432 TUP: APPLICATIONS OF PHYSICAL FORCES. [BOOK IT. 



|)e seen in action in the Paris Exhibition of 1867, is much simpler, 

 at least for description. Fig. 303 gives an external view. The 

 method of working and the arrangements of the moving parts and 

 the distribution are as follows. 



On two parallel shafts, CO, are mounted two pieces in the form of 

 a portion of a crown, both edges being concentric with the corre- 

 sponding shaft and fixed by one of the extremities on a shoulder of 

 the latter. These pieces play the part of the piston in ordinary en- 

 gines. Their outside convex surfaces fit into an accurately bored 



FIG. 304. Rotatory engine : phases of a complete motion of rotation. 



cylinder, AA, and their inside concave surfaces move round two 

 sockets, cc, concentric with the shaft. The form of the different 

 pieces is calculated, so that each of the pistons in its motion may 

 work through a groove concentric to its own axis of rotation and 

 hollowed out of the fixed socket of the other piston. The result 

 of this arrangement is that the steam can never pass between one 

 of the pistons and the socket of the other. We will now see how 

 the steam works. 



It arrives by the supply pipe, B, from the boiler, and enters the 



