History of the Plow. 121 



and the point of its intersection with the line E e determines the 

 height of the npper edge of the working surface of the mould- 

 board from the base. And having thus obtained this height I 

 transfer it on to the line E e, Fig. 5, and from this height I draw 

 the diagonal line F f'^'^ intersecting the division 12 on the line 

 B b twelve inches from the base, and project it to the front end 

 of the plow. The inclination of this line to the base line gives 

 the inclination of the upper edge of the working surface to the 

 base of the plow, its inclination to the plane of the land side 

 having been determined by the line Ff on diagram Fig. 1. The 

 inclination of the line g f^ to the plane of the base has already 

 been determined, and to determine its inclination to the plane of 

 the land side, I delineate on diagram Fig. 1 the arc h of Fig. 6, 

 so that the chord of the arc shall be parallel with the line A a, 

 and intersecting the line B b at the point c, or heel of the mould- 

 board, and so that the line of division 4 shall coincide with the 

 line B b, the convexity of the arc being towards the line A a, 1 

 then draw the diagonal line gf^ from the point g of the plow to 

 the line E e, or third division, and intersecting the line B b at 

 the point of its intersection with the arc 7i. The inclination of 

 this line, gf^, to the plane of the land side, so determined on 

 diagram Fig. 1, I transfer to Fig. 4, which represents a plan view 

 of the mould-board, with the lines projected on a horizontal 

 plane, where it indicates the inclination of that part of the sur- 

 face of the mould-board to the plane of the land side, along the 

 entire length of the mould-board, the inclination thereof to the 

 base having already been defined and represented in Fig. 5. 



"Having, in the manner above described, defined and located 

 the inclination of the surface of the mould-board to the plane of 

 the base and the plane of the land side, along the straight line 

 Ff^'^ or upper edge of the working surface, and along the straight 

 edge, ^/*, from the point of the plow to the third division, it 

 becomes necessary to define the form at certain distances between 

 these two lines sufiiciently near to each other that the workman 

 may practically work down the whole surface of the mould-board. 

 I have found that by lifting the form on the lines at distances of 

 about an inch apart, that the workman can finish the residue of the 

 surface with sufficient accuracy for all practical purposes; but, 

 after the location of certain lines at this distance apart, by the 

 same rules these divisions can be multiplied to an indefinite 

 extent. 



