This bottom Board, which holds the brass Seed-box, is Four Inches broad, and full half an Inch thick, and at each End a quarter of an Inch longer than the Seed-box: This Piece is first thrust in sliding upon the Two added Pieces of Board, until its fore End comes under the fore Side of the Hopper, and its hinder End under the hinder Side; then setting the Hopper with its Bottom upwards, the Spindle being thro’ the Seed-box, and Holes of the Hopper, we hold the Seed-box hard upon the Bottom, at equal Distance from each End of it, whilst the Holes are bored thro’ the Bottom, by the Holes at each End of the Seed-box; and then the Screws, being put thro’, screw on the Box; and when that is done, we make a Mark upon the bottom Board, with the Compasses, on each Side of the Brass Box, beginning from the Ends of the Axis of the Tongue, reaching as far backwards as is the Length of the Mortise: These Two Lines or Marks are a Direction for cutting the Hole in the Bottom of the Hopper, thro’ which the Seed descends into the Seed-box; then we pull out the Spindle, then draw out the Bottom, take off the Seed-box, and cut the Hole in the Bottom in the manner I will now describe in [Fig. 14.] where the Two pricked Lines a b and c d are the lower Edges of the Hole, and the same with the Two Lines mentioned to be marked by the Sides of the Seed-box. The pricked Line a d, being at right Angles with the Two former, is the lower Edge of the fore End of the Hole, and exactly over the Axis of the Tongue, and parallel to it. The pricked Line b c is the lower Edge of the hinder End of the Hole, which is just over the hinder End of the Mortise, and parallel and equal to the last-mentioned pricked Line: These Four pricked Lines are the lower Edges of this Hole, contiguous to the Seed-box. The Two Lines e f and g h are the upper Edges of the Sides of the Hole, which, being farther asunder than the lower Edges, make the reverse Bevel of this Hole; which may be determined by this, that the Surface between these Two upper and lower Edges, being Planes, are inclined to one another downwards, in an Angle of about One hundred and Thirty Degrees. The Two Lines e g and f h, at right Angles with the Two last-mentioned Lines, make the upper Edges of the Ends of this Hole; and, being nearer together, than the pricked Lines under them, the plane Surfaces, betwixt these Two Lines and those Two pricked Lines, shew the Bevel of the Ends of these, which are inclined to each other upwards in an Angle of about Sixty-five Degrees.
This double Bevel effectually prevents the Seed from arching in the Hole, before it gets into the Mortise of the Seed-box; and also, the Two upper Edges of the Ends of the Hole being nearer together than the lower, there is the more Wood left between these Edges and the Screws, which hold the Box to the Bottom, whereby the Board is less apt to split.
Then the Box being screwed on to the Bottom, and thrust again into its Place, the Spindle, passing thro’ both the Hopper and the Box, keeps the Bottom in its Place: Then D, in [Fig. 13.] is the imaginary Plane of the Top or Mouth of the Hopper, being a rectangled Parallelogram, and parallel to the Bottom, to which the fore End is perpendicular, and a rectangled Parallelogram of the same Breadth.
[Fig. 15.] shews the fore Side of the whole hinder Hopper, with its Two Cavities, and all its Accoutrements, except the Wheels; the Two Ends A and B being exactly alike, having each of them its Seed-box at the Bottom, in the same manner as in the one has been described. The Bar D holds together the upper Parts of this double Hopper at a right Distance, which is, when there is Ten Inches clear room betwixt the Two single ones. The Spindle E, passing thro’ the Whole, holds the Two single Hoppers by Four Wreaths, at the same Distance below, as they are held by the Bar above.
These Four Wreaths are screwed on to the Spindle, to keep it from moving towards either End, as well as to hold the Hoppers in their Places: Two of which Wreaths are seen at a and b; and the other Two are placed on the Outsides, as these Two are on the Insides. Before we proceed any farther in this Figure, it will be proper to shew the Wreaths, which are of Two Sorts.
The one in [Fig. 16.] where A is its Hollow, which is circular, and must be of the same Diameter with the Spindle; and, being thrust on upon the Spindle, till it touch the Board, is fastened to the Spindle by a small Screw thro’ each of its opposite Holes, a b shews the Breadth of this Wreath, whether it be made of Brass or Wood: It is little more than half an Inch. b c d is the Part of it that goes against the Board: The Thickness of the Surface of this End which goes against the Board, is a quarter of an Inch, if made with Brass; but if with Wood, half an Inch; but the Thickness of its other End a e f is less than its End b c d, by which means the Screws are the more easily turned in.
