had broken out between him and Mamun, in which Theo- | Ibn Khaldun, besides various other works of high interest, philus was unsuccessful. He was, like his antagonist, a wrote a history of the Berbers; Haji Khalfa composed a friend to science, and, in order to negotiate a peace, sent the bibliographic work on the history of literature among the celebrated scholar Joannes Grammaticus as ambassador to Arabs, Persians, and Turks. the court of the caliph. The assistance and advice of this envoy were of great value in the scientific undertakings then encouraged by Mamun; and Joannes was so much in favour at Bagdad, that he would doubtless have effected a reconciliation between the two courts, had not the caliph died in the midst of the negotiation. In the subsequent times of the caliphat, the Emirs al Omara and the Bawaihide (Buide) sultans encouraged literature; in almost all the dynasties which sprung out of the caliphat, there were some sovereigns, at least, who loved the sciences and patronized scholars. The dynasty of the Fatemides in Egypt is in this respect distinguished. Ibrahim ben Aglab, the founder of the Aglabide dynasty, made Kairwan a seat of learning; and Zeiri encouraged literature in the town of Afshir, which he had founded in the territory of the present Algiers. In Spain, the Ommaiade caliphs followed the example of Al-Mansur and his successors. An exchange of learned ambassadors took place between Abdorrahman III. (912-961) and the German Emperor Otto I. His son Hakem founded the university of Cordova, and many colleges and libraries in Spain; his own library is said to have contained not less than 600,000 volumes. Gerbert of Aurillac, who afterwards ascended the papal throne as Sylvester II., studied at Cordova, and introduced into Europe the Arabic decimal system of numerical notation, for which the Arabs themselves were indebted to the Hindoos. Several English scholars, Adelard or Adhelard of Bath, in the eleventh, and Robert and Daniel Morley in the twelfth century, also visited the Arabic universities of Spain. It was through Spain, and through the Arabic versions, that the attention of the schoolmen was first drawn to the writings of Aristotle. Among the Arabic philosophers, Pococke (in a note prefixed to his edition of Ebn Tofail) selects the following as the most distinguished: Abu Nasr Mohammed al-Farabi (died A.D. 942), Abu Ali al-Hossein ben Abdallah ben Sina, commonly called Avicenna (born A.D. 980), Abu Hamed Mohammed al-Gazali (d. A.D. 1111), Abu Bekr Mohammed ben Yahya ben Baja, commonly called Avenpace (d. A.D. 129 or 1139), Abu'l-Walid Mohammed ben Ahmed ben Mohammed ben Roshd, commonly called Averroes (d. A.D. 1198), and Abu'l-Kasem al-Jonaid (d. A.D. 910). Some of the most celebrated Arabic writers on mathematics and astronomy are the Sabian Thabet ben Korra, the Christian Is'hak ben Honain, Mohammed ben Musa, Jaber ben Afla, Behaeddin of Amol, Mohammed ben Jaber al-Battani, Al-Fergani, Ibn Yunis, Abu'l-Hassan Kushyar, Ulugh-Beg, &c. Damiri, Ibn Beitar, and Kazwini, left books on natural history; the latter is also the author of a work on geography. Peculiar to the Arabic geographers is the division of the earth (the northern hemisphere) into seven climates, or as many zones, which are counted from the equator towards the north pole, and are measured by the increase of the duration of daylight at the summer-solstice. Among the Arabic writers on geography we must notice Ibn Khordadbeh, Istakhri, Abu Is hak al-Faresi and Ibn Haukal, who flourished in the tenth century; the Sherif Edrisi (often called Geographus Nubiensis), who lived in the twelfth century in Sicily under Roger I.; Omar Ibn-al-Wardi; Yakuti (d. 1249), and AlOsyuti. More information than from the professedly geogra phical works of some of these writers, may perhaps still be obtained from the accounts given by Arabic travellers of the countries which they had visited. Al-Hassan ben Mohammed al-Wassan al-Fasi, of Grenada, commonly known under the name of Leo Africanus, travelled through Asia and Africa: Ibn Waheb and Abu Zeid al-Hassan visited India and China in the ninth century; Selam al-Tarjoman visited central Asia during the reign of the caliph Wathek; Abdal-Rizzak travelled in the fifteenth century as ambassador from Persia to India; Mohammed Ibn Batuta wandered in the fourteenth century through the interior of Africa, India, Java, China, Russia, Greece, Spain, &c. A history of Arabic literature is still wanted. A good account of the works printed in Arabic till the year 1811 may be found in Schnurrer's Bibliotheca Arabica. Those who want further information on the subject of Arabic literature must consult the Notices et Extraits des MSS. de la Bibliothèque du Roi, the Bibliotheca Arabica Escurialensis of Casiri, the Bibliotheca Orientalis of Assemani, the Chrestomathie Arabe and other works published by De Sacy, Moeller's Catalogue of the Arabic MSS. at Gotha, Uri's and Nicoll's catalogues of the MSS. in the Bodleian library, the Mines de l'Orient, the Bibliothèque Orientale of D'Herbelot, &c. ARABIAN GULF. [See RED SEA.] ARABIAN NIGHTS. [See ARABIA, p. 219.] ARA'BII were, according to St. Augustin (Hæres. c. 83), a sect of Christians in Arabia, who believed the human soul to be mortal, and that it is dissolved by death together with the body, but will be restored to life at the resurrection. Mosheim (in Commentariis de Rebus Christianorum ante Constantinum Magnum, ed. 1753, p. 718, seq.) thinks, that the materialism of Epicurus had some influence on the origin of this sect: but it is more likely that the prevailing opinion in those days of the materiality of the human soul occasioned their heretical inferences. The Arabii were confuted and converted by Origen in a synod held in Arabia, A.D. 246 (Mansi, Collectio Conciliorum, t. i. p. 789). ARABLE LAND, so called from the Latin word ardr to plough, is that part of the land which is chiefly cultivated by means of the plough. Land in general is divided into arable, grass land, wood land, common pasture, and waste. The first of these is by far the most important in agriculture. In this article we shall briefly explain the principles on which are founded the most improved methods of cultivating arable land, by which the natural produce of the soil is greatly increased, and many productions are obtained in perfection which are foreign to the soil and climate. We shall, first, consider the nature and properties of va rious soils. The literature of the Arabs is particularly important on account of its numerous and valuable historical works: of most of the following authors in this department, the reader will find some account by turning to their respective articles. The earliest historical writer of the Arabs, of whom we have any knowledge, was Hesham ben Mohammed ben Shoaib al-Khelebi (d. A.D. 826). In the same century lived Ibn Koteiba, Abu Obeida, Mohammed ben Omar al-Wakedi, Abu'l-Abbas Ahmed al-Beladsori, and Asraki. Since the beginning of the tenth century, history became a favourite study of the learned Arabians. Masudi, Tabari, Hamza of Isfahan, and the Christian patriarch of Alexandria Eutychius, also called Said ben Batrik, were among the carliest authors of works on universal history. They were followed by Abulfaraj, George Elmakin, Ibn al-Amid, Ibn al-Athir, Mohammed Hemavi, Abulfeda, Nuweiri, Jelaleddin Soyuti, Ibn Shohna, Abu'l-Abbas Ahmed al-Dimeshki, &c. 2. The best modes of preparing and improving the naAbu'l-Kasem Khalef ben Abdalmalek ben Baskwal of Cor-tural soil, so as to increase its produce. dova (d. 1139), Temimi, Ibn Khatib, Ibn Alabar, Ahmed ben Yahya al-Dhobi, and Shehabeddin Ahmed al-Mokri (or al-Makari) wrote chronicles of the Arabian dominion in Spain; Kotbeddin in the sixteenth, and Abu'l-Hassan Bekri in the eighteenth century, composed histories of Mecca; Omar ben Ahmed Kemaleddin (d. 1261) wrote a chronicle of Aleppo; Ibn Khallican, Ibn Abi Oseibia, Dsahebi, and others, compiled biographical dictionaries; Makrizi, Abdallatif, Shehabeddin ben Abi Hijla, Marai ben Yussuf alHanbali, Jemaleddin Yussuf ben Tagri Bardi, and Mohammed ben al-Moti, wrote special works on the history of Egypt; Behaeddin and Emadeddin wrote biographies of the Sultan Saladin; Ibn Arabshah described the life of Timur; 3. The most advantageous succession of crops, so as to obtain the greatest returns, with the least diminution of fertility. Of Soils.-When the surface of the earth is penetrated, we generally find that the appearance, texture, and colour vary at different depths. There is a layer of earth Rearest the surface, of greater or less thickness, which covers the more solid and uniform materials which lie below it. This may be particularly observed wherever there are natural or artificial excavations or pits. A distinct line, nearly parallel to the surface, generally marks the depth of the upper soil, and separates it from the sub-soil. The soil is more or less composed of minute parts of various kinds of earth, mixed with animal and vegetable substances, in different states of decomposition; and to these, in a great measure, it owes its colour, which is generally darker than that of the sub-soil. Except where iron, peat, coal, or slate abound in the soil, a dark colour is an indication of corresponding fertility. The rich soil of gardens, long cultivated and highly manured, is nearly black. As the soil is the bed in which all vegetable productions are to be reared, and in which they are to find their proper nourishment, its texture and composition become objects of great importance to the cultivator; and, without a competent knowledge of these, no practical rules can be laid down or depended upon. All soils are composed of earths,* metallic oxides, saline substances, vegetable and animal matter, and water. The earths are chiefly clay or alumina, flint or silica, and lime. Magnesia, barytes, and other earths are occasionally met with, but in so few instances that they may be omitted in the list. Of the metals, the most abundant is iron in the state of peroxide. The other metals are rarely found near the surface. Saline substances form a small part of a soil, but an important one. Potassa exists in almost every vegetable, soda in a few, and ammonia is produced by the decomposition of animal matter, but from its volatile nature it is not long retained in the soil, except when it forms a fixed compound with other substances. The vegetable acids, as a general rule, are perhaps limited to small portions of acetic acid in combination with some base, as lime or potash. The mineral acids are found united with earths and alkalies, in the state of neutral compounds. These saline substances have a powerful effect on vegetation, and a knowledge of their proportions in the soil and of their various qualities, is indispensable in order to modify or correct their action by other substances for which they have an affinity. Water, in a state of combination, or of mere mechanical diffusion, is essential to the growth of all plants: without it, and atmospheric air, there is no life either animal or vegetable. Of the Earths.-Clay or alumina, so called because it is obtained in its purest state from alum, in which it is combined with the sulphuric acid, is the basis of all strong and heavy soils. When it is minutely divided, it is easily suspended in water; when dried slowly, and stirred while drying, it becomes a fine powder soft to the feel, and when kneaded with water, a tough ductile mass easily moulded into hollow vessels, which retain liquids. This property, of being impervious to water, gives the specific character to clay as an ingredient of the soil. In a pure and unmixed state it is absolutely barren. When clay is heated to a great degree, it parts with the water combined with it; it is then said to be baked, as we see in bricks. It is no longer diffusible in water, and differs little from silica or зand in its effects on the soil. Silica, or the earth of flints. suffers no change in water. It consists of crystals, or fragments, of very hard stone, forming gravel or sand according to their size; and the finest siliceous sand, when examined with a magnifying glass, has the appearance of irregular fragments of stone without any cohesion between them. Siliceous sand holds water in its interstices by simple cohesive attraction in proportion to its fineness. It heats and cools rapidly, letting the water pass through it readily, either by filtration or evaporation. Its use in the soil is to keep it open, to let the air and water, as well as those other substances on which the growth of plants depends, circulate through it. Unmixed, it dries so rapidly that no vegetation can continue in it, unless a constant supply of moisture be given by irrigation. A small portion of clay will much improve light sands; it takes a large quantity of sand to correct the tenacity of clay. Lime in its pure state is familiar to every one as the basis of the mortar used in building. It is produced by burning marble, chalk, limestone, or shells, in a great heat. In the stones which are formed principally of lime it is combined We retain the old division, although the earths have been ascertained to be oxides of peculiar metals, but as they are never found in the soil in their metallic state, the results and reasonings are not affected by this circum+ Sulphuric acid, commonly calied oil of vitriol, is composed of sulphur and ezygen, which is the pure or vital part of the atmosphere. [See AIR.] stance. with some acid, most generally the carbonic acid, which separates from it by the operation of burning, in the form of an air or gas, hence called fixed air, from its being thus fixed in a stone. These stones, of various degrees of hardness, are now all classed under the name of carbonates of lime. Lime unites readily with water, which it also absorbs from the atmosphere. It then becomes slaked. By uniting with carbonic acid, it returns to its former state of carbonate; with this difference, that, unless much water be present, it remains a fine impalpable powder. Pure lime is soluble in water, though sparingly; a pint of water cannot dissolve more than about twenty grains: the carbonate is not soluble in water. Carbonate of lime has a powerful effect on the fertility of a soil, and no soil is very productive without it. It is consequently used extensively as an improver of the soil, otherwise called a manure; but its use in this respect, and the mode in which it acts, will be given in the articles MANURE and LIME. Carbonate of lime, as an earth, is neither so tenacious as clay, nor so loose as sand. In proportion to the fineness of its particles it approaches to the one or the other, and when the parts are large and hard it takes the name of limestone gravel. Its distinguishing feature is its solubility in acids, which it neutralizes, depriving them of their noxious qualities in the soil. A proper mixture of these three earths, in a due state of mechanical division, forms a soil well fitted to the growth of every species of plants, especially those which are cultivated for food; and nothing more is required than a proper climate as to heat, a proper degree of moisture, and sufficient nourishment, to make all the plants generally cultivated thrive most luxuriantly in such a mixture, which is usually called a loam. But there are some soils, which, besides a proper mechanical texture and mixture of earths, contain a large proportion of a natural manure which renders them extremely fertile. This is a substance produced by the slow decay of animal and vegetable matter. It can be separated from the other parts of the soil, and has been accurately analyzed and described by many of the most experienced chemists, particularly by Fourcroy, Davy, Chaptal, and Theodore de Saussure. (See Recherches Chimiques sur la Vegetation, Paris, 1804, 8vo.) This substance has been called vegetable mould; but, as this is not a very distinct term, we shall, after Thaer and other eminent writers on agriculture, adopt the name of humus when speaking of it. Humus is a dark, unctuous, friable substance, nearly uniform in its appearance. It is a compound of oxygen, hydrogen, carbon, and nitrogen, which, with the exception of nitrogen, which is found only in some substances, are the elements of all animal and vegetable substances. It is the result of the slow decomposition of organic matter in the earth, and is found in the greatest abundance in rich garden mould, or old neglected dunghills. It varies somewhat in its qualities and composition, according to the substances from which it has been formed, and the circumstances attending their decay. It is the product of organic power, such as cannot be compounded chemically. Besides the four essential elements in its composition, it also contains other substances in smaller quantities, viz., phosphoric and sulphuric acids combined with some base, and also earths and salts. Humus is the product of living matter and the source of it. It affords food to organization. Without it nothing material can have life. The greater the number of living creatures, the more humus is formed; and the more humus, the greater the supply of nourishment and life. Every organic being in life adds to itself the raw materials of nature, and forms humus, which increases as men, animals, and plants increase in any portion of the earth. It is diminished by the process of vegetation, and wasted by being carried into the ocean by the waters, or it is carried into the atmosphere by the agency of the oxygen of the air, which converts it into gaseous matter. (See Thaer, Grundsätze der Rationellen Landwirthshaft, Berlin, 1810, four vols. 4to.) Humus, in the state in which it is usually found in the earth, is not soluble in water, and we might have some difficulty in comprehending how it enters into the minute vessels of the roots of plants; but here the admirable provision of nature may be observed. Humus is insoluble and antiseptic; it resists further decomposition in itself, and in other substances in contact with it. It remains for a long time in the earth unimpaired; but no sooner is it brought into contact with the atmosphere, by the process of cultivation, than an action begins. Part of its carbon uniting with the oxygen of the atmosphere, produces carbonic acid, which the green parts of plants readily absorb while its hydrogen with the same forms water, without which plants cannot live; and in very warm climates, where this process goes on more rapidly, the moisture thus produced keeps up vegetable life, when rains and dews fail. The residue becomes a soluble extract, and in that state is taken up readily by the fibres of the roots. But the changes still go on; the extract absorbs more oxygen, and becomes once more insoluble, in the form of a film, which Foureroy calls vegetable albumen, and which contains a small portion of nitrogen, readily accounted for. By bringing fresh portions of humus to the surface and permitting the access of air to it, more carbonic acid, water, extract, and albumen are formed, and give a regular supply to the plants, which, by their living powers, produce the various substances found in the vegetable kingdom of nature. Hence we see the great importance of frequently stirring the surface of the earth between cabbages and other vegetables. It is to the patience and perseverance of the chemists above-named that we owe this insight into the wonderful process of vegetable growth. What we here state is on their authority. We can now readily understand the great importance of humus, and of those rich manures which are readily converted into it, when not immediately absorbed by plants. But it has still another property, highly important to fertility it renders stiff clays porous, and consolidates loose sands. It does so more than lime, or any other earth. Hence a soil with a considerable proportion of humus is much more fertile than the quantity of alumina, or of sand, in its composition would lead one to expect, as we shall see when we come to the analysis of soils of known fertility; and we see the great advantage of animal and vegetable manures, not only as nourishment to vegetables, but as mechanical improvers of the texture of soils. The greatest enemy of humus is stagnant water; it renders it acid and astringent, as we see in peat; and soils abounding with vegetable matters, from which water is not properly drained, become sour, as is very justly said, and produce only rushes and other useless and unpalatable plants. The remedy is simple and obvious; drain well, and neutralize the acid with lime; by these means abundant fertility will be restored. In very light soils humus is seldom found in any quantity, being too much exposed to the air, and rapidly decomposed; the extract is washed through them by the waters, and as they waste manure rapidly, they are called hungry. Such soils are very unprofitable, until they are improved and consolidated by clay or marl, which makes them retain the moisture. With calcareous earths humus acts well, provided they are pulverized and of sufficient depth. Some chalky soils are rendered very fertile by judicious culture and manuring. In order to ascertain the probable fertility of a soil, it is very useful to analyze it and find out the proportion of its component parts. To do this with great accuracy requires the knowledge of an experienced chemist; but, to a certain degree, it may be easily done by any person possessed of an accurate balance and weights, and a little spirits of salts, or muriatic acid. For this purpose, some of the soil, taken at different depths, not too near the surface (from four to eight inches, if the soil is uniform in appearance), is dried in the sun till it pulverizes in the hand, and feels quite dry the small stones and roots are taken out, but not minute fibres. A convenient portion of this is accurately weighed: it is then heated in a porcelain-cup, over a lamp, or clear fire, and stirred, till a chip or straw put in it turns brown. It is then set to cool, and weighed; the loss of weight is the water, which it is of importance to notice. Some soils, to appearance quite dry, contain a large proportion of water, others scarcely any. It is then pulverized and sifted, which separates the fibres and coarser parts. The remainder, again weighed, is stirred in four or five times its weight of pure water; after standing a few minutes to settle, the water is poured off, and it contains most of the humus and soluble substances. The humus is obtained by filtration, well-dried over the lamp, and weighed. The soluble substances are obtained by evaporating the water; but, unless there is a decidedly saline taste, this may be neglected. The humus may be further examined by heating it red hot in a cru cible, and stirring it with a piece of the stem of a tobaccopipe, when the vegetable part will be consumed, and the earths remain behind; thus the exact quantity of pure vegetable humus is found. Some muriatic acid, diluted with five times its weight of water, is added to the deposit left after pouring off the water containing the humus and soluble matter; the whole is agitated, and more acid added gradually, as long as effervescence takes place, and until the mixture remains decidedly acid, which indicates that all the calcareous earth is dissolved. Should there be a great proportion of this, the whole may be boiled, adding muriatic acid gradually, till all effervescence ceases; what remains, after washing it well, is siliceous and argillaceous earth. These are separated by agitation, allowing the siliceous part to settle, which it does in a few seconds. The alumina is poured off with the water, filtrated, heated over the lamp, and weighed,-the same with the siliceous sand. The less of weight is calcareous earth. In this manner, but with greater care and more accurate tests, various soils of knowi fertility have been analyzed, of which we will give a few examples. A very rich soil near Drayton, Middlesex, examined by Davy, consisted of of siliceous sand and of impalpable powder, which, analyzed, was found to be composed of Below this are very poor rye-lands. Very insignificant quantities. 75 70 65 2 60 60 2 14 30 In all these soils the depth is supposed the same, and the quality uniform to the depth of at least six inches; the subsoil sound, and neither too wet nor too dry. Nos. 1, 2, and 3, are alluvial soils, and from the division and the intimate union of the humus, are not so heavy and stiff as the quantity of clay would indicate. No. 4 is a rich clay loam, such as is found in many parts of England, neither too heavy nor too loose,-a soil easily kept in heart by judicious cultivation. No. 5 is very light and rich, and best adapted for gardens and orchards, but not for corn; hence its comparative value can scarcely be given. Nos. 6, 7, 8, are good soils; the quantity of carbonate of lime in No. 8 compensates for the smaller portion of humus. This land requires manure, as well as the others below. In those from No. 9, downwards, lime or marl would be the greatest improvement. Nos. 15 and 16 are poor light soils, requiring clay and much manure. But even these lands will repay the cost of judicious cultivation, and rise in value. The last column, of comparative value, is the result of several years' careful valuation of the returns, after labour and seed had been deducted. Few soils in England contain more than 4 or 5 per cent. of humus, even when in very good heart; and 2 per cent., with a good loamy texture, will render a soil fit for corn with judicious cultivation. The texture is of most importance, as may be seen by comparing Nos. 7 and 8 with No. 6. If this is of good quality, dung will soon give the proper supply of humus. The depth of the soil and the nature of the subsoil greatly affect its value. However rich it may be, if there is only a thin layer of good soil over a sharp gravel or a wet clay, it can never be very productive: in the first case, it will be parched in dry weather; and in the latter, converted into mud by every continued rain. If the subsoil be loam or chalk, six inches of good soil will be sufficient. With a foot of good soil, the subsoil is of little consequence, provided it be dry, and the water can find a ready outlet. The best alluvial soils are generally deep, the chalky shallow. The exposure, with respect to the sun, and the declivity of the ground, are very important circumstances, and equivalent to an actual difference in the climate. A gentle declivity towards the south, and a shelter against cold winds, may make as great a difference as several degrees of latitude; and in comparing the value of similar lands in different climates, the average heat and moisture in each must be accurately known. A soil very fertile in the south of Europe may be very unproductive in England; and a light soil of some value in the west of Scotland might be absolutely barren in Italy or Spain. Of the Cultivation of the Soil.-The better the soil, the less cultivation it requires to produce tolerable crops; hence, where the land is very rich, we find in general a slovenly culture; where the ground is less productive, more labour and skill are applied to compensate for the want of natural fertility. The simplest cultivation is that of the spade, the hoe, and the rake,-and on a small scale it is the best; but spade husbandry cannot be carried to a great extent without employing more hands than can be spared from other occupations. The plough, drawn by oxen or horses, is the chief instrument of tillage, and has been so in all ages and nations of which we have any records. Its general form is familiar to every one, and requires no minute description. The various kinds of ploughs in use at different times, and the improvements which have been made, and are attempted daily, will be noticed in a separate article [see PLOUGH]. Suffice it to say, at present, that a plough should as much as possible imitate the work done with a spade. It should cut a slice from the land by its coulter (a) vertically, and by the share (b), horizontally lift it up, and turn it quite over by means of the mould-board (c); and the art of the ploughman consists in doing this perfectly, and with such a depth and width as suit the soil and the intended purpose. In rich mellow soils a ploughed field should differ little from a garden dug with the spade. In tenacious soils, the slice will be continued without breaking, especially if bound by the fibres and roots of plants; the whole surface will be turned over, and the roots exposed to the air: it is of great consequence that each slice be of the same width and thick ness, and the sides of it perfectly straight and parallel. The plane of the coulter must be perfectly vertical, and that of the share horizontal, in order that the bottom of the furrow may be level, without hollows or baulks, which are irregularities produced by the rising or sinking of the plough, or inclining it to either side. The antients were very particular in this respect, and recommended sounding the earth with a sharp stake, to ascertain whether the ploughman had [Plenty's Improved Flemish Plough, with one wheel and skim conlter.] This plough differs from the common swing plough, in having a small wheel (k) by which the depth of the furrow is more easily regulated.-and a skim coulter (i), which pares off the grass and weeds and turns them into the bottom of the furrow; it is also broader at the point. It is suited to light friable soils. done his duty. There are various modes of ploughing land, | either quite flat, or in lands or stitches, as they are called in England, and, in Scotland, riggs, that is, in portions of greater or less width, with a double furrow between themsomewhat like beds in a garden. Sometimes two ridges are set up against each other, which is called ridging or bouting; the land then is entirely laid in high ridges and deep furrows, by which it is more exposed to the influence of the atmosphere and kept drier; this is generally done before winter, especially in stiff wet soils. Sometimes two or more ridges are made on each side, forming narrow stitches. When the ground is to be ploughed without being laid in lands or stitches, and all the ridges inclined one way, the mouldboard of the plough is shifted at each turn from one side to the other. The plough which admits of this is called a turn wrest plough, and is in general use in Kent, and in many parts of the continent, where the subsoil is dry and the land not too moist. In most other situations the ground is laid in lands, and the mould-board of the plough is fixed on the right side. When grass land or stubble is ploughed, care must be taken to bury the grass and weeds completely, and the slice cut off by the plough must be turned over entirely, which is best done by making the width of the furrow greater than the depth. When the grass and weeds are rotten, and the ground is ploughed to pulverize it, a narrow deep furrow is best; the earth ploughed up is laid against the side of the preceding ridge which forms a small furrow between the tops of the ridges. well adapted for the seed to lodge in and to be readily covered with the harrows. Nothing has divided both practical and theoretical agriculturists more than the question whether the land should be ploughed deep or shallow; but a very slight attention to the purposes for which land is ploughed, and to the nature of the soil, will readily reconcile these apparently contradictory opinions. A deep, rich, and stiff soil can never be moved too much nor too deep: deep ploughing brings up rich earth, admits the air and water readily, and gives room for the roots to shoot, whilst the rich compact soil affords moisture and nourishment. Wherever trees are to be planted, the ground should be stirred as deep as possible, even in a poor soil for grass and corn, this is not always prudent; their roots seldom go above three or four inches deep, and if they find sufficient moisture and humus, they require little more depth. Whenever the soil below a certain depth is of an inferior quality, there can be no use in bringing it up; and where the soil is light and porous, the bottom had much better not be broken. Norfolk farmers know this well, and are very careful not to break the pan, as they call it, in their light lands: this pan is formed by the pressure of the sole of the plough and the tread of the horses, and opposes a useful bank to the too rapid filtration of the water; it lies from five to eight inches below the surface. If it is broken, the manure is washed down into the light subsoil, and the crop suffers, especially when sheep have been folded, their dung being very soluble. In such soils an artificial pan may be formed by the land-presser or pressdrill. This instrument consists of two very heavy cast-iron wheels, a a, with angular edges, set on an axle, at a distance from each other equal to the width of the furrows, and a lighter wheel, b, to keep the instrument vertical. It is drawn by a horse immediately after the plough, pressing two furrows at once, and going twice over each furrow. It leaves the land in regular drills, and the seed sown by hand falls into the bottom of the drills, and is covered by the harrows. When the plants come up they appear in regular parallel rows. The great object in ploughing land is to divide it, expuse every part of it to the influence of the elements, and destroy every plant or weed but those which are sown in it. To do this perfectly requires several ploughings, with certain intervals, and during that time no crop can be upon the land This is the real use of fallows, and not, as was ente supposed, to allow the land to rest; on the contrary, t ought then to have the least repose. |