ugh a mctalHc sieve sufficiently fine to retain the foreign substances. This is fixed to one of the boxes of the machine ; the clay is caused by the compression to pass through it, and is afterwards placed in the Fig. 564. — Piston Expression Machine, worked by Hand (Whitehead). other box, whence… … Fig. 565. — Piston Expression Machine, worked by Steam (Whitehead). worked by cog-wheels (Fig. 565), which are so arranged that the return, that is the waste movement is made at great speed. As there is no lid to be raised before introducing the clay, the pro- duction is increased. The machine is…
