The Drill is the Engine that plants our Corn and other Seeds in Rows: It makes the Chanels, sows the Seed into them, and covers them at the same time, with great Exactness and Expedition. The principal Parts of the Drill are, the Seed-box, the Hopper, and the Plough, with its Harrow. Of these the Seed-box is the Chief: It measures (or rather numbers) out the Seed which it receives from the Hopper: It is for this Purpose as an artificial Hand, which performs the Task of delivering out the Seed, more equally than can be done by a natural Hand. It is described, together with some of its Appurtenances, in _Plates_ 2 and 3. _The_ MORTISE. As the Seed-box is the principal Part of a Drill, so is the Mortise the principal Part of the Seed-box. The following Descriptions shew how this Mortise differs from a common Mortise. Fig. 1. _Plate_ 2. shews both the upper and lower Edges of a Turnep-Seed-box, and the Manner how they are posited one over another, _a b c d_ is a rectangled Parallelogram, and shews the upper Edges (or Top) of the Mortise. _e f g h_, being a Figure of the same Denomination with the former, is the lower Edges (or Bottom) of the Mortise. The Line _e h_ is the Length of the lower Edge of the Hinder-end of the Mortise. _a d_ is the upper Edge of the Hinder-end of the Mortise, and posited just over the lower Edge of the same End. The Space between the Line _a b_, and the Line _e f_, shews half the Excess whereby the Bottom of the Mortise exceeds the Top in Breadth; as the Space on the opposite Side, betwixt the Line _c d_, and the Line _g h_, shews the other Half of that Excess, both which Halves, taken together, shew the whole Bevel (or Angle of Inclination) described in _Fig._ 2. That Part of the Line _a b_, from the Angle at _b_ to the Line _f g_, which intersects it, shews the Excess whereby the Top of the Mortise exceeds the Bottom in Length. _Fig._ 2. Is the Mortise cut down by its Four Corners, and laid open. _a b c d_ is a Trapezium, with Two parallel Sides, and mark’d A, the right Side of the Mortise; its opposite Side _e f g h_, mark’d B, the left Side of the Mortise; the Areas of both being true Planes[261]. [261] Take care that these opposite Sides be sure to be true Planes, especially all that Part of their Areas, that is before the transverse Axes of their Ellipses herein after described; for should they be otherwise, the Bevel of the Mortise would be spoiled, and so would the Ellipses, and the acute Triangles, on the Sides of the Tongue; which how necessary they are to be true, is shewn in the proper Place. Workmen are very apt to fail in this when they file by Hand, and make these Sides of the Mortise convex instead of plane. Therefore this might be done with less Difficulty, and more Exactness, with a File placed in a Frame, whereby it might move upon a true Level without rising or sinking of either End.