throw of the crank is cut out, and a fracture is very generally found to take place in this web. The connecting rod should be arranged to take hold of the saw frames by means of rods on either side at about the centre of same, as strength and ease in working are gained, and less depth of foundation is requisite. As regards the feeding arrangements, they must of course be adapted to circumstances. Top pressurerollers for deal or flitch cutting should work independently of one another, so that two pieces of unequal depth can be sawn at the same time. The bearings in which the swing frame works should be adjustable, and by preference made of phosphor bronze. A very good plan is to have an opening in either side of the uprights, and the bearings fixed nearly flush with the outside of the frame; they are thus easily got at for repairs, lubrication, &c. When frames are run at high speeds, the connecting-rod bearings should be of phosphor bronze, and especial care should be taken as to their lubrication, as the friction is very considerable. The cross heads should be forged in the solid, of best fagoted scrap-iron. We purpose noticing the buckling, sharpening, and setting the saws elsewhere.

Our illustration (fig. 7) represents an improved horizontal single-blade timber frame, from the designs of Messrs. Worssam and Co., London. It is especially adapted for the use of those cutting choice and valuable woods into thin boards, where it is necessary to examine the soundness of each board as cut; it is also useful for cutting crooked or irregular timber. The timber to be operated on is fixed on a travelling table, actuated by a rack feed, which carries it through the saw. After each operation, by means of a quick return motion, the

table resumes its original position, preparatory to another cut. It is usual in these machines to run saws of a very thin gauge at a high speed, which obviates the unnecessary waste of valuable wood. The saw is fixed in a frame of light construction, working in a saddle or slide, which can be lowered or raised to suit the thickness of the boards to be cut. The saw, which requires little power to drive, can be sharpened and set to cut both ways of the traverse. The countershaft is, or should be, fixed on a slide, so that the connecting rod can always be placed in the best position for driving, &c.

Where space is an object, a single-bladed frame, driven vertically, is sometimes used in lieu of above; but this machine has several disadvantages, as compared with the horizontal method; the saw cuts only one-half of the traverse, it requires more power, the work is hardly so clean or so much in quantity, and the log is more difficult to fix. A high-speeded frame should be very strongly made, the standards being well supported, and the whole framing being especially strengthened, to overcome the excess of vibration.

CHAPTER VIII.

PLANING AND MOULDING MACHINES.

AFTER the timber has been converted by means of circular or straight saws from the forest tree into deals. or boards, the internal economy of a saw mill is, or should be, so arranged that they naturally pass on to the planing, moulding, and other machines, for rapid conversion into articles of daily commerce. Planing and moulding machines must, after saws, be considered the most important of wood-working machines; and as their action and manipulation are very similar, and are oftentimes combined in one machine, we purpose taking them together. Before proceeding to machines driven by steam, it may be of some interest to notice briefly a few of the different kinds of plane irons worked by hand, as it will enable us to judge better of the principles involved and the work required to be done by a planing machine. A plane may be briefly described as a tool used by those who work in wood to produce straight, flat, and even surfaces in that material. Its construction and action are, however, too well known to need description here. There are a considerable number of planes, which are known by different names, according to their size and the purposes to which they are applied. Those chiefly in use