plough, is left in the form of ridges or of drills, each ridge occupying land of equal area, determined by similar lengths and breadths. The ridges are usually made N. and S. that the crop, as I before observed when speaking of enclosures (582), may enjoy the light and heat of the solar rays in an equal degree throughout the day, but they should, nevertheless, traverse the slope of the ground, whatever its aspect may be; and this is done that the surface water may flow easily away.

(818.) Ridges are made of the different breadths of 10, 12, 15, 16, and 18 feet, in different parts of the country. These various breadths are occasioned partly by the nature of the soil, and partly by local custom. With regard to the soil, heavy land is formed into narrow ridges, to allow the rain to flow quickly into the open furrows. Hence, in many parts of England, the ridges are only 10 and 12 feet in width, and in some localities they are in ridglets of 5 or 6 feet. In Scotland, even on the strongest land, the ridges are seldom less than 15 feet, in some localities they are from 16 to 36 feet, and in light soils a not unusual width is 18 feet. In Berwickshire and Roxburghshire, the ridges have for a long period been 15 feet on all classes of soils, being considered the most convenient width for the ordinary manual and implemental operations. In other parts of the country 16 and 18 feet are more common. More than half a century ago ridges were made very broad, that is, from 24 to 36 feet, high on the top or crown, and crooked like the letter S., from the mistaken notion that the crook always presented some part of the ridge in a right position to the sun, a form which, although it did, would remove other parts as far away from the sun's influence. In the Carse of Gowrie such broad crooked ridges still exist, but the usual practice throughout the country is to have ridges of moderate breadth, straight, and looking to noon-day. In many parts of Ireland the land is not put into ridges at all, being done up with the spade into narrow stripes called lazy-beds, separated by deep narrow trenches. Where the plough is used, however, ridges are always formed, though narrow, but usually of 12 feet. For the sake of uniformity of description, let it be understood, when I speak of a ridge, that an area of 15 feet of width is meant.

(819.) The first process in ridging up land from the flat surface is called feering or striking the ridges. This is done by planting 3 or more of such poles, graduated into feet and half-feet, as were recommended for setting off the lines of fence (604), and which are used both for directing the plough employed to feer in straight lines, and for measuring

G g

off the breadth of the ridges into which the land is to be made up, from one side of the field to the other.

(820.) Land is feered for ridging in this way. Let a b, fig. 132, represent the S. and E. fences of a field, of which let z be the headridge or headland, of the same width as that of the ridges, namely 15 feet.

Do the same along the other

Then take a pole and mea

To mark off its width distinctly let the plough pass in the direction of re, with the furrow-slice lying towards x. head-land, at the opposite end of the field. sure off the width of a quarter of a ridge, viz., 3 feet 9 inches, from the ditch lip a to c, and plant a pole at c. With another pole set off the same distance from the ditch a to d, and plant it there. Then measure the same distance from the ditch at e to ƒ, and at ƒ look if d has been placed in the line of fc, if not, shift the poles a little until they are all in a line. Make a mark on the ground with the foot, or set up the plough-staff, at f. Then plant a pole at g in the line of fd c. Before starting to feer, the ploughman measures off 14 ridge, namely, 18 feet 9 inches, from ƒ to k, and plants a pole at k. He then starts with the plough from ƒ to d, where he stops with the pole standing between the horses' heads, or else pushed over by the tying of the horses. He then, with it, measures off, at right angles to fc, a line equal to the breadth