This Opening of these opposite Semi-ellipses makes it impossible for any thing, of itself, to get into the remaining Parts of this hollow Cylinder, betwixt them and the solid Cylinder, call’d the Spindle, which turns continually therein, when the Wheels are going: For you will see, that if you make a Mark on the Spindle, close to the Side of the Mortise, at the upper End of the longest Ax of the Ellipse; and then turn the Spindle until this Mark come against the lower End of the same Ax; and there make another Mark on the Spindle, close to the Side of the Mortise; and draw a Line from one Mark to the other, parallel to the Ax of the Spindle, which will be the Measure of that Part of the Bevel of the Diameter of the Hole; every Point in this Line will, by an intire Revolution of the Spindle, generate a Circle, which will cut the Ellipse in Two Places, once on the Foreside of its longest Axis, and once on the Back-side or hinder Half of it; and that all these Points, in this Surface of the Spindle, described by these Circles, will enter the Hole, by the said hinder Semi-ellipse, as the Spindle there turns upwards (as it always does); and they will all again come out on the fore Semi-ellipse, as they descend towards the lower End of the said Ax of the Ellipse. As these Points thus come out of the Hole, or (if I may use the Expression) as they emerge, they oppose every thing that would enter the Hole, they still moving from the Hole, and push away from it whatever they meet; nay, if any thing were in the Hole, these Points (whereof this Surface consists) would bring it out by this Semi-ellipse, which is always press’d by the Seed when the Drill is at Work; but as these Points immerge by the other Semi-ellipsis which is behind the Spindle, they can carry with them into the Hole nothing but Air, because the Cover never suffers any thing else to come there from above; and the Seed falls out of the Notches by its own Gravity, just before it reaches the lower End of the transverse Ax, being the Place where the opposite Ellipses are farthest asunder; and none of it is ever carried so far back as the hinder Semi-ellipses; and therefore nothing can be carried into the Hole from below. Thus that Part of the Surface of the Spindle will keep the Hole empty and clear, before ever any Notches are cut; but when the Notches are made on the Spindle, they have yet a much greater Force to drive and expel whatever would enter the Hole, their Shape being such as nothing can enter against their bevel Ends; but what is at their Ends will be thrown presently into the Mortise; insomuch that when a Spindle has been too little for the Hole by a Quarter of an Inch, that is, a sixth Part of the Diameter of the Hole, it will perform very well in drilling large Species of Seeds; and when the Mortise is run empty, nothing at all is found in the Hole, it being thus kept void and clean by the Notches.