74 Bepobt on Trials of Plows. 



furrow slice is disposed to assume, lifts the furrow slice at a sin- 

 gle point, and that in the middle instead of being equally applied 

 throughout the entire operation. 



"In order to meet and remedy the inconveniences arising from 

 this form of structure, I form my mould-board into a different 

 shape, and instead of working the moulding part or face of the 

 mould-board to straight lines, my improvement is to work it to 

 circular or sphere lines. By repeated experiments I have ascer- 

 tained that in one direction, viz.: from a, Plate VI, fig. 4, inclin- 

 ing to the back part, d, the circle or segment of the mould-board, 

 to which the mould-board is wrought, should have about three 

 times the radius of the smaller segments represented b^^ the lines 

 lettered c c, &c., the former being thirty-six inches, the latter 

 twelve inches. In order then to shape the moulding part, or the 

 face of the mould-board, having obtained a suitable block, I begin 

 by laying off the bottom (Fig. 3), and (Fig. 4) by circular or 

 spheric lines at a a a. If I intend to construct a plow of a 

 proper size to cut and turn a twelve inch furrow, I strike this 

 segment of a circle of thirty-six inches radius (Fig. 1), and at 

 twenty-four inches back from the point c at right angles with the 

 land side and twelve inches from the land side; the circle will 

 intersect the angle line; this circle is extended out from the land 

 side; I then work the block to fit the same segment, inclined 

 from a (Fig. 4) at the point of the share, to a at a perpendicular 

 raised twelve inches from the horizon, with the circle extended 

 in toward the land side; then having wrought to the shape of 

 these two lines, I apply the circular part of the smaller segment 

 (Fig. 2) and work the face of the mould-board, until that segment 

 will have an equal bearing on all parts, corresponding with the 

 cross lines c c c, &c., which if produced would all terminate in 

 a point at d, Avhich is about thirty-six inches from the perpendic- 

 ular, where the line a a crosses the line d b; this being worked 

 off uniformly, forms a section of an oxydromic or spiral curve, 

 and when applied to practice is found to fit or embrace every 

 part of the furrow slice far more than any other shaped plow. 

 The plow may be made larger or smaller, suited to deep or shal- 

 low plowing, by enlarging or diminishing the radii of the seg- 

 ments which it is wrought by. Believing that this mode of 

 shaping the moulding part or face of the mould-board is an origi- 

 nal invention of my own, not heretofore known or used, and that 

 it is a most important improvement in the shape of the plow, I 



