Harrows, These benefical implements are of various sizes, and dimensions ; but the harrow most commonly used con sists of ['our buds, with cross mortised sheaths, each bull containing five teeth, of from five to seven inches in length below the bulls, the longest being placed for wards. [farrows of this kind, drawn by one horse, are generally used on most farms for all purposes, though on others large brake harrows consisting of five bulls, each containing six teeth, and worked by two horses, are employed during the fallow process, and for reducing rough land. Some of these brake harrows are con structed with joints, so as to bend, and accommodate their shape to the curvature of ridges. A small har row with short teeth is also used for covering grass seeds, though we have rarely seen any detriment from putting grass seeds as deep into the ground as the teeth of ordinary sized harrows are capable of going.
The object of harrowing being both to drag out quicken weeds, and to cover the seed when sown, it is obvious that implements of different sizes are not only necessary, but even that these implements should be worked in different ways, according to the strength and condition of the soil on which they are employed, and the nature of the work to be executed. When employed to reduce a strong obdurate soil, not more than two should be yoked together, because they are apt to ride and tumble upon each other, and thus impede the work, and execute it imperfectly. It may also be remarked, that on rough soils, harrows ought to be driven as fast as the horses can walk ; because their effect is in direct proportion to the degree of velocity with which they are driven. In ordinary cases, and in every case, where har rowing is meant for covering the seed, three harrows arc the best yoke, because they till up the ground more effectually, and leave fewer vacancies, than when a smaller number is employed. The harrow-man's at tention, at the seed process, should be constantly direct ed to prevent these implements from riding upon each other, and to keep them clear of every impediment, from stones, lumps of earth, or clods, and quickens or grass roots ; for any of these prevents the implement from working with perfection, and causes a mark or trail upon the surface, always unpleasing to the eye, and generally detrimental to the braird or vegetation ol the seed. Harrowing is usually given in different directions, first in length, then across, and finally in length as at first. Careful husbandman study, in the finishing part of the process, to have the harrows drawn in a straight line, without suffering the horses to go in a zig-zag manner, and are also attentive that the horses enter fairly upon the ridge, without making a curve at the outset. In some instances, an excess of harrowing has been found very prejudicial to the succeeding crop; but it is always necessary to give so much as to break the furrow, and level the surface, otherwise the operation is imperfectly performed.
On Rollers.
The roller is an implement frequently used for smoothing the surface of land when in tillage, especially when the processes of summer fallow are going forward. Several kinds of rollers are used in Britain. Some are made of stone, others of wood, according to the nature of the operation intended to be performed. The only material difference in rollers is their weight ; but it should be attended to, when a roller is made of large diameter, that its weight ought to be the greater ; for in proportion to the largeness of its diameter, will be the extent of surface upon which the roller rests. The weight of a roller ought therefore to be in proportion to its diameter, otherwise its effect will be proportionably diminished.
Rolling, however, is a modern improvement, and used for different purposes. In the first place, it is of great advantage to roll young grasses after the ground is stoned, because the lithe can then be placed nearer the surface, and the crop cut more equally than when the operation is neglected. 2dly, Land on which tur nips are to be cultivated can rarely be made fine enough, without the repeated use of this implement. And, idly, The process of summer fallow, upon strong soils, is much advanced by rolling, because, without its aid, the large and obdurate clods cannot be reduced, or couch grass eradicated. From these circumstances it will readily appear, that rollers of carious sizes and dimen sions are required on every farm, for accomplishing dif ferent purposes. \Vooden rollers, drawn by one horse, answer very well for grass and turnip land ; but massy stone rollers, drawn either by two or three horses, are absolutely necessary on clay soils. Alost farms are im perfectly provided with these implements. Every one may have them smaller or larger, but few are provided with a sufficient number. It is obvious, that when a large field is to be rolled, a number of rollers ought at once to be set at work, otherwise an opportunity may be lost, never to be regained. The deficiency is most con spicuous, when barley is taken after turnips in a dry season. From poaching the ground with carts, in or der to carry oil the crop, and even by the treading of sheep, a degree of stiffness is contracted, which requires the use ol the roller before grass seeds can be sown. Suppose that a field so circumstanced should have got two-thirds of the intended harrowing, and that the re mainder is reserved till rolling is given, a delay takes place at all events before grass seeds can he sown ; and where only one roller is employed, that delay may be in creased to such a length as to endanger both barley and seeds, should wetness intervene before the whole opera tions are completed.