3 24 Of the Drill-Boxes. Chap. XX. 



to its Place, at every Interval betwixt Notch and 

 Notch. 



The bell Way, that I can think of, to fhew the 

 making of thefe Notches, is by a Section of the 

 Spindle at right Angles, in the Middle of the Notches, 

 as in Fig. 4. of Plate 3. which is a Circle whofe 

 Circumference is cut off by Six Notches j which 

 fhew the different Sort of Notches, that increafe or 

 diminifh the Proportion of Seed to be carried thro 3 

 the Seed-pafTage by them: The Length of the 

 Notches we never alter; but make them always pa- 

 rallel to the Axis of the Spindle, and of the Length 

 of the Diftance there is between the lower Ends of 

 the oppofite Axes tranfverfi of the Ellipfes, or great 

 Holes, of the Mortife \ for if any Part of the Surface 

 of the Soindle mould be betwixt the End of a Notch 

 and the Hole, one or more Seeds coming betwixt 

 that Surface and the Tongue, might hold it open, and 

 prevent its prefiing againft the Notch, to hold the 

 Seed therein from falling without the Turning of the 

 Wheels. 



This Proportion of Seed is alter'd by the Number 

 of Notches, and by their Depth or Breadth, or by 

 both, b c is the Depth of a Notch, which we call 

 its Side; and is that which takes hold of the Seed, 

 and carries it down thro' the Seed-palTage. The 

 Manner of cutting this is feen by its being a Portion 

 of the Radius A c. The Bottom of a Notch is made 

 in different Forms {a) : As, firlt, it may be convex, 



as 



(a) The convex Form is bed for turning out a great Propor- 

 tion of Seed; becaufe fucli a Bottom may be broader than one of 

 any other Form, in a Notch of the fame Depth and Capacity y 

 -and fuch a Notch, having its Capacity more in Breadth than Depth, 

 will be lefs liable to let fall any Seed without the Turning of 

 the Wheels, than a Notch that is deeper and narrower, except it 

 be very narrow, which it cannot be for throwing out a large Pro- 

 portion of Seed ; for a great Number of Notches cannot have 

 altogether the fame Capacity as a letter Number of the fame 



Depth 



