SECRETARY'S REPORT. 55 



to resort to an indirect action to arrive at the desired effect. This 

 indirect action is accomplished through the medium of an angulajr 

 frame-work, consisting of the beam and the body of the plough, so 

 strongly connected together as to form an unyielding structure. The 

 effect of the motive force applied to the frame-work at the point h, 

 and in the line of b to f, produces the same results as if c J were firmly 

 connected by a bar in the position of the line c to h, or as if that bar 

 alone were employed. 



"The average length of the trace chains being 10 feet, including all 

 that intervenes between the clevis of the plow at h, and the horse's 

 shoulders, let that distance be set off in the direction h tof; and the 

 average height at the horse's shoulders where the chains are attached, 

 being about 4 feet 2 inches, let the point f be fixed at that height 

 above the base-line d e. Draw the line from f to c, which is the di- 

 rection of the line of draught acting upon the assumed centre of 

 resistance, c ; and if the jjlough is in proper trim, it will coincide 

 also with the ring of the clevis; e cf being the angle draught, and 

 equal to 20°. It will be readily perceived, that with the same length 

 of hames, the angle e c f is invariable ; and if the plough has a 

 tendency to rise at the heel, or run on the point, under this arrange- 

 ment, it indicates that the ring at b is too high in the clevis. Shift- 

 ing the ring one or more holes downward, will bring the plough to 

 work evenly upon the base of the landside, or work flat. 



" If the plough has a tendency to rise at the point of the share, the 

 ring b is too low, and must be moved by raising it one or more holes in 

 the clevis. If a pair of taller horses be harnessed to the plough, the 

 draught chains, depth of furrow, and soil (and, by consequence, the 

 point of resistance c,) remaining the same, we should have the pointy 

 raised, suppose toy ; by drawing the liney to c, we have e c f as 

 the angle of draught, which Avill now be 22°, and the ring will be 

 found to be below the line of draft/' c; and if the draft chains were 

 applied at b, in the direction /' b, the plough would have a tendency 

 to rise at the point of the share, by the action of that law of forces 

 which obliges the line of draught to coincide with the line which 

 passes through or to the centre of resistance ; hence the ring b would 

 be found to rise to b\ which would raise the point of the share out 

 of its proper direction. To rectify this, the ring must be raised in 

 the clevis by a space equalling that between b and b ', causing it to 

 coincide with the true line of draught, which would again bring the 

 plough to work evenly on the base of the landside, and run fiat. 



" The foregoing principles are substantially such as are adopted by 

 the most experienced ploughmen, and if properly applied, will not 



