6o A History of Art in Ancient Egypt. in the groove at the side the cylinder could be made to revolve, and the curtain would thus be easily drawn up and down. These curious forms are thus at once accounted for if we refer them to the wooden structures which were once plentiful but have now- disappeared. Nothing could be more difficult than to find an explanation of them in fornis appropriate to stone or granite. Of what use could such a cylinder be if carried out in either of those i»|l^il!i!;'lf . Fig. 35. — Door of a tomb at Sakkarah ; drawn by Bourgoin. materials ? It could not revolve, and the deep lateral grooves, which have such an obvious use in a wooden building, would be purposeless. We find these features repeated in a rectangular stele from the fourth dynasty, which we reproduce on page 61. In Fig. 37 we give some of its details upon a larger scale. The upper part of this stele displays two motives which will be recognised at the first glance as borrowed from carpentry. The first of these is the
