Farm-yard manure being spread upon the surface, wheel ploughs drawn by three powerful horses are set to work to plough the land in the usual British way. In wide lands or stitches, after the sod has been turned and laid at an angle of forty-five degrees, the seed is sometimes then sown and harrowed down. But the neatest farmers, instead of sowing at this stage of the work, employ a compressing implement formed of two parallel metal wheels at one end of an axle, and very close to each other, and a guide wheel of the same diameter at the other end. The interior rims of the compressing wheels (or rollers) are four inches wide, and nearly touch each other; the exterior surfaces are narrowed to two inches; these wheels sink into the earth at the junctions of the furrow slices, and by pressing down the grassy edges, and forming perfect grooves at the intervals of seven or nine inches, the seed may be sown with extreme exactness, and without the loss of a single grain, and at a uniform depth. But though the seed is frequently sown with the preparation just stated, the practice of the neatest and most judicious farmers is to harrow down these drills after the rollers have formed and completed them, and then to sow with the Suffolk drill-machine in the free and pulverized surface. This implement forms and sows several shallow drills at each bouting, and with perfect precision; the experienced eye of the man who follows in the rear, enabling him in an instant to perceive any possible irregularity in the movement of the hoppers and distribution of the seed. The great advantage derived from the action of these compressing wheels is, that the grassy edges of the furrow slices are prevented altogether from vegetating by the depth to which they are removed from the surface, and that the pressure of the portions into which the rollers sink, is far more effective and consolidating than if an ordinary broad roller were to pass over the entire area. In preparing any loose fallow land for vetches, these compressing rollers are very serviceable. By following two ploughs, and in the same tracks, the ploughing and the perfect formation of the drills by pressure are accomplished in the same space of time, the two wheels obviously describing double the number of furrows described by each plough in the same period. In heavy clay soils this compression is at least unnecessary, and in stony land drilling is difficult and unadvisable, but in light open soils the advantages of this system are considerable. The proper season for sowing is also a point of great consideration, both as regards the economy of seed of any kind, and the productiveness of the crop.