£20 Of the Drill-Boxes. Chap. XX, 



Fig. 4. in Plate 2. mews the Length and Thick- 

 nefs of the Steel Spring of a Turnep Seed-box : This 

 ierves both for a Tongue and Spring : It is made 

 firft ftrait, and then the narrowefl End of it is turned 

 round, till it reach to j, and forms the Cylinder A* 

 thro' which its Axis paffes ; but is not welded 6r 

 joined to the other Part of the Spring at a : It is 

 placed in the Box with the Cylinder Part underneath. 

 The Face of this Spring is feen upon its Axis, mark'd 

 K. in Fig. 5. Its Axis is to pafs thro' the Hole E, 

 and fcrew into the Hole F, in Fig. 2, as is feen more 

 plainly ac a in Fig. 9. 



As the Top of every Tongue ought to be even 

 with the upper Edges of the Mortife, the Thicknefs 

 of the Cylinder of the Brafs Tongue caufes the Hole 

 in the Sides of the Mortife, into which it is held by 

 its Axis, to be far enough from the Edges of the 

 Mortife, to be bored and fcrewed without Danger 

 of breaking the faid Edges •, but the Spring of the 

 Turnep-drill being fo very thin, there is fome Dif* 

 faculty in making the Hole fo high, and near the 

 Edges : To prevent which Danger, Fig. J. fhews 

 the End of a fmall hollow Cylinder of Iron or Brafs, 

 of the Thicknefs of the Mortife j which, being put 

 into the Cylinder A, in Fig. 4. raifes the Spring, 

 higher above the Hole ; fo that it may be made as 

 low in a Turnep Mortife, as that is which holds the 

 Brafs Tongue in the Wheat-drill. But we do not 

 always ufe this inner Cylinder (a) ; but mud then 

 take the more Care in boring the Hole, or el'fe it will 

 burfb out at the Edges of the Mortife. 



Its Shape muft conform to that of the Brafs- 

 Tongue already defcribed. 



fa) For, inftead of this, we may nfe a Bit of Woolen Cloth of 

 the Breadth of the Mortife, glued on to the Bottom of the Hop- 

 per, which, filling the Vacuity above the Steel Tongue, prevents 

 any Seed from running over it, though the Holes are bored as low 

 in the Mortife as if the Cylinder Fig. 7. were to be uied. 



The 



