T2 Aétion of the plough in geueral.

row. The firſt of theſe adions is per-

formed by the coulter, the ſecond and a- 7 X?

third by the ſock and moüldboard

jointly. Theſe are to be conſidered in

order. Of the Coulter.

The coulter muÊft be conſidered as a cutting inſtrument, oppoſed to great and varions refiſtances. It muſt be ſharp, that it may cut the more eaûly, and ſtrong, that it may not be broken or bent. Theſe properties cannot be unic- ed, unleſs it is thin and broad. The giving it great ſtrength, by means of great thickneſs, expoſes it to more re- ſiſtance than is neceſlary; whereas, in- creaſing the breadth of the coulter di- miniſhes the reſiſtance, by making it a

fharper wedge,

The

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