142 Mechanical and Technical Processes. Materials
stand on the lower yard and push the upper yard and sail up
into place so that the function of the numerous halyards was
merely to hold them up and not to hoist them. The rudders
of the ancient ships, if of the traditional papyrus type, consisted
FIG. 19. Steering gear of the trading ships of Queen Hatshepsut,
XVTIIth Dynasty. Temple of El-Deir el-Bahari.
of two fixed paddles, one on either side of the stern, which could
be rotated by a small lever fixed near the tops (Fig. 19). Other
ships had a single paddle—with a similar method of rotation—
reaching far astern.
The subject of the ancient methods of shaping stone for use
in various handicrafts has been extensively studied, although
several problems remain open to controversy. Egypt is prolific
in stone, which may be divided for the purpose of consideration
of the methods of working it into hard and soft varieties.
The hard rocks are the diorites, the dolerites, the schists, the