when sowing wheat, or peas and beans, by making the wheels, while they run on the ground, at the exact distance of 54 inches from each other; and, at the time of sowing, by guiding the wheel nearest to the part last sown exactly in the rut last formed; by which means every row will be accurately made, at the distance of 9 inches.
To these observations, Dr. Darwin has subjoined some remarks, tending to evince, by comparison, the essential improvements he has made on this complicated machinery, and from which we extract the following:
1. The simplicity of his drill-plough consists, first, in its having a seed-box only, and not a seed-box and hopper, as is the case with Mr. Cooke's patent drill-plough.
2. The flues, conducting the seed from the bottom of the box into the drill furrows, are not disjoined in the middle, to permit the lower part to move either to the right or left, when the horse deviates from the line in which the coulters pass, as in Mr. Cooke's plough: this defect may be remedied by the simple universal joint at z, (Plate I. Fig. 1).
3. In this machine, the shafts behind, between which the man guiding the coulters walks, are fixed to the coulter-beam, as well as to the axle-tree; whereas, in Mr. Cooke's patent drill-plough, all these are moveable joints, similar to a parallel rule, in order to counteract the swerving of the horse: which, in this machine, is effected by the simple universal joint at z, (Plate I. Fig. 1), already described.
4. The dimensions of the holes in the axis of the seed-box, are here likewise altered, merely by turning a screw, so as to accommodate them to every kind of seeds, which are usually sown on fields, or arable lands.
5. The strong brush of bristles, which sweep over the excavations of the cylinders beneath the seed-box, and strickle them so exactly, that no supernumerary seeds escape; and yet none are either bruised or broken, which sometimes happens in Mr. Tull's original machine.
Lastly, Dr. Darwin justly observes, that the cheaper and more simple the machine is in its construction, the less liable will it be to accidents, which occasion expences in its repair; and, with the greater facility will its management be understood; all which circumstances correspond with its greater simplicity: and, we cordially hope with the Doctor, that the practice of the drill-husbandry will thus be more generally diffused.
Plate II. Fig. 1, is a seed-box, invented by Mr. Swanwick, of Derby, who has liberally offered to shew the working models of the seed-boxes, or to assist any person who may wish to construct either this drill machine, or the preceding one, invented by Dr. Darwin.
Mr. Swanwick's seed-box is 48 inches in length within, and is divided into 6 cells, for the purpose of sowing 6 rows of seeds at the same time, similar to that above specified. At the bottom of each cell is a hole a, a, a, a, a, a, (Fig. 1), through which the seed passes into the seed-flues, as in the machine before described; but this has no revolving axis, there being
