SPECTEUM 243 much labor to the production of perfect gra- tings, and an engine (fig. 6) which he has re- cently made produces gratings more uniformly ruled than any known to us. On a hollow cast-iron block are cut, at right angles to each other, two V-shaped guides. On one of these guides slides the iron plate D, moved by means of a screw acting in a nut attached to its under surface. On this plate is fastened the plane of glass or speculum metal which is to be ruled. On the other guide slides the plate L J, having a reciprocating motion given to it by a lever, the action of which will be described further on. To this plate is attached the tool holder carrying the diamond-pointed cutter. The mo- tive power of the machine is a small turbine from which passes a cord around the driving wheel. On this driving wheel is a pin to which FIG. 6. Kutherfurd's Billing Engine. is jointed the connecting rod A F. This con- necting rod is hollow, and in it moves a rod which is constantly pressed toward the pin on the driving wheel by the spring shown at A. When the rod A F moves upward, the arm F I oscillates on its rocking shaft (the end of which is seen in the figure, projecting hori- zontally), until the end I of this arm comes against the fixed pin placed under it, and in contact with which it is shown in the drawing. Just before this upward movement of the rod A F begins, the pawl H falls into a notch on the wheel B, which is attached to the screw of the engine, and during the upward motion of the rod A F the pawl H presses against the notched wheel and rotates it a definite fraction of an entire revolution. The pawl H having completed its "throw," the crank pin on the driving wheel passes its upper centre, and then the slotted lever G lifts the pawl out of the teeth of the wheel B, so that no jarrings or tremors are given to the machine while the pawl is retreating to take a fresh hold on the feed wheel B. A pin attached to the connect- ing rod passes through a slot in the tube A F, and serves to hold the two together when the rod is making its downward motion. The amount of rotation to be given to the feed wheel B is regulated by rotating to the right or to the left the collar on the rock shaft, to which the pawl H is jointed. Directing atten- tion to the plate L J, to which is attached the cradle N carrying the diamond-pointed rod M, we observe at K the right-hand end of a rod the extremities of which pass through holes in the iron frame of the engine. This rod is moved parallel to the V guide of the plate L J by means of an oscillating lever which works in a vertical slot attached to the rod K, and is fixed on the same rock shaft which carries the lever F I. Projecting upward from the rod K is a short rod whose end is shown at L. This rod moves in a short slot cut in the direction of the length of the plate L J, as shown in the figure. The ac- tion of the cutting point of the tool M can now be explained. While the pawl H is rotating the feed wheel B, the rod L presses against the left-hand end of its slot and moves the slide J from right to left. The plate J can- not move, as above indicated, until the rod L touches the left-hand end of its slot ; and when it reaches this position the left-hand end of the rod K has moved to the left sufficiently to press against the lower point of the cradle N", and hold the diamond-pointed tool M elevated above the plate of glass or speculum metal during the entire left- hand motion of the plate J. When the end F of the lever F I descends, the rod K moves from left to right, and the projecting pin has to move up to the right-hand end of its slot before it can push the plate J to the right. During this motion of L in its slot, the left end of the rod K has allowed the diamond point on M to rest on the glass plate, so that before the plate J begins its right-hand mo- tion the diamond point is at rest on the plate to be ruled. The plate J now moves to the right, and the diamond point cuts a line. But the diamond point is lifted, before the right-hand motion of the plate J ceases, by the side arm O of the cradle N coming against the inclined surface of the side piece P. The diamond is thus raised, and is held in this position by the depression of O against P until the left-hand end of K has moved up to the cradle and holds the tool elevated du- ring the motion of the plate J to the left. After this motion has ceased, the diamond is lowered to the glass plate, and -another cut
