CHAPTER V.

TIMBER AND DEAL FRAMES, ETC.

UNDER the above heading we purpose noticing the varied forms of machines generally known as reciprocating or mill saws. The straight or mill saw was known and in use some hundreds of years probably before the circular saw. The date of its introduction, and when it was first driven by other means than hand power, is uncertain; several writers, however, mention the fourteenth century as probably the earliest period. Montfaucon ('L'Antiquité Expliquée,' vol. iii., pl. 189) gives a representation of two ancient saws taken from Gruter, one the blade of a saw without any frame, and the other apparently a cross-cut saw. Some interesting accounts of an early saw frame or mill, as it is called, are given in Hardwicke's 'Miscellaneous State Papers,' from 1501 to 1726, p. 71. In the year 1555, the ambassador from Mary, Queen of England, to the Court of Rome, having noticed a saw mill in the neighbourhood of Lyons, describes it as follows: The saw mill is driven with an upright wheel; and the water that maketh it go is gathered whole into a narrow trough, which delivereth the same water to the wheel. This wheel hath a piece of timber put to the axle-tree end, like the handle of a broch, and fastened to the end of

a saw, which being turned by the force of the water, hoisteth up and down the saw, that it continually eateth in, and the handle of the same is kept in a rigall of wood from swerving. Also the timber lieth as it were upon a ladder, which is brought by little and little to the saw with another vice.' Before the introduction of saw frames driven by water or wind, timber was generally converted by the aid of the wedge and pit saw; the latter had a reciprocating motion given to it by two or more men. In isolated districts, or where little timber is required, these saw-pits are in considerable use even at the present time, and men can be found willing to convert some classes of timber at a cost not greatly in excess of that sawn by machinery; the process is, however, much slower, and as a rule not so well done. The earliest saw frames in use in this country were constructed almost entirely of wood, and are described by an old writer as follows: The common saw-mill, which is generally employed in cutting timber into planks, consists of a square wooden frame, in which a number of saws are stretched; this frame rises and falls in another wooden frame, secured to the foundation of the mill in the same manner as a window sash rises and falls. The timber to be cut is placed upon a horizontal bed or carriage, sliding upon the floor of the mill, which being sufficiently narrow to pass through the inside of the vertical or moving saw-frame, will carry the tree through and subject it to the action of the saw. The carriage is provided with a rack, which is engaged by the teeth of a pinion, and thus gives the means of advancing the carriage. The pinion is turned by means of a large ratchet-wheel, with a click moved by levers connected

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with the saw frame; when the saw frame rises the click slips over a certain number of teeth of the ratchet wheel, and when it descends to make the cut, the click turns the ratchet wheel round, and advances the wood forward just as much as the saw cuts during its descent. The trees are generally dragged up an inclined plane, through a door at one end of the mill, and being placed upon the carriage, they pass through, and are divided by the saw into two or more pieces, which are carried forward, and passed out at a door on the opposite side of the mill.'

Bentham, amongst other machines, supplied a number of saw frames to the Government establishments at the close of the last and the commencement of the present century. We do not find, however, record of any special invention made by him in relation to this particular class of machine. In 1805 and 1807 Brunel took out patents for improvements in sawing machinery, included in which was a method for fixing and tightening mill saws, which was introduced by him at the Royal Arsenal, Woolwich, and elsewhere. It may be described as follows:-Each saw has pieces of metal formed like hooks riveted on either end. The hook at the lower end of the saw falls into a proper recess made in the lower cross-bar of the frame, and the upper hook is engaged with the hook of a shackle or link which hangs upon the upper cross-bar, and has wedges through it, by means of which it can be drawn tight to strain the saw. As the tension of the saws is in a measure uncertain when the wedges of the shackles are merely driven by a hammer, Brunel employed a very ingenious steelyard, which exhibited the degree of tension given to the saw. A strong spindle ex

tended across the fixed uprights in which the saw frame slides, and above the top of these uprights, from one side of this spindle, a lever proceeds, which has a weight fixed at the end, and from the opposite side of the spindle two short levers are fixed. They were connected by links to a cross-bar, situated just over the upper cross-bar of the saw frame when it is at its greatest point of elevation. This cross-bar of the steelyard has a shackle upon it, which can be united by a key with any of the shackles upon the cross-bar of the saw frame, which shackles are, as before mentioned, united by the hooks with the upper end of their respective saws, and by this means the lever and its weight become a steelyard, to draw up any one of the saws with a determinate force. In using this apparatus, the crank is turned round to elevate the frame to the highest point. Two wedges are then put in between the saw frame and the uprights, and this holds the saw frame fast whilst the steelyard is applied. The sharpened saws are now put into the saw frame, by hocking them upon the lower cross-bar, and uniting the hooks to the shackles on the upper cross-bar. The link upon the cross-bar of the steelyard is united with the shackle of one of the saws, and by allowing the steelyard to descend it stretches the saw, the wedge being thrust in by hand as far as it will go, thus retaining the saw at the tension to which the steelyard has stretched it. This same operation is performed on all the saws, which are thus strained equally. Brunel also erected several reciprocating saws for the Government, including one working a specially thin-gauge saw with fine teeth, for cutting sheaves from lignum vitæ. The plan of holding and feeding the timber to be operated on is ingenious.

The tree of lignum vitæ is placed horizontally in a large vice, which is opened and shut by two screws, both moved at the same time by cog wheels, connecting them so as to move the jaws of the vice parallel. The machine being used for cutting the ends of the trees into proper thicknesses for the sheaves, the vice which held the tree was provided with a screw, which advanced and gave the proper distance every time a sheave was cut off. The vice was fitted on parallel slides, so that the pieces cut off should have parallel sides. This machine was used for cutting up the largest-sized trees, the smaller being converted by a circular saw fixed in a horizontal swinging frame, similar to the action of a gate or door. The timber was also made to revolve, thus presenting every part of its circumference to the action of the saw; the saw was therefore enabled to cut through a tree nearly its own diameter. The whole arrangement was decidedly clever, but our space precludes more than a passing notice. We must not, however, omit to add that Brunel was most ably seconded by the late Henry Maudslay, who carried out the inventor's ideas with the greatest skill and accuracy, and introduced many improvements of his own.

A patent was granted to Charles Hammond, London, 1811, for improvements in machinery for sawing and planing wood, described in which are feed rollers for bringing the timber up to frame and circular saws, &c. This same plan of feeding timber has been adapted to planing, moulding, and other machines, and has formed the subject of several patents, including that great American monopoly, the Woodworth planer.

We have before us the drawing of a deal frame for