E

Fig. 7.

Kirkwood's grubber, a figure and description of which were given in a recent number of the Highland Society's Transac tions. But we are induced again to notice it here, both because it falls within the class of instruments which we are now describing, and because various useful improvements have been made upon it since the original figure and description were given in the Society's Transactions.

This instrument, which is formed wholly of iron, consists of a frame-work, as shown in Fig. 7., in which are fixed seven

prongs, or rather blunt coulters, so placed as to move at equal distances from each other, and parallel to the line of motion. The frame-work rests upon three wheels, to the axle of the two posterior of which at BB, are fixed the two guiding handles AA. These handles, which are moveable round the axle at BB, are extended to the cross-bar CC. By depressing the handles they act as levers, of which the fulcrums are BB, and elevate the bar CC, and consequently the posterior part of the frame-work. Further, the part of the machine EF, to which is attached the fore-wheel G, is connected by means of the rods ED, DH, and DL with the handles AA; the same depression of the handles which elevates the hinder part of the instrument, acts upon the upright rods CD, CD, which are moveable round the iron bar CC, at these points. This acting upon the bar at the points CC, moves forward the fore-wheel G, and thus elevates the fore-part of the frame-work, and that in the same degree as the hinder part is elevated. Thus an elevation or depression of the guiding handles elevates or flowers the whole frame-work, and consequently causes the teeth to move at a greater or less depth as may be required. By means of a simple contrivance at the point K, the rod ED is fixed in its position, and thus the whole frame is kept at the elevation required. By depressing the handles sufficiently, the whole teeth may be lifted out of the ground, which is found to be extremely convenient when turning at the end of ridges, and when moving from one field to another, or even when encountering great obstacles in the ground, as stones. The various coulters being also fixed in their place by keys or wedges, may be removed, or set at a greater or less depth as may be required. The space covered by the coulters of this instrument is 4 feet 4 inches. The coulters are 144 inches long below the bars; 2 inches broad, or deep; and ths of an inch thick, or across, except at the point, where they are 14th inch thick. This crossbreadth at the point, when new, both in these coulters and those of Mr Finlayson's harrow, is, as has been stated, 11th inch. But they are soon found, by the greater friction at this part, to wear down to about an inch in cross-breadth, which therefore indicates the proper size of which they ought to be made. The diameter of the hindmost wheels is 22 inches; the weight of the 3 K

VOL. II. NO. XII.

instrument is about 4 cwt., and its price is L. 10. Two horses are in general sufficient for working this machine *.

Of all the instruments of this class which have yet come under our observation, we conceive that of Kirkwood to be the most ingenious, and the most effective with an equal application of power. The method of raising the coulters out of the ground, by means of the handles,—an operation which can be performed in a moment,—is simple and of great utility in practice. The machine possesses, in nearly an equal degree with Mr Finlayson's harrow, the advantage of not being impeded in its motion by the weeds or rubbish which are collected by the teeth or coulters, while it is superior to the latter instrument from the smaller power of draught required.

The introduction of this class of instruments into tillage must be regarded as beneficial and important. They are highly useful in assisting the operations of the summer-fallow. When land is full of root-weeds, the repeated operation of the plough, the harrow, and the roller, are the methods resorted to for tilling and clearing it; but very frequently, when the land is stiff, even the operation of ploughing itself, tends to compress the furrow-slice, and if the influence of the sun be considerable, it will be formed into a hard mass, on which the subsequent operations of the harrow and the roller have little comparative influence. So much is this felt in many of the stiffer clays of England, that

* To these instruments might be added Morton's revolving harrow, to the particular properties of which, however, we may take a future opportunity of recurring. This instrument consists of sets of spikes or prongs, fixed on an axle, round which they revolve like the spokes of a carriage-wheel. This axle is placed oblique to the line of motion, so that the manner in which the teeth work is of a two-fold nature. They partly revolve, and they are partly dragged, like the teeth of the common harrow. The axle consists of two parts converging towards each other, forming the two equal sides of an isosceles triangle. There are ten sets of teeth in all, five being on each side or half of the axle; and each set contains ten spikes or prongs, like the spokes of a wheel, but curved forwards at the point. The machine moves on two wheels, and requires the labour of four horses. The price formerly was L. 18, 18s. Mr Morton, however, the ingenious inventor of it, so well known in Scotland as a maker of agricultural machines, is now employed in simplifying its construction, both for the purpose of lessening the price and diminishing the draught necessary. We hope to give a description and figure of it in its improved form.

it is a very frequent practice to delay giving the first ploughing to the fallow-land till the month of May, by which one of the great benefits of an efficient summer-fallow is lost. But, by means of a well constructed grubber, such land may be cleaned and tilled without the necessity of turning up a new surface. The instrument, too, can be made to go at any depth in the soil which may be required, and thus the land can either be stirred to the depth to which it had been originally ploughed, or to such depth as may be most suitable for the purpose intended, whether that purpose be to clean the land of root-weeds, or to till the soil only a few inches deep.

Further, the grubber may be employed in preparing land in certain cases for the seed, without the necessity of a repetition of the more costly operation of ploughing. Thus land which had been ridged up in autumn or winter, after having produced any of the leguminous crops, as pease or beans, may be prepared for the seed with advantage by using the grubber alone. In this manner, the seed is sown upon the surface mould which had been pulverized by the influence of the sun and frost. In the case, too, of land which had produced a crop of turnips or potatoes, the grubber may, in all cases, obviate the necessity of a second ploughing as a preparation for the seed; and may even, in many cases where the soil is light and dry, obviate the necessity of ploughing at all after the green crop has been removed or consumed.

In tilling with the grubber, it is frequently found expedient to go twice over the ground; and, in this case, it is proper to set the teeth at half the depth required in the first operation, and in the second operation, to set them at the full depth, and in working to cross at right angles to the first operation. This, with a few turns afterwards of the common harrow, will constitute a very efficient tillage. The use of the grubber in agriculture, it is to be observed, does not supersede that of the harrow, the latter being still employed for the further pulverization of the soil, and for collecting into heaps the weeds and rubbish brought to the surface by the grubber. Although the grubber is in pretty general use in a few well cultivated districts, it is very far from being so generally adopted as it ought to be. Although it may be employed

with the greatest effect on the lighter class of soils, it may be employed on any land, however stiff, provided it is preceded by one and sometimes two ploughings. In comparing the grubber with the plough in point of economy of labour-taking Mr Kirkwood's instrument for example-the breadth of ground covered by it at one operation is, as has been stated, 4 feet 4 inches; and the ordinary breadth turned over by the plough, at one operation, is nine inches. Now, one pair of horses with the plough can, upon an average, turn over one acre of land in a day, and one pair of horses with the grubber, in the same time, and at the same rate, would go over nearly six acres. But, in truth, one pair of horses with the grubber can move at a considerably quicker rate than with the plough; and this illustration is sufficient to show the direct economy of labour which may be effected by the use of the grubber. Besides, however, the mere economy of labour by the employment of this implement, the land can frequently be cleaned and sown much earlier than if the plough and harrow only were employed, and this is an advantage which, as every farmer knows, may prove of great importance to the productiveness of the future crop.

ON THE CAUSES AND PREVENTION OF FOOT-ROT IN SHEEP. By Mr DICK, Veterinary Surgeon, Edinburgh.

THE foot-rot in sheep is a subject of so much importance to the agriculturist, and the disease has prevailed to such an extent during the last two years, that any apology for offering a few remarks upon it would be superfluous. Indeed, its destructive effects are at any time such as to call attention to this subject; and the differences of opinion which exist regarding the causes which produce the disease, the means of preventing it, and the remedies for it, plainly show that the subject is as yet but imperfectly understood.

There are some points of importance to be kept in view, in order to understand properly either the functions of the foot of the sheep, or the nature of the diseases to which it is liable. The foot presents a structure and arrangement of parts well adapted to the natural habits of the animal. It is divided into