4io APPENDIX. 



of the Mortife* by whick muft be made Two in Paft- 

 bpard. Fig. 10. in Plate 2. and Fig. 9. in Plate 3. 

 are the Two Ends of it. 



The Cover that prevents the Wheat from falling 

 down on the hinder Side of the Spindle, is one intire 

 Piece of Brafs, which is marked B in Fig. 3. of 

 Plate 3. but the Shape of it, with its Hole whereby 

 it is held in by a Screw, is only feen in the Side, 

 Fig. 3. of Plate 2. and there defcribed by pricked 

 Lines ; and by pricking through them, the Shape of 

 the End of the Cover may be taken, which Cover 

 k of the fame Shape from End to End. 



The Joyner who cannot by thefe Additions, and 

 the Explanations of the Plates, make thefe Drills in 

 Wood, doth not deferve the Name of a Workman. 



When he has once made them whole, he can eafily 

 make them in Halves like Fig. 8. in Plate 2. 



By thefe Halves the Founder will make his Moulds 

 proper for calling them in the bed Brafs. But in 

 thefe Halves for Cafting, there mint be no other 

 Holes, but the great Holes, and the Hole for the 

 Setting-fcrew. 



The great Hole in the Mould muft be largeft at E, 

 in Fig. 9. Plate 2. and lefler in the Infide in Fig. 8. 

 for as it muft be of a conical Shape for making the 

 Core, if it fhould be caft bigger within, when the 

 Whitefmith bores it (as he muft) to an exact Cy- 

 linder, the End E would be in Danger of burfting by 

 the Force of the Boring, as it is much thinner than in 

 the Mortife. And befides this, if there mould be any 

 little Flaw in the Edges of the Hole within the Mor- 

 tife (which theFounder muft avoid as much aspofiible), 

 it may perhaps be bored out by means of the Hole's 

 being lefs there. The Hole muft be fomething lefs in 

 the Mould than its proper Size, even where it is largeft ; 

 elfe it may happen, that in boring it to a true Cylin- 

 der it may become too big. And I believe, in the 

 Cooling of the Brafs, the Hole grows bigger as the 

 Spindle grows lefs. For 



