2165. The movable rafter-trellis consists of a rod bent parallel to the roof, with horizontal studs or rods, extending from 6 to 10 inches on each side, containing two collateral wires, the rod itself forming the third. This rod is hinged, or moves in an eye or loop, fixed either immediately above the plate of the parapet, or near the top of the front glass. It terminates within 1 or 2 feet of the back wall, and is suspended from, the roof by two or more pieces of chain attached to the studs, the links of which are put on hooks fixed to proper parts of the roof. Their advantage is chiefly in the case of very early forcing, when they can be let down 2 or 3 feet from the glass, and thus is lessened the risk of injury from frost. A whole sheet or tegument of trellis, if desirable, may be lowered and raised on the same general plan. (See the details, Hort. Trans., vol. iii.) Rafter-trellises are in general use only for such houses as are not chiefly devoted to vines; such as pineries, peach-houses, and sometimes greenhouses.