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48 A N BS: AGy Aa though, in particular cafes, it will be higher or lower according as the refiftence is great- er on the furface, or at the bottom of the furrow: And this is the reafon why the fame plough, though made with the greateft exactnefs, will go too deep in fome cafes, and in others too fhallow. It was becaufe the fituation of this point may be nearly gueiled at, that I fuppofed it formerly actu- ally found, and applied it to the determina- tion of the length of the beam.

Now, in fome cafes, the greater handle is not ftreight, and does not go direétly to- wards the center, but is curved downwards, and joined to the hinder part of the head, or fhare: In others, it is almoft ftreight, and feems to go direétly to the center. The on- ly circumftance that determines the fuperi- ority of one of thefe forms above the other, is its being a longer lever than the other; that is, the diftance of the extremity of the one from the center being greater than that of the other; for, according as this diftance is greater, equal, or lefs, their powers will

“be fo likewife. It muft not be imagined,

becaufe