ON THE PLOUGH. 3

formed very eafily by another inftrument of agriculture, and when land is ploughed for fallow, the more it is broken the worfe. It may be faid indeed, that this board might be applied to the plough conftruéted for a foil that rifes entire, where it would be of fingular ufe in breaking and reducing it. But this is what has never been thought proper to be put in practife: Andindeed it feems very uncertain whether a foil that rifes en- tire, could be broken by any curve of the mould-board, that would not render this machine intolerably hard to draw, from its natural figure, already extremely heavy and difficult to move.

Hitherto I have defcribed the figure of the plough, and explained its manner of operation; I have inveftigated the properties of it; and endeavoured to determine its moft advantageous form: It only remains, that I point out the principles on which the pofi- tion and proportions of its particular parts depend, efpecially thofe of the beam and handles.

The beam is entirely fubfervient to the purpofe of moving the plough; its pofition,

E therefore,