( 58 j 
3d. The soc, in its widest part, should be larger 
than the head. It has different shapes in different 
countries. In some is given to it that of an isosceles 
triangle; in others, that of the head of a lance: in 
Biscay, that of a crescent ; and in Poland, of atwo 
pronged fork. But, whatever be its shape, it should 
be well pointed and polished—enter the earth with 
facility, and cut it easily. 
4th. To the mouldboard, some workmen give the 
shape of a prismatic wedge; others make the upper 
part convex, and the lower concave; while many 
make it entirely flat. In stiff soils, the semt cycloid — 
is the form to be preferred, and in loose friable soils 
the semi ellipsis.(1) The iron mouldboards have 
great advantages over the wooden, particularly 
when they, the shear and the soc, form one piece, as 
in the ploughs of Mr. Cook. 
It is a general opinion, that a heavy plough is 
more disadvantageous than a light one ; because the 
draft of the former, being greater, will be more fa- 
tiguing to the cattle; but the experiments of the 
agricultural society in London, establish a contrary 
doctrine, and show, that in light grounds, the labor 
is more easily and better performed, with a heavy, 
than with a light plough. 
5th. The colter is a species of knife inserted in the 
beam, and so placed before the soc, as to cut the sod. 
It is susceptible of being raised or depressed at 
will. 
6th. The handles of the plough ought to be made 
—_——_ 
(1) See Arbuthnot on ploughs. 
