VITRUVIUS. 
246 
in thi is contained an axs(E), having at its upper end an iron dovetail (P), which is inlerted 
in the mill tone (0): thus the teeth of the tympanum (B), that is included on the asis, 
impellig the teeth of the horizontal tympanum (D), cause the rotation of the mil- fone, 
to which the suspended hopper (H) (infundibulum) furnishes the grain; and by the same 
rotation the meal is ejected. 
CHAPTER 
XI. 
Of the Cochlea. 
Fig. LXXXV. 
HERE is a machine of the cocblea kind, that draws a great quantity of 
Fig. LXXXVI. 
water, but does not raise it so high as the wheels; it is constructed thus: A 
beam (A) is provided, being as many digits in thickness as it has feet in length; and this is 
made round. At the ends (A) the circle (ACE) is divided with compasses either into four 
quarters, or eight octants, drawing lines; and these lines are to be so disposed, that when the 
beam is erected level on a plain, both ends of the (respective) lines (AA, BB, CC, DD, EE) 
may correspond in the perpendicular. After this, from one end to the other transverse lines 
(F) are drawn, in such a manner that, whatever the measure (AB) of the eighth part of the 
round of the beam may be, so large must be the space (FF) between them, latitudinally. 
Thus both circumferently and longitudinally the spaces will be equal; and these lines, at the 
places where they are described, passing those that are lengthways, make interlections, and 
those intersections are marked by points. This being exactly described, a thin ruler, cut 
from willow or agnus castus, being anointed with liquid pitch, is fixed at the first point of 
intersection (A), from whence it is laid obliquely to the next intersection (2) of the longi- 
tudinal and circumferent lines; and so circumvolving, and passing through every point (3, 4, 5) 
in order, it is applied to every intersection, till it arrives and is fixed at that line which is on the 
eighth point (8) from the first, wherein the prior part of it was fixed: thus, as much as it passes 
obliquely through the spaces and eight points, so much it advances toward the eighth point in 
longitude. In the same manner, through all the spaces of longitude and circumference, 
fixing rulers obliquely at every intersection, and winding through the eight divisions of the 
thickness, they form channels, and an exact imitation of the natural cochlea. On the other 
tracts, other rulers, also anointed with liquid pitch, are fixed, and added till the whole thick¬ 
neis becomes equal to the eighth part of the length. Then upon these the planks (G) are