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known, if the disease do not spontaneonsly make its appearance, spare without any great force being applied by the ploughman who holds
no pains to produce it. So great is the prejudice in favour of Plica the stilts.
entertained by the lower order of Poles, who regard it as affording a The Hindu plough consists of a slight beam, often without any
certain security from all other sickness and misfortunes, that they will coulter, a narrow share, and a corresponding stilt. The whole is of
through their whole lives endure the inconvenience and misery of wood, slightly pointed with iron. It is so light that a man can readily
carrying about huge masses of filthy stinking hair many feet in length, carry it upon his shoulder. When it is at work it is usually drawn
rather than submit to the removal of it, which is necessary for their by a small buffalo, and sometimes by a man or a woman. This instru-
relief.

ment is intended merely to make a shallow furrow in a very light soil, The hair of persons affected with Plica Polonica has been carefully or in the mud produced by irrigation where rice is cultivated. It does examined under the microscope, and Günsberg and Von Walther have not act as our ploughs do, nor does it turn over a regular furrow, toth described the cells of fungi belonging to the genus Trichophyton. but it acts more like one of the tines, or teeth, of some of our more The parasite as described by Günsberg consists of articulated fila complicated instruments called cultivators or grubbers, with which the ments surrounded by innumerable spores of very minute size. The earth is stirred without being turned over. changes in the hair produced by this parasite consist in the thickening The Chinese plough resembles the Hindu in its simplicity. The of the root of the hair, a spindle-like enlargement of the longitudinal earth is turned over by holding the instrument obliquely, and much cylinder of the channel of the hair, through the constant piling up of depends on the art of the ploughman, in whose hands it is like a stout new masses of fungi in it, in the splitting and parting of single hair shovel pulled through the ground by a horse or an ox. The sole is not fibres, which gives at last to the hair the appearance of a brush, or of straight, but rounded, like the bottom of a boat. The work done by a hedgehog skin, at the point through which the spores of the fungus this instrument is not unlike the furrow drawn in the sand at the pass. The epithelium or cells of the hair are very much condensed, bottom of the sea when a ship drags her anchor. and the hair cylinder frequently altogether disappears. In the The ploughs in use in different countries in Europe underwent little adhesive mass are found a great many large epithelial cells with small change for many centuries; it is only lately that any attempt has been granular bodies, resembling the exudation corpuscles of inflammation. made to vary the old forms. Von Walther attempted to inoculate Plica Polonica, but did not The Roman plough, such as is described by Virgil in the Georgics' succeed.

(i. 174), is still used in many parts of France, under the name of Araire Herr von Studzienski, a Russian, has recently written on the Plica, Romain. It consists of a beam (temo), a body (buris), a share (romer), and endeavoured to show that it was only an intense form of the and a handle or stilt (stira). The office of the turn-furrow is pernatural condition of moulting. This view however is not supported formed by two pieces of wood about six inches long projecting obby the facts of the case, and no one can doubt its specially morbid liquely upwards, and very properly called teeth (dentalia) E F (Fig. 1). nature, after such researches as those of Von Walther and Günsberg. The sole of the plough A B has two pieces of wood cg and d u fixed to

The only treatment which is known to be constantly beneficial is it on each side, forming an acute angle with it, in which the teeth are
the removal of the hair, and strict cleanliness; other means must be inserted. This exactly answers the description of Virgil, “ Duplici
decided in each case by the general state of the patient's health. The aptantur dentalia dorso” (the teeth are fitted to the double back).
popular notion entertained in Poland, that dangerous diseases will
follow the cutting of the hair, is entirely without foundation.

Fig. 1. (Kuchenmeister on Animal and Vegetable, Parasites, translated by

2. Lankester, 1847.)

PLINTH. [Column]

PLOMBAGIN. A bitter non-azotised principle of unknown com-
position, contained in the root of the Plumbago europea. It crystallises
in orange-yellow needles of an astringent saccharine taste, volatilises
by heat without change, and is slightly soluble in cold water, more so
in hot, and readily so in alcohol and ether. Alkalies communicate to These teeth help to push aside the earth to the right and left, and the
the aqueous solution a fine cherry-red colour.

instrument resembles what is called a moulding plough, which is used PLOTTING. _[SURVEYING.]

in throwing the soil aside against young plants growing in rows, as PLOUGH. That the plough is an instrument of the highest turnips, potatoes, &c. A chain or pole connected with the end of the antiquity is apparent both from the oldest writings that we possess beam was hooked to the middle of the yoke on the neck of the oxen, and from the existing monuments of Egypt. We might exercise our and thus the plough went on making parallel furrows, so near to each imagination in supposing a probable origin of the plough in the branch other that the preceding furrow was partially filled with the earth which of a tree dragged along the ground, in which the stump of a smaller the dentalia pushed aside. The point was in the shape of the head of branch made furrows as it went on. It seems indeed probable that a lance. This plough might suffice in light mellow soils, which had some accidental circumstance first suggested this mode of stirring the been long in cultivation, and had more the texture of garden mould earth to prepare it for receiving the seed.

than of stubborn clay. The oldest forms of the plough of which we have any description in The small double mould-board plough, common in other parts of ancient authors, or which are represented on monuments and coins, France, is evidently taken from this. The teeth not being sufficiently are very simple : a mere wedge, with a crooked handle to guide it, and strong, a slanting board was substituted on each side, and wheels were a short beam by which it was drawn, form the whole instrument. The added, to diminish the labour of the ploughman. The stilt remained light Hindu plough, now in use in many parts of India, seems to differ the same at the place where it is attached to the plough, but higher up little from the old model.

it was divided into two, like a fork, for the convenience of holding it Before we enter into any details it may be as well that we describe with both hands. This plough acts exactly like the other, but it is the different essential parts of a plough, by the names which are usually stronger and better adapted for heavier land. Neither of them goes given to them.

much deeper than four or five inches, leaving shallow parallel ridges, The body of the plough is that part to which all the other parts are in which the seed falls, and is buried by light wooden harrows, which attached. The bottom of it is called the sole, or slade, to the fore part are drawn over the land after sowing: This is an imperfect tillage, of which is affixed the point, or share; the hind part of the sole is the bottoms of the furrows being only partially stirred. The broad called the heel. The beam, which advances forward from the body, flat share, and the single mould-board which turns the earth com; serves to keep the plough in its proper direction, and to the end of it pletely over, after lifting it up, is a far more effectual instrument, and are attached the oxen or horses which are employed to draw it. Fixed has been adopted wherever agriculture has made any improvement. in the beam, in a vertical position, before the point of the share, with This plough more nearly imitates the digging with a spade; and the its point a little forward, is the coulter, which serves to cut a vertical more perfect the imitations, the better is the work. section in the ground, while the point of the share, expanding into a The mould-board of a modern plough is either fixed on one side, or fin, separates a slice by a horizontal cut from the subsoil or solid ground made so as to be shifted from one side to the other. In the first case half under it. The mould-board or turn-furrow, is placed obliquely behind the furrow-slices lie on one side and half on the other, and there is of the fin, to the right or left, in order to push aside and turn over the necessity a double furrow where they join. When it is desirable that slice of earth which the coulter and share have cut off': it thus leaves the surface should be quite flat, and the furrow-slices all in one direca regular furrow wherever the plough has passed, which furrow is tion, the mould-board must be shifted at every turn, and a plough intended to be filled up by the slice cut off from the land by the side which admits of this is called a turn-wrest plough. of it, when the plough returns. The stilts or handles, of which there It is evident that the mould-board of a turn-wrest plough must be so may be either one or two, as is thought more convenient, direct the constructed as to act with either side uppermost; it can therefore have plough by keeping it in the line required and at a regular depth in the only a very slight convexity to push over the slice cut off by the coulter ground. The single stilt appears to be the most ancient form. and share; and a considerable force is lost by the obliquity of the

Wheels are a modern invention in comparison with the other parts. action in doing so. The share of this plough is pointed like a lance, or They support the end of the beam, and prevent it from going too deep presents a flat edge like a broad chisel, according as the soil is light or into the ground while the plough is going on. The greatest improve heavy. The point of the coulter is placed in line with that side of ments introduced into modern ploughs are in the shape of the mould- the point which is nearest to the unploughed land, and this is done by board, or turn-furrow, of which we shall take particular notice, and means of a piece of wood A B (Fig. 21, which presses it against one side the contrivances for regulating the line of draught, so as to make the or the other of the mortice in which it is placed in the beam CD, by plough go at an equal depth, and cut off a regular slice of equal breadth, changing the position of the pieces A B to the other side of the projec

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the most regular furrows for the reception of the seed, which the ally required to prevent stones or other obstacles from turning the harrow can then most readily bury.

plough out of its course, two stilts are most convenient, placed at a The surface of this turn-furrow is curved in the form of the spiral more obtuse angle with the sole of the plough. thread of a screw, such as would be generated by a line (up in the The force required to draw a plough depends not only on the nature following figure) about 9 or 10 inches long, and either straight or of the soil, but also on the shape of the plough, and especially on the slightly curved, moved uniformly forward in a direction at right angles position of its different parts with respect to each other, so that they to its length, while it revolved uniformly round one of its extremities do not counteract each other. for 3 or 4 feet, commencing with the horizontal position, and terminating If a plough were drawn in the direction of the sole, the obliquity of in an angle about 45° beyond the vertical. The curve thus generated the turn-furrow would cause it to turn towards one side, and it would will be found to turn over soils of a moderate tenacity very perfectly. require a considerable force to keep it straight. In order to prevent If it is very light, the surface may be formed by arcs of circles with a this, the line

of draught is placed at an angle, which varies with that considerable diameter, the concave part upwards; if It is very tenacious, of the turn-furrow and the force required to push the furrow-slice over, the convex part of the arches may be upwards. The annexed figures To adjust this angle, so as to cause the plough to keep in the intended (6, 7, 8, 9) will explain this. The distance of the perpendicular line, there is a contrivance at the end of the beam to change the FG from the fin of the share may also be varied, either lengthening or position of the ring by which the plough is drawn to the right or left shortening the turn-furrow, as experience may show to be most of the line of the beam, and another by which it may be raised or advantageous.

lowered. By this device the plough may be drawn from a point on Horizontal Plan of the Plough.

either side of the beam, and higher or lower as may be required.

When the plough is found to take too much land, as ploughmen say, Fig. 6.

that is, tends to increase the width of the slice cut off by the coulter, the bridle is shifted to the left by moving the pin into another hole : when it goes out of the land, as it is called,

that is, diminishes the width of the furrow-slice, the pin is moved a hole or two to the right, until the plough has no tendency to deviate to either side. If it inclines to rise out of the ground, the ring is shifted in the iron bridle and placed in a hook or notch higher up; if, on the contrary, it dips too deep, the ring is hooked lower. Thus a plough may be made to go straight and at a regular depth, without any more force being applied to the stilts

than is required to counteract inequalities in the land, or accidental A B, the Sole ; c, the Fin; p c, the bottom of the Turn-Furrow; E c and I d being obstacles, such as stones or roots, which might throw the plough out

the revolving line traversing the distance c 1, and shown in its various of the ground. When the soil is of unequal texture, it is useful to positions by the transverse lines.

have a small wheel connected with the fore part of the beam, so as to Sections of. the three different turn-furrous at different

prevent its dipping downwards, which would require a great pressure

on the stilts to keep the point of the share up, and thus increase the distances from the heel.

friction of the sole on the ground, and consequently the labour of the Fig. 7.

Fig. 8.

horses. In other cases, ploughs are provided with two wheels connected with the beam, one of which runs in the furrow to the right, and the other on the unploughed soil to the left. When the plough has been well adjusted, and the larger wheel runs in the angle of the furrow, it acts as a gauge to regulate the width of the slice as well as its depth : in very uniform soils without stones, the plough, when set in the proper direction, will make a very straight and even furrow parallel to the one in which the wheel runs, without any person holding

the stilts ; so that all that is required is to turn the plough at the end Fig. 9.

of each furrow, and set it in to the proper line to form the next. As this admits of very correct adjustment, no unnecessary force is required to draw the plough : and hence this plough appears to be the easiest for the horses; and if the wheels are not very heavy, and the plough is of a good form, it certainly requires less power to move it than many which are without wheels; and it is far superior to the old clumsy wheel-plough, the beam of which rests on a heavy carriage,

without being firmly attached to it. This, instead of lessening the A plough was constructed on this principle by Messrs. Ransome, of draught, increases it by all the pressure of the beam upon the carriage, Ipswich, at the suggestion of the writer of this article (the late Rev. besides the weight of this last and of the wheels. There are some very W. Rham),

and exhibited at the meeting of the Royal Agricultural irregular and stony soils, where a common swing plough can scarcely Society of England, held at Cambridge, July 15, 1840. In soils of a loose mellow nature it answered completely, and did the work more

be kept steady without the help of wheels, and where it would not be

so convenient to have the beam fixed on the wheels. In this case a perfectly than any other plough. It united the parallelism of the sole separate carriage is necessary, that the ploughman may have a fulcrum and bottom of the turn-furrow of the Flemish plough with the im- on which he can raise his plough, or turn it to either side to avoid any proved shape of the turn-furtow. By adopting the variations in the considerable stone or other obstacle. Wheels have this advantage : shape of the turn-furrow which we have suggested, this plough may be they will enable an inferior ploughman to make better work than he adapted to any soil, and be used with or without wheels.

could possibly do without them; and that too with less labour to the Ploughs were formerly made of wood having those parts covered horses; because, from his want of skill, the swing-plough would be with iron where the greatest friction takes place, the share and coulter continually subject to sudden deviations, requiring him to use his only being of iron; but in consequence of the greater facility of strength to counteract them; and each exertion of the ploughman casting iron in modern times, it is now made wholly of this metal. adds to the labour of the horses. The advantages of iron are, its durability, and the smaller friction it occasions when once polished by use.

Without entering into any comparison of ploughs differently con

The inconveniences are, the structed, it is evident that the shape of the plough must vary with the additional weight of the instrument, and consequent greater friction nature of the soil which it is to turn up. A light soil must be shovelled of the sole, which experiments have proved to be greater than was up; a mellow one may be turned over with any kind of mould-board ; generally suspected. A great improvement has been introduced by a very stiff tenacious soil which adheres to any surface pressed against making the points of the shares of cast-iron, which, by a mode of casting it, will be more easily turned over by a few points of contact which do the lower surface on a plate of metal, makes one surface much harder not allow of adhesion. Hence the point and turn-furrow have been than the other; and as the softer surface wears more rapidly, a sharp made of all imaginable shapes, and while one man contends for a very edge is always preserved.

concave form, another will admit of nothing which is not very convex. The different parts of a plough are now usually cast, so that if any That plough will no doubt have the least draught which is best suited one fails or wears out, it can be instantly replaced by moving a few to the soil which it has to move. The lighter the plough is, conscrews or bolts. This is a very great saving of time and expense.; for sistently with sufficient strength, the less draught it requires, all other before this, every time an accident happened to any part of the plough, circumstances remaining the same. Lightness and strength combined it took a long time to repair it, and in the meantime the labour was suspended, often at a very critical time of the year. There is another work as well as a heavier, there can be no doubt that it is preferable.

are consequently great advantages, and if á very light plough does its advantage in having the essential parts of cast-iron. If any particular Durability is nothing compared with the saving of one horse in three: shape has been once discovered to be the best for any part, that shape it is cheaper to have a new plough every year than to keep an is preserved without deviation in every plough made on the same additional horse all the year. If a wooden plough is found to be more pattern, and with respect to the turn-furrow this is of the greatest easily moved than an iron one, there can be no doubt which should be importance. Where the soil is light and crumbling, without stones, as in Norfolk,

preferred. a single handle or stilt is sufficient; but where some force is occasion. I and coulter only are of iron, besides a thin sheet of iron over the mould.

The Flemish plough is made of wood, and is very light; the share

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board, which is shaped as if it had been rolled obliquely over a being quite covered by the two last. This now forms the crown of the cylinder, a shape well adapted to sandy soils. In ploughing land which ridge; and the succeeding slices are laid obliquely, leaning to the right is more or less mellow and crumbling, the great object is to bring to

Fig. 11. the surface that portion which has lain buried, and has not served to nourish the preceding crop, and to bury that which has produced vegetation, and in which the roots of various weeds have established themselves. When manure is to be covered with a certain depth of earth, a more complete subversion is required, in order that no part of it may remain uncovered. When the land is in a compact state, from the roots which pervade it, and it is only ploughed once to prepare it and left till the required width is obtained. Another land is now for receiving the seed, much greater nicety is required to lay the slices begun at the distance of a quarter of a perch from the last furrow, and at a certain angle so as to leave regular lines or depressions in which the seed may fall and be readily covered by the harrows which follow.

Fig. 12. In this case the angle of 45° is found to be the most convenient at which the furrow-slices may be laid against one another. The field will then have the appearance of being laid in small ridges as in the annexed figure, all towards the same side if ploughed with a turn-wrest Fig. 10.

laid exactly in the same manner. When the two lands meet, the intervening furrow, which had been purposely left shallower, is deepened; and there is a furrow between every two lands, the bottom of which is considerably below the bottom of the other furrows. When this field is ploughed again after harvest, the work is reversed; the furrow

between the lands is filled with the first slice, and another is placed plough, or towards a middle line if a plough with a fixed turn-furrow over this, which now becomes the crown of the land to be formed : has been used. To produce this regularity, the end of the turn-furrow this is called ploughing crown and furrow. When the lands are is made to press on the slice turned over. And if the mould-board be ploughed towards the crown, it is called gathering. By gathering convex, as it is in most Scotch ploughs, and in those made by Hornsby several times in succession, the soil is much raised at the crown at the of Grantham, this pressure is applied just at the right place to close expense of the sides. This was the old practice, when lands were laid the junction of the several slices.

very wide and very high ; in common fields, the land or stitch was When the seed is to be dibbled on the sward, which is reversed by often the whole width of the possession, from which came the name of a single ploughing, it is necessary that the sod should be completely land. In Scotland they are called riggs. turned over and laid flat. To do this, and at the same time to bury One of the most useful operations in ploughing land is to cross the all the grass, requires the furrows to be very equal and parallel ; so former furrows, by which means the whole soil is much more comthat when a roller has gone over the land, it is perfectly flat, without pletely stirred, and if any part has been left solid without being any interstices between the slices which are turned over. It requires moved by the plough-share, which is called a balk, it is now necessarily a good ploughman to do this perfectly.

mored. The leaving of balks is a great fault, and is owing to the sole When clover-lea or old grass is ploughed up, it is difficult to bury of the plough being narrower than the furrow-slice, and the wing of the all the grass which grows on the edge of the slice; and if it remains point too short, or to the ploughman not holding his plough upright. exposed, it will grow and increase to the detriment of the corn. To The share should cut the ground to the whole width of the furrow, prevent this, a wing is sometimes added to the side of the coulter, a that no roots of thistles, docks, or other large weeds may escape and few inches from the point, or an alditional skim-coulter is made to grow up again. The Roman authors recommended the use of a sharp precede the ordinary coulter of the plough. It cuts a small horizontal rod or stake inserted horizontally into the ground, to discover if there slice off the surface before the sod is turned over, and this falls into were any balks, which, with their ploughs, must have been often left, the bottom of the furrow and is buried there. The coulter with such if the ploughman was not very careful to make close and small furrows. a wing is called a skim-coulter, because it, as it were, skims the surface. Many ploughmen hold the plough in an oblique position; the bottom This instrument may require an additional horse to be put to the of the furrow is consequently not level, and the soil is not stirred plough in tenacious soils, but this cannot be avoided. There is no equally. This is a great fault, especially in wet ground; for the doubt that no more horses should be put to a plough than can do the furrows thus become channels in which the water remains, not being work; but whatever be the number required, the work must be done able to run over the inequalities of the bottom. It is of no use to lay well. There is no saving in doing the work imperfectly. The dis- the surface convex, if the solid earth below lies in hollows or gutters. cussions about the number of horses which should draw a plough The water naturally sinks down into the newly-ploughed land, and if might easily be settled, if the nature of the soil were sufficiently taken it be undrained it sinks only till it meets the solid bottom which the into consideration. The shape of the plough may make some difference, plough has gone over; if it can run over this into the deeper furrows but the tenacity of the soil makes a much greater.

between the stitches, it evaporates or runs off, and the land is left dry, Very little attention was formerly paid to the straightness of the and so consolidated as to let the water run along the surface without furrows. It was natural to follow the shape of the boundary of the sinking to any depth ; but if the bottom is uneven, it remains in the field, which was seldom straight; and this practice increased gradually hollows, and stagnates there, to the great injury of the growing crops. till no straight furrow was to be seen; and there was a prejudice, if There are various modes of ploughing land when it is intended to not a superstition, in favour of crooked ridges. Those who defended pulverise and expose it to the sun in summer, or the frost in winter, them with the least vehemence, asserted that if crooked furrows were to purify and fertilise it. To expose as great a surface as possible, the not better than the straight, the difference was unimportant; but no whole field is laid in high and narrow ridges, bringing to the surface curves can be laid so perfectly parallel as two straight lines. Every all the fertile portion of the soil, and often also a portion of the subsoil deviation from parallelism causes a defect in the contact of the slices, so as to deepen the productive portion and give more room for the and a loss of force by the obliquity of the draught. A superficial roots to spread in. The simplest method of increasing the surface observer would not perceive this, but minute examination proves it. exposed, when the land is first broken up from pasture, or after Hence equal and straight furrows are a sign of good ploughing. having been some years in grass, and is in a foul state, is called

When the land lies on a dry subsoil, and no more moisture remains in ribbing, or “raftering.” The plough turns up a slice, which it lays it, after continued rains, than is useful to promote vegetation, it may be over flat on the adjoining surface. It does not cover this with the ploughed quite flat. This may be done by a plough with a moveable next slice, as if it were beginning the crown of a stitch, but it takes turn-furrow, or by ploughing in very great widths. The best way is another slice at some distance, and then one parallel to the first, liketo draw a furrow the whole length of the field in the middle, and wise laid flat on the solid part. When the whole field has been so plough towards this from both sides. If the field is wide, it is most ploughed, the surface consists altogether of ridges and furrows; but convenient to plough it into several broad stitches, each a certain only half the surface has been ploughed. No grass appears, if it has number of perches in breadth. A perch (16! feet) is a very common been well done, the unploughed strips being covered by the slices width for a “stitch," and convenient to guide the sower or the drilling raised by the side of them, the two surfaces with grass on them cover machine.

each other. It is left in this state till the grass is rotten, and when On wet undrained soils it is necessary to lay the land in a rounded the sod is broken to pieces by heavy drag-harrows, the land can be form, in order to let the superiluous water run off into furrows, from cross-ploughed and cleaned or fallowed in dry weather. which it is conducted by proper channels into the ditches. In this There is another mode of ridging, when the land has had one or two case half a perch is a common width for each stitch, or land, as it is ploughings, in order to expose it to the frost in winter, and to mellow sometimes called. It requires some practice to lay up a land in a it. The operation is somewhat similar to ribbing, but after the first roun led form from a flat surface. After cross-ploughing and harrowing, slice is turned over, another is added, as deep as the plough can be the first furrow is drawn wide and shallow, and the earth is thrown made to go, so as not to bring up the subsoil; by this means the whole upon the surface to the right: when the plough returns, it takes surface is laid in high ridges and deep furrows; and when this another furrow about nine or ten inches from the first, laying the ploughing is reversed, in spring, the soil which has been exposed to the earth or furrow-slice somewhat obliquely over the first. At the next frost and wind is mixed with the rest, and tends greatly to mellow it. turn another slice is laid, meeting the last at an angle, the first slice This is an excellent preparation for turnips, if the land has been well