54 Various Modes of Planting the Potato, 
soil. By a repetition of the same process, in a direction 
across that formerly taken, another 38 or 4 inches may 
be gained. JI shall not attempt to describe the subsoil 
plough, except in very general terms. 
It consists of an iron beam, made of two wrought iron 
bars, kept at a certain distance apart by means of intervening — 
cast iron plates, the whole being carefully rivetted together. 
Through the interval between these bars are passed the iron 
standards from the axles of two pairs of wheels,—also the 
strong coulter and share which breaks up the ground ; and as 
these standards and coulter can be moved up or down so as 
to bring the beam as near or as far from the axle as may be 
wished, or to raise or lower the coulter, it is evident that, 
within certain limits, the edge or working part of the latter 
may be brought as far below the wheel as may be required ; 
and as these wheels run at the bottom of the furrow made 
by an ordinary plough, the subsoil coulter may be made to 
stir the ground to any reasonable depth. 
The plough did its work most effectually : with two horses 
it worked its way through the hard subsoil quite as fast as 
the leading ordinary plough could move, though the work, it 
must be allowed, was harder by far. It was found desirable 
to spell the horses, giving them turn about in the ordinary 
and im the subsoil plough. 
When stones or roots were met with they were thrown 
out easily ; and while the action on the subsoil was generally 
to crumble it up into fine particles, it occasionally, when the 
ground was very hard, turned up a large lump, without, how- 
ever, bringing it to the surface. Further experience of the 
behaviour of the plough has led me to think it desirable-to 
strengthen both the upright standards, from the axle and the 
coulter, by thickening them nearly a quarter of aninch. I 
have found that in hard stony ground both these are apt to 
