The Plough-head contains the Two Wheels A, B, and their Axis or Spindle of Iron passing thro’ the Box C, turning round both therein, and in the Wheels; the Two Crow-staves D, D, fastened into the Box perpendicularly, and having in each Two Rows of Holes, whereby to raise or sink the Beam, by pinning up or down, the Pillow E, to increase or diminish the Depth of the Furrow; the Gallows F, thro’ which the Crow-staves pass at top, by Mortises, into which they are pinned; G the Wilds with its Links and Crooks of Iron, whereby the whole Plough is drawn; H the Two-chain, which fastens the Plough-tail to the Plough-head, by the Collar I at one End, and by the other End passing thro’ a Hole in the Middle of the Box, is pinned in by the Stake K; L the Bridle-chain, one End whereof is fastened to the Beam by a Pin, and the other End to the Top of the Stake, which Stake is held up to the left Crow-staff, by the With M, patting round it above, and under the End of the Gallows below; or instead of this With, by a Piece of Cord, and sometimes by the End of the Bridle-chain, when that is long enough.
The Plough-tail consists of the Beam N: the Coulter O; the Share P; and the Sheat Q; the Hinder-sheat R, passing thro’ the Beam near its End; S the short Handle, fastened to the Top of the Hinder-sheat by a Pin, and to the Top of the Sheat by another Pin; T the Drock which belongs to the right Side of the Plough-tail, and whereto the Ground-wrist V is fasten’d; as is the Earth-board, whose Fore-part W is seen before the Sheat; and also the long Handle X, whose Fore-part Y appears before the Sheat, and is fasten’d to the Drock by a Pin at a, the other End of which Pin goes into the Beam. Z is the double Retch, which holds up the Sheat, and passes through the Beam to be fasten’d by its Screws and Nuts at b and c.
But without intrenching much farther upon the common Plough-wright’s Art, whose Trade is his Living, I’ll hasten to shew the necessary Difference there is betwixt the common Plough, and the Four-coulter Plough, beginning with [Fig. 2.] where it is represented as standing upon a level Surface.
[Fig. 2.] And, First, The Beam differs in Length, being Ten Feet Four Inches long, as the other Plough-beam is but Eight Feet; it differs in Shape, as the other is strait from one End to the other, but this is strait only from a to b, and thence turns up of a sudden, in the manner that is shewn in the Cut; so that a Line let down perpendicular, from the Corner at a, to the even Surface whereon the Plough stands, would be Eleven Inches and an half, which is its Height in that Place; and, if another Line were let down, from the turning of the Beam at b, to the same Surface, it would be One Foot Eight Inches and an half, which is the Height that the Beam stands from the Ground, at that Part; and a Third Line let down to the Surface, from the Bottom of the Beam, at that Part which bears upon the Pillow, will shew the Beam to be Two Feet Ten Inches high above the Surface in that Part.
From the End a, to the Back-part of the first Coulter, is Three Feet Two Inches; from thence, to the Back of the next Coulter, is Thirteen Inches; thence to the Third, Thirteen Inches; and from thence to the Fourth, the same. From a to b is Seven Feet.
This Crookedness of the Beam is to avoid the too great Length of the foremost Coulters, which would be necessary if the Beam was strait; and then, unless they were vastly thick and heavy, they would be apt to bend, and the Point of the Fourth would be at so great a Distance from its Coulter-hole, that it would have the greater Power to loosen the Wedges, whereby the Coulter would rise up out of its Work, as it never doth when the Beam is made in this bending Manner. This Beam is made either of Ash, which is the lightest, or of Oak, which is the most durable. Its Depth and Breadth may vary, according to the heavier or lighter Soil it is to till; but this before us is in Depth Five Inches at the first Coulter-hole, and in Breadth Four Inches.
[Fig. 4.] Is the Sheat Q in [Fig. 1.] (broad Seven Inches) with the Iron Retch on it, the left Leg of which Retch must stand foremost, to the end that the Edge of its Fore-part, that is flat, may fit close to the Wood of the Sheat: This Retch holds the Sheat fast up to the Beam by its Nuts and Screws; as also doth a Pin driven into the Hole a, which Hole being a small Part of it within the Beam, the Pin being driven into the Hole, draws up the Sheat very tight to the Beam. The principal thing to be taken notice of here, is the Angle b c d, which shews the Elevation of the Sheat; the Line c d is supposed to be equal with the Bottom of the Share (or rather with the plain Surface whereon it stands); when this Angle at c is larger than of Forty-five Degrees, a common Plough never goes well: In my Four-coulter Plough I choose to have it of Forty-two or Forty-three at the most.
