EXPLANATION OF THE PLATES. 



ACTION OF THE VALVES. 



The steam passing from the boiler A, by the steam pipe K, is regulated in its ad- 

 mission to the slide valves w, .r, by the throttle valve i, the rodjj, with its lever / 

 and adjusting arc j" being conveniently adapted for the same. 



The engine then, after being cleared of air, &c., through the blow valve I, is put 

 in motion by means of the starting lever p, and causes the eccentric 0, through its 

 rod o, to actuate the lever p, of the exhaustion balance-shaft X, a system of levers 

 q q, affording the means of engaging and disengaging the same, according to the ne- 

 cessity of reversing or stopping the wheels. And the shaft X, being connected with 

 the balance-shaft Y, of the steam slides by the levers u, u, and the rods u", it is clear 

 that both shafts will operate simultaneously on all four slide valves, which are con- 

 nected to the levers u, u', of the said shafts by the side links 9, 10, 11, 12. Now 

 when the lever p, is urged by o, from the condenser L, the steam slides w, x, will be 

 caused to descend, admitting the steam above the piston B', through the passage No. 

 1, while No. 2 will be closed by the slide x. The exhaustion slides y, z, ascending 

 at the same time, will permit the steam from beneath the piston to pass off, through 

 the passage No. 4 and pipe n, into the condenser, the passage 3 being closed by 

 the slide y. 



When the lever p, on the contrary, is drawn towards the condenser L, the exhaus- 

 tion slides will be depressed, while the steam slides are caused to ascend, thereby re- 

 versing the operation of the steam. 



The lever u, moreover, which gives motion to the steam slides is so contrived that, 

 the extremity of the rod " can be moved by an adjusting screw, through a consider- 

 able space in a slot seen at u, thereby lengthening and shortening the leverage, and 

 consequently the stroke of the steam slides. 



The steam is thus caused to act expansively, to such extent as the variable cir- 

 cumstances of the weather at sea may suggest, the advantages of which are shewn 

 in Arts. 422, 451, and elsewhere. 



Hall's condenser is shewn at L, of which 13 is the upper chamber, containing a 

 thin plate 14, completely perforated with small holes, by which the steam from the 

 cylinder B, is distributed in its passage through the pipes 15 15, to the bottom 

 chamber, 16. 



The pipes 15 15, are surrounded with cold water, which is supplied through the 

 pipe R', by the double acting pump R, R', whose motion is derived from the main 

 lever C, through the rods W T, and the lever U, which is supported by the bracket 

 V ; the waste water passing into the sea through the opening S. 



