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BOOK VIII.

lower part is a palm wide and thick ; then gradually the upper part becomesnarrower and thinner, so that at the top it is three digits and a half wide andtwo thick. It is bored through at the place where the angles have beensomewhat cut away; the hole is three digits long and one wide, and is onedigit’s distance from the top. There are some who make that part of thehead which is enclosed in the stem, barbed and grooved, in order that whenthe hooks have been fixed into the stem and wedges fitted to the grooves,it may remain tightly fixed, especially when it is also held with two quad-rangular iron bands. Some divide the cam-shaft with a compass into sixsides, others into nine ; it is better for it to be divided into twelve sides, inorder that successively one side may contain a cam and the next be without one.

The water-wheel is entirely enclosed under a quadrangular box, in caseeither the deep snows or ice in winter, or storms, may impede its running andits turning around. The joints in the planks are stopped all around withmoss. The cover, however, has one opening, through which there passesa race bringing down water which, dropping on the buckets of the wheel,turns it round, and flows out again in the lower race under the box. Thespokes of the water-wheel are not infrequently mortised into the middle of

A—Box. Although the upper part is not open, it is shown open here, that theWHEEL MAY BE SEEN. B—WHEEL. C—CAM-SHAFT. D—STAMPS.

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