DESCRIPTION OF a MOULD-BOARD. 319 



the faw on the ill fcribe, at what was the bottom edge of 

 the left fide, and cut in, guiding the inftrument at both 

 ends by the fcribe, till it has approached within an inch, 

 or any other diftance according to the thicknefs you choofe, 

 of the face. Then cut in like manner all the other fcribes, 

 and with the adze dub out the fawed parts, and the mould- 

 board is done. It is to be made faft to the plough by refl- 

 ing the toe in the hinder edge of the wing, which muft 

 be made double like a comb-cafe, to receive and proteift 

 the fore end of the mould-board. Then pafs a fcrew 

 through the mould-board and helve of the ploughfhare 

 where they touch each other, and two others through the 

 tail-piece of the mould-board and right handle of the 

 plough, and cut off fo much of the tail-piece as projeds 

 behind the handle, diagonally, and the whole is done. 



1 have defcribed this operation in its funplefl mode, that 

 it might be the more eafily underflood. But, in pradice, 

 I have found fome other modifications of it advantageous. 

 Thus, inftead of firft forming my block as a. b. c. d. 

 Fig. 7. where a. b.'\% 12 inches, and the angle at b, a right 

 one, I cut a wedge-like piece b. c. e. off of the bottom 

 through the whole length of the block, b. e. being equal 

 to the thicknefs of the bar of the (hare (fuppofe i-\ inches) 

 becaufe the face of the wing declining from the top of 

 the bar to the ground, were the block laid on the fhare, 

 without an equivalent bevil at its bottom, the lide a, b. 

 would decline from the perpendicular, and a. d. from its 

 horizontal pofition. Again, inftead of leaving the top of 

 the block 13^ inches wide from m. to n. Fig. 8. I cut a 

 wedge from the right fide n. k. i c. p. ti. i^ inches thick 

 at top and tapering to nothing at bottom ; becaufe I 

 find that the tail-piece, being by this means made ob- 

 lique, as c. i. inftead of ^. /. is brought more advan- 

 tageoufly to the fide of the handle. The firft fuper- 

 ficial diagonal is eonfequently brought from /«. to c. and 



not 



