When the cage arrives at the surface, or rather the platform forming the working top above the mouth of the pit, it is received upon the keeps, a pair of hinged gratings which are kept in an inclined position over the pit-top by counterbalance weights, so that they are pushed aside to allow the cage to pass upwards, but fall back and receive it when the engine is reversed.
The principal faade of the temple is filled in one, two or three compartments with hinged doors, variously ornamented and folding outwards, sometimes in double folds.
The mould is in two, pieces hinged together; it is heated and the inner surface is rubbed over with finely powdered plumbago.
In this figure the rod a, b, hinged at x, represents the wing.
In Germany and America twoand three-hinged arches of masonry and concrete have been built, up to 150 ft.