The origin of the ceiling as distinguished from the underside of the floor, appears to be found late in the fifteenth century, or early in the sixteenth, when the practice was introduced of covering the lower sides of the floor joists with flat boarding and dividing the level surface into panels by means of applied mouldings. Such a ceiling is found in the Bede House at Lyddington in Rutland, formerly a country house of the Bishops of Lincoln (Fig. 89). The junction of the ribs was sometimes ornamented with a carved boss such as is shown in Fig. 90, also from a house in Lavenham. This simple method of treating ceilings was developed in course of time into the elaborate plasterwork of Elizabethan houses. The room at Lyddington has a very remarkable wood cornice fashioned after the manner of the fan tracery prevalent at the end of the fifteenth century (Fig. 91). But this kind of ornament was not at all general, and it may be doubted whether any other instance of it can be cited. [Illustration: 91. Lyddington Bede House. Traceried Cornice in Wood.] * * * * * STAIRCASES.--There is little to be said about mediæval staircases. They were almost universally of the corkscrew type, the steps winding round a central newel, as at Tattershall Castle (Fig. 43). There was but little opportunity for embellishment, and accordingly none is to be found, the nearest approach being the treatment of the stone handrail already shown in Fig. 44. The steps were usually of stone, the undersides being sloped off to afford as much head room as possible below them. In some instances when the summit of the staircase was reached, the roof of the enclosure was vaulted with some attention to appearances, but beyond this the ornamental treatment did not go. There are a few instances of these staircases being vaulted all the way up in brick, the steps themselves being then built up on the top of the vaulting. This was a clever and ingenious piece of brickwork, but was not especially ornamental. Indeed we have to wait until the time of Elizabeth for any display of fancy in the treatment of staircases; up to that time they were strictly utilitarian in character. * * * * *