336 EXPLANATION OF THE PLATES. 



eating by means of beveled wheels with the crank shaft. Four arms, 9, 10, 11, 

 and 12, are fixed to the rods v v and w w, for the purpose of moving the valves, 

 and a lever or handle (13), turning on a pin screwed on the pipe E, is used to open 

 and shut the steam valves when the engine is first set to work ; (see art. 566 ;) the 

 steam gauge (21) is for measuring the pressure of the steam above that of the 

 atmosphere, (art. 558.) and the condenser gauge (24) is for measuring the force of 

 the vapour in the condenser, (art. 559.) 



Fig. 3. 4. 5. and 6. represent the four-way cock as executed by Maudslay. 

 Fig. 5. is the plan taken at the horizontal line D E, in Fig. 3. and 4., which are 

 sections through the steam cock. In these figures E is the steam pipe, and F the 

 pipe leading to the condenser G. Fig. 4. is the steam cock or cone ground into its 

 seat, and provided with a grease cup H to afford a regular supply. 



Fig. 6. is a plan of the upper side of the steam cone. See art. 457 and 

 Plate xv. 



