In clay and other heavy soils, it is necessary after ploughing to
break up the large pieces by means of rollers, and in light soils
to press it together; for these purposes rollers are used, either
with smooth or undulated surfaces, as in the figure; these last form
furrows into which the seed falls, causing it to come up in rows.
Rollers of a lighter kind are used after mowing to level the surface.