They render the field smooth for the cradle, scythe, and rake, press the earth close about the seed, and secure a more sure and quick germination. On light and sandy lands they are invaluable, and in all cases their use has greatly increased the product. Much benefit is undoubtedly found in compressing the surface of such light soils, by preventing the escape of those gases from the manure so essential to vegetation, and which are so rapidly extracted by the sun and winds.
Great advantage is gained by rolling early in the spring while the ground is yet soft.
Clay lands, by heaving, pull to pieces and displace the roots of grain and grasses sown the previous autumn, and the heavy roller presses the roots and earth together to their proper position, when vegetation goes on again, and thus, in a measure, prevents what is termed winterkilling. 35 represents an approved form constructed wholly of iron, except the tongue and bow, which are of wood. 36 is hand-roller used upon lawns and gardens. Additional weight is supplied by iron weights pivoted as shown to the axle.