The Degree of its Stiffness is known by weighing, as has been directed for the other Spring; and being laid with its Face downwards over a Chink, with a small Piece of Wood of the Thickness of a Barley-corn at Each end, and a String taking hold of its Middle, and descending thro’ the Chink, the Weight of Five Pounds, tied to the End of the String, will just bend the Spring, till it touch the Edges of the Chink; and this is the Stiffness of a Spring that has performed well, for many Years, in drilling of Turnep-seed. _The_ SETTING-SCREW. _Fig._ 6. is the Iron Setting-screw, which passes thro’ the Hole in the Fore-end of the Mortise, _Fig._ 2. and passes up to the Middle of the Spring by the prick’d Line _p q_ in the same Figure. The Use of this Setting-screw is, to increase or diminish the Proportion of Seed to be turned out by the Notches; and this it does by forcing up the Spring and Tongue (where there is one) nearer to, or farther from the Spindle, whereby the Seed-passage is made wider or narrower, as is shewn by the Three prick’d Lines in _Fig._ 2. and _Fig._ 3. Observe, that the prick’d Line _p q_, _Fig._ 2. (being the Mortise of the Turnep-box) stands higher than the same Line doth in _Fig._ 3. which is the Mortise of the Wheat-box. The Reason of this Difference is, because the Spring in the Wheat-box bears at its lower End against the Tongue below the Seed-passage, and at its upper End below the Axis of the Tongue, whereby the Middle of that Spring is lower than the Spring of the Turnep-box, which, being both Spring and Tongue, bears against its Axis above, and against the Seed-passage below; therefore its Middle is higher. This Setting-screw should be placed perpendicular to the Tongue when at its mean or middle Distance from the Spindle, which may be supposed to be the middlemost of the Three mention’d prick’d Lines. This Setting-screw ought to be smooth and round at its End, which bears against the Spring; for, if it should have sharp Corners or Edges, the Spring might be wounded by them, and in time might break there, being press’d by every Notch that turns against it; and, as I have computed it, a Spring undergoes One hundred thousand of these Pressures in one Day’s Work; and yet, in my whole Practice, I have had only one Spring broken, and that was in drilling a large Sort of Peas with a Wheat-drill, and was occasioned by a jagged End of the Setting-screw, which was not placed perpendicular to the Spring, by which means the rough End of the Screw made Scratches against it a Quarter of an Inch long, and so deep, that the Spring broke off there: Let not this Setting-screw be any longer than just to force the Tongue up to the Spindle; for, if it should be longer, an ignorant Driller might happen, by the Force of the Screw, to break the Tongue, or its Axis; but in the Turnep-drill, which has only a Spring instead of a Tongue, the Setting-screw may be a Thread or Two longer; because the