1813. Screens are used in gardening for fining or sorting earths, gravel, or tanner's bark. The mould-screen (fig 446.) is a wire frame with a jointed fulcrum, by which it can be placed sloping to any required degree: its use is to separate stones and coarser particles from mould, either in trenching over ground intended for bulbous or other tender and succulent roots, or in turning over compost-heaps. The soil must be well broken with the spade before it is thrown on the screen; and it is in vain attempting to use the utensil unless the earth is dry.