bee i te ae

force that pulls it adts. The neceffity of its having no inclination is obvious; for, had the direction of the jplough not coin- cided with the dire€tion of the force, but pointed either to the right or left, the con- ftant tendency of the inclination muft have been, to turn the plough from the right di- rection, either toward the furrow or the

firm ground. And this is the reafon why°

the plough is a half-wedge*. By its being a half-wedge, the direCtion of it coincides exactly with the direGtion of the force; whereas, had it been greater than a half- wedge, its direction muft have pointed to

the

* AD, fig. IL is the direction of the plough, or of the force that moves it. AB is the dire€tion of the plough, or half-wedge, according to note firft; and thefe two in this cafe coincide. Were the plough greater than a half-wedge, as ABC, fig. III. then, fuppofing ABE the direétion of the force, or the line of the furrow, DBF will be the natural di- rection of the plough tending to the left of the line of the force. Were the plough lefs than a half-wedge, as DBC, fig. IV. DBF being the line of force, ABE will be the natural dire€tion of the plough to the right of the line of force.