Chap. XX. Of the Drill-Boxes. 337 



wards, and narrower upwards-, by which means the 

 Seed is prevented from arching in the Mortife before 

 it defcends to the Notches of the Spindle. And this 

 is the Firfl Ufe of our Bevel; for this Arching might 

 happen in the Mortife, if the Planes of its Sides were 

 parallel to each other-, and would be unavoidable, if 

 their Inclination were downwards, as it is upwards ; 

 but thefe Planes opening downwards, the lower the 

 Seed defcends, the more Room it has to expand •, fa 

 that the very Weight, which would otherwife caufe 

 it to arch and flop, does by means of this Bevel force 

 it to defcend to the Notches, and then it is fafe from 

 all manner of Danger of flopping. The Ends of 

 the Mortife are at fuch a great Diftance from each 

 other, and the Cover io very thin, as to lie aimofb 

 even with the upper Part of the Spindle, that the 

 Seed can never form an Arch that way; or, if it did, 

 the continual Motion of the Tongue would immedi- 

 ately break it down at the Fore-end of the Mortife. 



The Second Ufe of this Bevel is, that it gives 

 room for the Tongue to be in the fame manner bevel, 

 tho' in a lefs Degree : By this means, the Seed cannot 

 by any Impediment be flopped in its oblique Defcent 

 to the Notches, from the Fore-end, and all that other 

 Length of the Mortife, along and upon the Surface 

 of the Tongue. 



But if the Mortife had not this, Bevel, the Tongue 

 could not have it ; for then either the upper Surface 

 of the Tongue mud have no Bevel at all, which 

 would deftroy the Two empty Triangles which ought 

 to be on its Sides ; or elfe it mufl have a Bevel the 

 contrary Way (i. e. a Bevel reverfed), and be narrower 

 downwards than upwards, which would caufe the 

 Seed to arch thereon, and hinder its free Defcent to 

 the Notches. 



A Third great Ufe of this Bevel is, that, befides 

 the Bevel of the Tongue aforementioned, it gives 

 place for Two empty Triangles, one on each Side the 



Tongue, 



