Fig. 965. Oscillating engine. The cylinder has trunnions at the middle of its length working in fixed bearings, and the piston-rod is connected directly with the crank, and no guides are used.

Fig. 966. Inverted oscillating or pendulum engine. The cylinder has trunnions at its upper end, and swings like a pendulum. The crank-shaft is below, and the piston-rod connected directly with crank.

Fig. 967. Stamp. Vertical percussive falls derived from horizontal rotating shaft. The mutilated tooth-pinion acts upon the rack to raise the rod until its teeth leave the rack and allow the rod to fall.

Fig. 968. Another form of parallel ruler. The arms are jointed in the middle and connected with an intermediate bar, by which means the ends of the ruler, as well as the sides, are kept parallel.

Fig. 969. Traverse, or to-and-fro motion. The pin in the upper slot being stationary, and the one in the lower slot made to move in the direction of the horizontal dotted line, the lever will by its connection with the bar give to the latter a traversing motion in its guides a, a.

Fig. 970. Parallel motion in which the radius rod is connected with the lower end of a short vibrating rod, the upper end of which is connected with the beam, and to the centre of which the piston-rod is connected.

Fig. 971. A modification of the crank and slotted cross-head, Fig. 763. The cross-head contains an endless groove, in which the crank-wrist works, and which is formed to produce a uniform velocity of movement of the wrist or reciprocating rod.

Fig. 972. Section of disc-engine. Disc-piston, seen edgewise, has a motion substantially like a coin when it first falls after being spun in the air. The cylinder-heads are cones. The piston-rod is made with a ball to which the disc is attached, said ball working in concentric seats in cylinder-heads, and the left-hand end is attached to the crank-arm or fly-wheel on end of shaft at left. Steam is admitted alternately on either side of piston.

Fig. 973. Another arrangement of the Chinese windlass, illustrated by Fig. 798.

Fig. 974. The gyroscope, or rotascope, an instrument illustrating the tendency of rotating bodies to preserve their plane of rotation. The spindle of the metallic disc C is fitted to return easily in hearings in the ring A. If the disc is set in rapid rotary motion on its axis, and the pintle F at one side of the ring A pislaced on the bearing in the top of the pillar G, the disc and ring seem indifferent to gravity, and instead of dropping begin to revolve about the vertical axis.

Fig. 975. Bohnenberger's machine, illustrating the same tendency of rotating bodies. This consists of 3 rings, A, A', A-, placed one within the other, and connected by pivots at right angles to each other. The smallest ring A2 contains the bearings for the axis of a heavy ball B. The ball being set in rapid rotation, its axis will continue in the same direction, no matter how the position of the rings may be altered; and the ring A2 which supports it will resist a considerable pressure tending to displace it.

Fig. 970. What is called the gyroscope governor, for steam engines, introduced by Alban Anderson, in 1S58. A is a heavy wheel, the axle B, B1, of which is made in 2 pieces connected together by a universal joint. The wheel A is on one piece B, and a pinion I on the other piece B1. The piece B is connected at its middle by a hinge-joint with the revolving frame H, so that variations in the inclination of the wheel A will cause the outer end of the piece B to rise and fall. The frame H is driven by bevel-gearing from the engine, and by that means the pinion I is carried round the stationary toothed circle G, and the wheel A is thus made to receive a rapid rotary motion on its axis. When the frame H and wheel A are in motion, the tendency of the wheel A is to assume a vertical position, but this tendency is opposed by a spring L. The greater velocity of the governor, the stronger is the tendency above mentioned, and the more it overcomes the force of the spring, and the reverse. The piece B is connected with the valve-rods by rods C, D, and the spring L is connected with the said rods by levers N and rod P.

Fig. 977. Primitive drilling apparatus. Being once set in motion, it is kept going by hand, by alternately pressing down and relieving the transverse bar to which the bands are attached, causing the bands to wind upon the spindle alternately in opposite directions, while the heavy disc or fly-wheel gives a steady momentum to the drill-spindle in its rotary motion.

Fig. 978. Traverse of carriage, made variable by fusee, according to the variation in diameter where the band acts.

Fig. 979. Continuous rotary motion from oscillating. The beam being made to vibrate, the drum to which the cord is attached, working loose on fly-wheel shaft, gives motion to said shaft through the pawl and ratchet-wheel, the pawl being attached to drum and the ratchet-wheel fast on shaft.

Fig. 980. Another simple form of clutch for pulleys, consisting of a pin on the lower shaft and a pin on side of pulley. The pulley is moved lengthwise of the shaft by means of a lever or other means, to bring its pin into or out of contact with the pin on shaft.

Fig. 981. Alternating traverse of upper shaft and its drum, produced by pin on the end of the shaft working in oblique groove in the lower cylinder.

Fig. 982. See-saw, one of the simplest illustrations of a limited oscillating or alternate circular motion.

Fig. 983. Cylindrical rod arranged between 2 rollers, the axes of which are oblique to each other. The rotation of the rollers produces both a longitudinal and a rotary motion of the rod.

Fig. 984. Intermittent rotary motion from continuous rotary motion about an axis at right angles. Small wheel on left is driver; and the friction-rollers on its radial studs work against the faces of oblique grooves or projections across the face of the larger wheel, and impart motion thereto.