1851 Great Exhibition: Official Catalogue: Class IX.: Sewell and Co

107. SEWELL and CO., Longtown, Cumberland, and 30 Spring Street, Hyde Park - Manufacturers.

Netherby plough, designed to cut, displace, and leave in a proper position, furrows of various widths and depths on moderately stiff soils, where the more "springy" action of a lighter plough increases the traction, and deteriorates the appearance of the work done.

It is sufficiently strong for almost any soil, but for very stiff clays, it requires another form of mould plate; for, like other tools, ploughs should be made for their assigned duty, to prevent disappointment to the farmer.

On observing three or more oxen drawing a single surface plough, it is difficult to resist the conclusion, that only from some constructive or other remediable error, can so much power be required to displace a small quantity of soil only a few inches. This will appear more clearly, by comparing the useful effect of a horse in drawing a waggon and in drawing a plough. The tractive power of a horse is about 150 lbs., which gives 450 lbs. for three horses. The friction of a waggon on a road is from 72 to 90 lbs. per ton, which, taken at the highest estimate, gives five tons that the three horses could draw on a good road.

Now, if about a cubic foot of earth be in motion at once in ploughing, and, with the plough, weighs — say 370 lbs., it gives the comparison — as 370 lbs. is to five tons, or as one is to thirty, so is the practical effect in ploughing to traction on a road. Thirty to one is a discrepancy so wide, that it should induce the matter to be seriously considered by those who till their soil at such a great cost of power, increased by not unfrequently more than one guide.

The principal resistances in ploughing are, the quiescent tenacity of the soil, and its rubbing friction along the mould-plate. The first is the most important; for since the friction of a body at rest is much greater than its moving friction, it follows, that in a well-formed mould- plate, the rubbing friction of the soil can only be limited. To start, displace, and replace the soil with least power, are therefore the requisites of a good plough.

These qualities obtained, a few pounds more or less weight in the implement itself could make no material difference; as the actual weight should depend upon the nature of the soil to be removed. The attachment of the tractive power, however, is of importance; since it should be in, or as near to the direct line of the greatest resistance, as is practicable. The greatest resistance will be between the cutting edge of the coulter and that of the share which fairly starts the soil into motion, as is testified by the greater wear of these parts. Since this point is near the land side, it is evident that horses walking in the previously displaced furrow, are pulling at an angle of several inches from the land, requiring some compensating resistance to keep the plough to the land.

When one horse, however, is attached on each side, and as near to the line of resistance as they can be, their angular traction balances each other, and results in their combined force forming a diagonal line of traction in the direct line of resistance, requiring less power and less guidance to produce straight uniform furrows.

The Netherby plough seeks to lessen resistance by the anti-frictional curvature of the mould plate, allowing the displaced soil to press with less intensity over a larger surface, thereby preventing abrasion; and by the attachment of one horse on each side of the line of resistance, as sufficient power for all ordinary surface work.

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