The second machine of this genus turns the blowing wind into a shaft
through a long box-shaped conduit, which is made of as many lengths of
planks, joined together, as the depth of the shaft requires ; the joints are
smeared with fat, glutinous clay moistened with water. The mouth of this conduit either projects out of the shaft to a height of three or four feet, or it does
not project ; if it projects, it is shaped like a rectangular funnel, broader and
wider at the top than the conduit itself, that it may the more easily gather
the wind ; if it does not project, it is not broader than the conduit, but
planks are fixed to it away from the direction in which the wind is blowing,
which catch the wind and force it into the conduit.
The third of this genus of machine is made of a pipe or pipes and
a barrel. Above the uppermost pipe there is erected a wooden barrel, four
