wrought-iron tubular shaft, which is held in place by a box and lever, and balanced by a spring. An adjustable steel bearing supports the back of the saw, and it can also be used to hold down the work. An air pump for removing the sawdust is attached to the cross head.

Mr. James Kennan, engineer, of Dublin, has from time to time introduced improvements into fret-saw machines. In 1865 he brought out a simple machine. In a vibrating or oscillating frame a fret saw was strained; the frame derived its motion direct from a triple-action cam, having two or more actuating surfaces on the first motion-shaft, which was worked by the foot. On the inner and outer peripheries of this cam, which was a flange screwed to the side arms of the fly wheel, worked two pulleys covered with india-rubber, to prevent noise when running. These pulleys were carried at the lower end of a lever, the upper end of which was keyed to a rocking shaft, which vibrated in bearings fitted to the table of the machine. Two arms of a C form were also keyed on to the rocking shaft, and the saw blade strained between their two vibrating ends. By making two or more acting surfaces on the cam, any number of strokes of the saw can be secured. An india-rubber ball or bellows, inflated by the upward stroke of the saw, was attached for blowing away the sawdust from the line of cut.

Mr. W. J. Cunningham, of London, patented about 1865 a combined fret saw and drilling machine, of very simple construction. The drill was vertical, and worked by leverage, and could be attached with advantage to an ordinary lathe. We have recently seen a wellarranged machine especially adapted for dovetail work, designed by a Mr. McChesney. The saw is driven by

a cord passing over three sheaves, two of which are adjustable, and the tension of saw can be regulated thereby. The main frame is of C shape, and of light construction, but, to prevent oscillation, it is braced by means of a wire rope passed round its exterior. The table can be set to angle, to give the taper to the wood necessary in the curved form of dovetail it is designed to cut.

Messrs. J. A. Fay and Co., of Cincinnati, U.S.A., exhibited at the International Exhibition in Paris (1878) a very complete fret saw, which we illustrate herewith (fig. 26). As will be seen from the drawing, the body of the machine is cast in one piece. The reciprocating parts are made very light; the tension is flexible. The upper end of the saw is attached to a strap, which, at its upper end, is connected with a segment pulley and eccentric roller. To this eccentric roller is attached the straps, which are connected with two steel springs, made of a series of thin plates of different lengths. By this arrangement an almost equal tension throughout all parts of the stroke of the saw is secured. The eccentric roller is so adjusted that in the downward stroke of the saw the lessening flexibility of the steel springs is compensated for by the shortened leverage of the eccentric roller. The sliding cross-frame to which the springs are fitted is adjustable for different lengths of saws, and the small hand wheel in front of the machine sets the cross frame to any desired lead.' A patent combined brake and striking gear, worked by the foot, is attached, and is arranged to stop and start the saw gradually. The fast-and-loose pulleys are six inches in diameter, and are speeded to make 1,100 revolutions per minute.

Messrs. C. B. Rogers and Co., of Norwich, U.S.A., also exhibited a handy fret saw. The saw strainingframe consists of a light iron frame, adjustable to different lengths of saw, and has on either side a hardwood spring, with adjustable tension, and is connected by straps to the saw. The saw is held by a hook and pin at each end, which allows it to be easily detached. The back of the saw is fitted with and steadied by a guide.

We have seen another method of holding the fret saw introduced in machines made by J. Richards, of Philadelphia. In this machine the saw is not strained in the usual manner, but supported by steel antifriction guides fixed at its top to prevent it turning and give lateral and back support at the same time. The saws are fastened to a tubular slide running in bearings, and steel guides are fitted to the end of the sliding tube. A small fan-blower is attached for clearing away the sawdust. A very good plan for keeping the cutting line clear in lieu of a fan-blower is, to construct a small cylinder with a piston which can be arranged to blow a volume of air at each downward stroke of the saw, and will perform its work very effectually. For light ornamental sawing a simple and compact machine, worked by the foot, has recently been patented by a Mr. Barnes, an American. The reciprocating motion is given to the saw by attaching the saw arms to a continuously revolving wheel. This wheel is driven by straps attached to the treadle, and the ordinary crank is done away with.

If, in designing a band sawing machine, it was practicable to embody some of the various improvements we have noticed without infringing patent rights, the result should be a comparatively perfect tool, combining

that great desideratum in machinery the maximum amount of productive efficiency with the minimum amount of complication and loss from excessive wear and tear or breakage. As, however, this embodiment is unfortunately not practicable, we must content ourselves with a few general hints, which may be found of some service. The main framing should be rigid, and cast in one piece. For the lighter class of machines an ordinary flange casting is sufficient, but for the heavier type a hollow or box frame is to be preferred. Care should be taken that the frame is curved or bowed sufficiently to allow of ample room between it and the saw for the easy manipulation of the work. The saw wheels should be made as light as possible, and the upper wheel mounted in a slide, arranged to 'give' to the vibrations or any sudden impact of the saw. The saw-wheel spindles should be of steel, and run in double bearings of phosphor bronze. Sufficient care should be taken as to their lubrication. The periphery of the saw wheels should be covered with india-rubber or two thicknesses of leather, and turned inside and out, and accurately balanced. To lessen the breakage of the saws from expansion, contraction, or other causes, and to keep them at their proper tension, a weighted lever or spring should be fitted to the slide in which the top saw-wheel is mounted. Metallic friction guide-wheels should be provided to receive the back thrust of the saw, and adjustable wooden sideguides should also be added. On no account should the back of the saw be run against a fixed bearing.

In the heavier class of sawing it is found that, no matter how carefully it is operated, the saw is apt to buckle and run from the line; it is, therefore, neces