136 POWER AND THE PLOW 



more closely than any other of that time, the modern imple- 

 ment, but to the old Berkshire plow. This plow had a pair of 

 wheels to support the beam and a clumsy device by means of 

 which front of latter could be elevated or depressed to change 

 the depth of plowing. The point was of iron, also the ground 

 wrest, which in later plows has been superseded by the con- 

 tinuation of the point into a share. The ground wrest was 

 placed at an angle to the landside in the horizontal plane, 

 like the edge of a modern share, but stood nearly perpendicular 

 to the bottom of the furrow. It constituted the wearing plate 

 and supported the wooden moldboard. The latter, only 

 slightly curved, joined the ground wrest at an angle which was 

 sufficient to invert the furrow slice. In shape and ease of 

 draft it was inferior to the Rotherham plow, but in its four- 

 knife coulters it possessed the capacity for pulverizing the soil 

 better than any previously known tillage implement, and this 

 outweighed all other considerations with Jethro Tull. Three 

 of these coulters were mortised into the beam ahead of the 

 plow point, and the fourth about midway between the point 

 and the forepart of the moldboard. Each of the last three 

 was an equal distance to the left and rear of the one ahead, 

 and inclined a trifle more from the perpendicular. 



TulPs argument in favor of the plow is substantially as 

 follows: "It divides the land more completely, affording 

 greater access to air and moisture. The furrow being cut into 

 four parts, it will have four times the superfices that it would 

 have without the coulter cuts; but this is not all. It is more 

 divided crossways, viz. : The ground wrest presses and breaks 

 the lower (or right hand) quarter; the other three quarters, in 

 rising and coming over the earth board, must make a crooked 

 line about a fourth longer than the straight one they made 

 before being moved; therefore, their thinness not being able 

 to hold them together, they are broken into many more pieces 

 for want of tenacity to extend to a longer line. This is con- 

 trary to a whole furrow, whose great breadth enables it to 



