CATALOGUE OF THE MECHANICAL ENGINEERING COLLECTION. 21 



give the impulse in one direction, whilst the piston on the other end 

 of the beam, by means of the vacuum in the cylinder, gives the impulse 

 in the other direction. Cat. No. 180,616 U.S.N.M. 



Print from a Model Showing Two Rotary Motions in Opposite Directions 

 from the Same Engine. James Watt's Patent, 1784. Two Views. 



A crosshead is secured to the beam of the engine from the ends 

 of which two connecting rods convey the power to two separate 

 shafts by " Sun and Planet " devices. As the eight-hand shaft is 

 placed lower than the other, its connecting rod is jointed to a lower 

 part of the beam so that both may have an equal motion through- 

 out their entire revolution. This was probably intended for rolling 

 metals for coining. The gearing by spur wheel carries the power 

 to a mill for slitting. Cat. No. 180,620 U.S.N.M. 



Print of James Watt's " Crown Cam Motion," Patented, 1718. Adapted to 

 a " Hoisting Engine." Two Views. 



In this peculiar method a heavy crown cam is fixed on a vertical 

 axis. Beneath it is a rocking frame having two friction rollers 

 bearing on the inclined face of the cam on its opposite sides. The 

 rocking frame is moved up and down from the beam of the engine. 

 In all of the specifications of 1781 the engine was single-acting, and 

 to produce power on the up and down strokes of the piston the 

 connecting rod was heavily loaded. Cat. No. 180,618 U.S.N.M. 



Print of James Watt's '' Sun and Planet " Engine. Patented, 1781. 



In this invention the Planet is an internal geared wheel on the 

 connecting rod and is held in gear by means of a friction roller on 

 the lower end of the rod running around a fixed oval cam or guide 

 block. Cat. No. 180,619 U.S.N.M. 



Print of James Watt's " Ladder Motion," with Two Fixed Guide Pins or 

 Rollers. Patented, 1781. 



The ladder consists of a long rack on the lower end of the con- 

 necting rod, as much like a ladder as possible, working against the 

 teeth of a spur wheel fixed on the shaft. The bottom end of the 

 connecting rod carries a friction roller working in a large opening 

 in the guide plate, keeping the ladder always in gear with the spur 

 wheel on the shaft. The fixed guide pins keep the ladder in gear 

 the greater part o^ the up and down stroke whilst two projecting 

 pins from the ladder, one at the top, another at the bottom, keep it in 

 gear while passing the centers. Cat. No. 180,617 U.S.N.M. 



