a place in which sawing is carried on by help of wind, water, or steam power.

The principal part of the saw-mill is the frame-saw used for cutting up logs, represented in figures 8 and 9. It consists of a frame AA moving between two vertical cheeks. In this frame the saw-webs are stretched according to the nature of the work to be done; these must be fitted truly parallel to the line of motion, and at such distances from each other as to produce planks of the desired thickness.

This frame AA is moved upwards and downwards by means of a crank attached to the machinery, and acting through the connecting rod B; the saws cut while descending. The log to be operated on is fixed in a long frame CC, which is brought forward by means of a pinion fixed to the axis of the ratchet-wheel D. The feed, as it is called, is obtained in this way; the end E of the lever EFG is attached to the saw-frame, so as to oscillate with it, thus causing the arm FG to oscillate also; this arm FG has a row of holes in it for attaching the hook H, which, acting on the ratchet-wheel, brings it round by the distance of one or more teeth at each descent of the saw; the number

of teeth and consequent feed being regulated by the effective length of the arm FG.

The log passes over a support K as close to the saws as possible, and is kept in its place by fences or rollers LL acting on its sides; it is also prevented from rising by two struts M and N, hanging from the frame-work.

Circular, veneer, and ribbon saws belong naturally to the saw-mill; they have been sufficiently described in the preceding article.

In the saw-mill we often find other kinds of work carried on. Flooring deals and lining boards, after having been roughly shaped by the saw, are dressed to the required breadth and thickness, planed smooth, feathered and grooved on a machine in which planes, saws, and adzes are combined. Battens, too, have their tenons and mortices dressed by appropriate machinery, and the navies of cartwheels have their spoke-holes neatly cut out by a combination of augers and chisels; but these are additions to the saw-mill proper.