126 



MECHANICS. 



to hold, on account of the side pressure. Tlie character of 

 this kind of plow may be quickly perceived by simply ex- 

 amining the mould-board after use ; the scratches, instead 

 of passing around horizontally, as they should do, are seen 

 to shoot upward across the face and disappear at the top. 



Instead of this form, the point should be long and acute, 

 and the mould-board so shaped as to begin to raise the 



left side of the sod 

 the moment it is cut, 

 and before the right 

 side is yet reached 

 by the cutting edge. 

 This turning motion 

 being continued, the 

 EdbrooTc's Shtbble Plow, or Deep Tiller. gQ^ |g inverted bv be- 



ing scarcely lifted from its bed; and the pressure Avhich 

 turns it being opposite to the pressure of the land-side, an 

 equilibrium of these two pressures is maintained, and the 

 plowman is not compelled to bear constantly to the right 

 to keep the plow in its place. 



There is, hoAvever, an excej^tion, in deep or trench plow- 

 ing, where it becomes necessary to throw the earth from 

 the bottom of a furrow to the top of the inverted sod. A 

 plow of this kind is represented in Fig. 133, which shows 

 Holbrook's deep tiller for stubble land, capable of plowing 

 Fig. lai. a furrow a foot deep, and 



elevating the earth, which 

 passes lengthwise over the 

 mould-board. A similar 

 Crested Furrow-siicer. form must bo adopted for 



the rear mould-board of the Double Michigan Plow, so 

 that the lower earth of the furrow may be thrown on 

 the sod inverted by the first or skim-plow. 



The share should also be so placed as to cut the slice 

 at equal thicknesses on both sides. Some plows are made 



