for holding the logs are sometimes merely steel rods, having heads like pointed hammer-heads, one end of the rod being fastened by and on to the set-beam, the other end being driven into the log. Bin, those on head blocks and tail blocks are inure complicated, being arranged so that two of them bite into the upper and under surfaces of the log in opposition to one another, being forced in by screw or eccentric motion. For en abling the saw to work close up to the uprights, there are what are known as last-board dogs, which project- only about one-half inch from the uprights, and may be used after the other dogs have been retired by reason of the to having been nearly entirely sawed away.
A saw-mill dog, brought out by the Knight :Manufacturing Co., of Canton, O., belongs to that class in which an adjustable head carries the dog-bit, and is secured at any point on a horizontal sliding bar, with a lever connection to force it into the timber. The upright is formed of two parallel straight pieces, on one of which slides the head carrying the upper dog-bit, giving adjustability in height ; the locking mechanism for this being an eccentric and lever. The lower dog is inclined at an angle of about 45• with the vertical, its lower end being turned up to about the same angle. It is controlled by the lever which operates the upper dog. The lower dog-bit moves upward until it strikes the timber, then upward into it, both clogs being locked in position when first in the timber. To operate the upper dog, the dog bit is dropped on the log, and is forced downward into the timber by drawing downward upon the long lever. When released from its bite in the timber, thelower dog returns to its original position, automatically locking itself, and remains there out of the way until again liberated by the operator. These dogs are made right and left-handed. For a right-hand mill a right hand dog is used on the front head block, and a left-hand one on each rear block ; while on a left-hand mill a left-hand dog is used on the front head block and a right-hand on the rear.
For holding quartered logs on the carriage there are employed what are known as quarter log dogs, which have two sets of teeth, sliding up and Flown on the upright, and each set ar ranged so that their points come in a vertical line, inclined about 45° to the horizontal, so that they can conveniently grip between them the corner of a quarter log, included between one of the sawed faces and the bark.
For rolling heavy logs on to the saw-mill carriage, and for turning them when slabbing. it is almost necessary to have a canting machine of some sort or other. One of the most
simple, which may also be used for drawing logs into the mill, consists merely of a horizontal drum, on the axis of which there is a spur wheel, driven by a pinion on a shaft, receiving power by belt. This device, when used as a log turner, is fastened to the timbers overhead, and a chain attached to the drum is carried along over open sheaves to the middle of the car riage, as it stands when run back to take on the longest sticks. In turning, the sawyer or his assistant takes down from overhead the hook which is attached to the chain and attaches it to the log, and by throwing on the belt-power causes the chain to wind up on the drum, and thus turn the log as much or as little as desired. Logs may be rolled from the log deck by passing the chain entirely around them once or twice, and then working as before men tioned. When used as a jacker for hauling in logs, there is required a longer spool, heavier gears, and longer chain, and the machine may be placed either under the mill floor, or over head, as maybe most convenient. The gearing and frictions should be heavy enough to enable several logs at a time to be hauled into the second story of a mill building.
One very well made log-jacker has an endless chain engaging with a pitch wheel and a shaft which is driven by spur and pinion, the shaft bearing this latter being driven by V frictions from a belted shaft.
A log-nigger moves the log from the table to the carriage, by a nearly vertical beam, piv oted at its lower end beneath the mill floor, and given slight oscillation in the direction in which it is desired to move the log, by a friction device hauling on a chain. The upper end of the beam next the log is armed with teeth which engage the logs.
A gauge-roll for board-sawing machines consists of a vertical roll on a horizontal bracket, which slides along a horizontal graduated scale, so as to bring the vertical roll at any dis tance from the saw, the motion being effected and the position of the roll maintained by the screw mentioned, and a hand wheel. A scale shows the actual distance between the saw and the roll. A horizontal roll at the back of the device serves as a support for the lumber passing over the frame. The arm which bears the vertical roll is hinged so as to swing out of the way when slabbing. The special use of such a roll is in sawing boards of different thickness, such as is known as dimension stuff, and in making the last cuts through a cant, as it prevents the lumber springing away from the uprights, and increases the evenness of thickness of the lumber.