FARM IMPLEMENTS. 83 



Here a second or smaller front plow is attached to ilie 

 plain cylinder plow. By this arrangement the top sod is first 

 cut and thrown into the furrow, where it is completely covered, 

 leaving the plowed surface light and easily worked by the 

 harrow into a mellow seed bed. It gives a general idea of 

 what is known as the Michigan or double mould-board plow. 

 The mould-board is made of a curvature to fit a perfect 

 cylinder, and the plow is named from the principles on which 

 it is constructed. 



The " Conical Plow," invented and made by Solomon Mead, 

 a practical plowman, of New Haven, Connecticut, is another 

 instance of the adaptation of the various parts of the plow to 

 mathematical principles. {Fig. 29.) 



The mould-board is made to fit the frustrum of a cone with the 

 base or larger end forward. A block of wood, rounded ofl:' in 

 the form of a cone, will fit closely to the surface of the mould- 

 board from the highest point to within about two inches <.»f the 

 cutting edge of the wing of the share. The angle of the share, 

 for two or three inches of the cutting edges, is so slight that 

 some inches of the furrow slice are completely separated before 

 it rises much. This gives an easy separation of the furrow 

 slice, since it rises slowly and gradually at first till it reaches a 

 point higher up on the mould-board, where a more abrupt 

 curve hastens it over. {Fig. 30.) 



By this form of the mould- board, the furrows are more 

 thoroughly pulverized and crumbled up, than when the board 

 is made to fit the straight surface of a cylinder. The surface 

 of the board of the conical plow is neither concave nor con- 

 vex in a horizontal plane, so that the friction between the board 

 and the furrow slice is uniform, no greater in one place than 

 another. It cleans, therefore, more readily than a concave 

 board can do, and the wear is evenly distributed over the su: 



