an iron or brass joint, on which doors, lids, gates, and shutters swing, fold, open, or shut up. The common form of a hinge is two leaves, perforated with holes for screws, and furnished each with projecting segments of a hollow cylinder, which fit into each other, and are secured by means of a central pin. This joint is applied by screwing one leaf to the door and the other to the doorpost. Hinges for gates and out-house doors are made in the form of the letter T; they are called cross-garnets. They are sometimes made with long straps and hooks to fix in the stiles, so that the gate or door may be lifted off its hinges when required. Hinges for the doors of rooms are called butts, and are of various kinds. Hinges for shutters are termed back-flaps. Similar kinds are used for the joints of bedsteads, and for Pembroke and other tables. H and H hinges, so called from their form, are in common use. Improved forms of hinges have been made the subjects of numerous patents. Collinge's hinge, improved by Redmund, has its bearing pin in the form of a conical stem, with a sharper conical top corresponding with the bearing socket, and over this is a hollow cap containing oil, which enables the two surfaces to work with great truth and freedom. Redmund's hinges or rising-buts have the hollow cylinder which is attached to the leaves divided, not at right angles to the pin, as is usual, but by spiral or helical lines, so that on opening the door it is lifted from the floor by the rubbing surfaces of the hinge moving upwards in a helical line, so that when the door is left to itself, its weight causes it to descend by the inclined rubbing surfaces, and thus to close itself. The door can, however, be made to stand wide open by cutting away a portion of the helical curves so as to form two horizontal planes, which become opposed to each other when the door is opened sufficiently to form a right angle with its position when shut. Hence the door will close of itself, when it is not pushed open more than 50° or 60°; but it will stand wide open if pushed to 90°. Spring-hinges for the swing-doors of public offices, &c., made to open either way, and to return quickly to their shut-to position, are numerous. In Whitechurch's hinge, doors, windows, &c., can be opened either to the right or left hand. Nettlefold's hinge for book-cases allows the door to fold back quite level with the book-shelves, so that books close to the hinge can be taken out and put in with facility. There are also numerous patents for casting iron and brass hinges, as well as for stamping the same.