Line of Draught of Plows. 183 



pounds), and no sensible difference was observed in a range of angles 

 varying from 45 to 70 degrees. This coulter, having been 

 removed, the plow was drawn along the surface of the field, when 

 the ploAv indicated eight stones (112 pounds), the usual draught 

 of a plow on the surface. 



"Another well-trimmed ploAV Avas at work in the same ridge, 

 taking a furrow ten by seven inches, and its draught was also 

 350 pounds. The furrow thus taken produced, of course, a slice of 

 very rough plowmauship; and though it exhi])ited, by a negative, 

 the essential use of the coulter — the clean cutting of the slice 

 from the solid ground — the whole question of the operation and 

 working efiects of the coulter are thus placed in a very anomolous 

 position.'- 



If the experiment of Mr. Stephens is reliable, it would seem 

 that the extreme care which plowmakers have taken to adjust the 

 coulter accurately to the various parts of the plow is quite unnec- 

 essary, and that the reasons given for their respective plans rest 

 upon a purely imaginary foundation. 



Farmers having observed that a drawing cut requires less power 

 to separate a solid body than a direct cut by pressure — as the saw 

 cuts easier than the chisel — have imagined that they obtained 

 such a drawing cut by giving a long rake to the coulter; but on 

 looking closely at the matter it will be seen that this gives no 

 drawing action whatever to the cut of the coulter. 



There is no upward and downward motion, no reciprocating 

 action as when we draw a knife across a loaf of bread, but it is 

 simply a cut efiected by horizontal pressure operating through 

 the whole length of the blade just as when the edge of a chisel is 

 pressed into wood by the blow of a mallett. There is therefore 

 no economy of power by inserting the coulter at a high angle 

 with the sole, the resistance so far as the splitting of homogeneous 

 earth is concerned is precisely the same whether the angle is 45 

 deg. or 80 deg. 



Nevertheless, in practice, arising from other causes than the 

 splitting of the earth, there are great advantages to be derived 

 from a variation of the angle between 45 deg. and 85 deg., and 

 incidentally there is a considerable saving of power. 



Thus in plowing stubble land which is very foul the dry grass 

 and butts of the straw would collect transversely on the edge of 

 the coulter. In this case the draft is frequently increased by 150 

 pound.s; by giving it it a long rake the stubble is slioved upward 



