where heavy timber is sawn the friction of the wood, especially if green, causes considerable loss of power. This is somewhat lessened by the sawyer opening out the timber by means of wedges as it passes the saw. To obviate the chance of splitting the wood by this method, Mr. G. L. Molesworth, C.E., introduced in the year 1856 a self-acting revolving wedge, in the shape of a wheel, thick at its centre and sloping down to an edge at its circumference; it revolved on centres at the end of a lever, which was free to traverse along the feather of a rocking shaft. The rocking shaft had a lever, which caused the wedge to be held with an even pressure within the cut. The whole was arranged close behind the saw, and the wedge revolved by the friction of the wood as it advanced, and exerted an uniform pressure in relieving the saw, and could also adapt itself to irregular as well as straight sawing.

Fig. 4 represents a strong, well-designed rack bench by Messrs. C. Powis and Co., of London, especially adapted for the heaviest class of circular sawing. The timber is brought up and carried through the saw by means of a wrought-iron travelling bed, divided longitudinally by the saw, and made to travel over turned rollers by means of a strong self-acting rack gear. Other suitable rollers are fixed alongside the travelling bed, both behind and in front of saw, on to which the timber can be canted both before and after being sawn. The table can be arranged to travel at from 12 feet to 40 feet per minute, and after the cut is made the return motion is from 70 feet to 80 feet per minute. It is stopped or started by means of a treadle or lever under the immediate command of the sawyer. For breaking down heavy logs where few cuts are required,

where heavy timber is sawn the friction of the wood, especially if green, causes considerable loss of power. This is somewhat lessened by the sawyer opening out the timber by means of wedges as it passes the saw. To obviate the chance of splitting the wood by this method, Mr. G. L. Molesworth, C.E., introduced in the year 1856 a self-acting revolving wedge, in the shape of a wheel, thick at its centre and sloping down to an edge at its circumference; it revolved on centres at the end of a lever, which was free to traverse along the feather of a rocking shaft. The rocking shaft had a lever, which caused the wedge to be held with an even pressure within the cut. The whole was arranged close behind the saw, and the wedge revolved by the friction of the wood as it advanced, and exerted an uniform pressure in relieving the saw, and could also adapt itself to irregular as well as straight sawing.

Fig. 4 represents a strong, well-designed rack bench by Messrs. C. Powis and Co., of London, especially adapted for the heaviest class of circular sawing. The timber is brought up and carried through the saw by means of a wrought-iron travelling bed, divided longitudinally by the saw, and made to travel over turned rollers by means of a strong self-acting rack gear. Other suitable rollers are fixed alongside the travelling bed, both behind and in front of saw, on to which the timber can be canted both before and after being sawn. The table can be arranged to travel at from 12 feet to 40 feet per minute, and after the cut is made the return motion is from 70 feet to 80 feet per minute. It is stopped or started by means of a treadle or lever under the immediate command of the sawyer. For breaking down heavy logs where few cuts are required,