114 Report on Trtals of Plows. 



a guide line. The lines v p and v u, both being in the surface of 

 the board, the one where the furrow slice is nearly horizontal, 

 and the other where it is perpendicular, the point, v. Fig. 69, 

 I take as a radiating point to u b' c' jp. A straight edge is to lie 

 in each of these radiating lines so as to fit the actual mould-board. 



" The same figure also exhibits another series of lines which lie 

 in the surface of the board. These are parallel to the forward 

 part of the base, u s, of the board, and touch the curve, u b c p, 

 and the perpendicuhir, o ]). They are also fitted by a straight 

 edge. The angle formed by the base of the land side and the 

 line li s is about 37| degrees. The triangular space, a' s m, repre- 

 sents the heel of the mould-board, which is so formed as to cause 

 it to lift or carry up the furrow slice to the top of that of the 

 forward plow, which is from three to three and a half inches. 

 The form of this part is shown in Fig. 69, b i s, which is an end 

 view of the heel, looking at it from the rear end of the plow. 

 The line a s is formed by the termination of the curving out of the 

 mould-board as seen at a', Fig. 69, b is; the part a' in the same 

 figure being a vertical continuation of the body of the mould- 

 board down to the sole, by which particular form this j^art is 

 removed entirely out of the way of the furrow slice of the forward 

 jjlow. The slice cut off by the fore plow may be about two and 

 a half or three inches in thickness, and it is turned over by it 

 into the furrow last made. 



"Fig. 9 is a left-hand view of the mould-board of the forward 

 plow, separate from the share and land side. E, Fig. 12 is the 

 share seen in place in Figs. 16 and 17. 



"Fig. 14 is the plan of the length and width of this plow cor- 

 responding to Fig. 68 of the hind plow. 



"Fig. 15 is a right-hand view of the mould-board, share and 

 coulter as combined for use. 



" It wall be seen on inspection that the curve of the mould- 

 board forms an irregular conical fioure, the larger end beino" 

 directed forward." 



In October, 1839, Samuel Witherow, of Gett3'sburg, and 

 David Pierce, of Philadelphia, took out a patent Avhich was truly 

 novel. We have not been able to ascertain that it ever got into 

 general use, but it certainly seems worthy of a thorough trial. 

 The following extract from the specification will show the prin- 

 ciple upon which it was founded very clearly: 



" It is a princi])le resting upon mathematical dcm uistration that 



