202

BOOK VI.

b

C^*==

mm

m-m

W"* '

’mm

i..—

e>«33»’

;;0v

SU»&>$SSi8&j53g&.

r:.-=3\

V-w

:m'

r_’Rs™

>Ma\.

A— Projecting mouth of conduit. B— Planks fixed to the mouth of the conduit

WHICH DOES NOT PROJECT.

feet high and three feet in diameter, bound with wooden hoops ; it has asquare blow-hole always open, which catches the breezes and guides themdown either by a pipe into a conduit or by many pipes into the shaft. Tothe top of the upper pipe is attached a circular table as thick asthe bottom of the barrel, but of a little less diameter, so that the barrel may beturned around on it ; the pipe projects out of the table and is fixed in around opening in the centre of the bottom of the barrel. To the end of thepipe a perpendicular axle is fixed which runs through the centre of the barrelinto a hole in the cover, in which it is fastened, in the same way as at thebottom. Around this fixed axle and the table on the pipe, the movablebarrel is easily turned by a zephyr, or much more by a wind, which governthe wing on it. This wing is made of thin boards and fixed to the upperpart of the barrel on the side furthest away from the blow-hole ; this, as Ihave said, is square and always open. The wind, from whatever quarter of