DESCRIPTION OF PLATES. xxv 



PLATE XXIII. 



Fig. 304. A centrifugal pump. The machine is first filled through the funnel A, 

 and when it is made to revolve, the water is discharged into a circular trough, of 

 which a section is seen at B and C. The valve at D remains shut while the pump is 

 filling. P. 253. 



Fig. 305. A pump consisting of two plungers, continued nearly to the height at 

 which the water is delivered. P. 254. 



Fig. 306. Lahire's double forcing pump. When the piston is depressed, the 

 water enters the barrel at the valve A, and goes out at B ; when it is elevated, it 

 enters at C and escapes at D. P. 254. 



Fig. 307. The common piston, coated with leather. P. 254. 



Fig. 308. Mr. Bramah's press. The pump A forces the water through the pipe 

 B into the barrel C, in which it acts very powerfully on the large piston D, and 

 raises the bottom of the press E. P. 254. 



Fig. 309. The common sucking pump. P. 254. 



Fig. 310. A bag pump, the bag or puff A being extended and contracted by the 

 motion of the piston. P. 255. 



Fig. 311. A lifting pump, the piston rod AB being drawn up by a frame. 

 P. 255. 



Fig. 312. A sucking pump, converted, by the addition of a collar of leathers at A, 

 into a forcing pump. P. 255. 



Fig. 313. A fire engine, on a construction similar to some machines described by 

 Ramelli. AB is the piston, working within a cylindrical barrel, and moved by the 

 handles C D. When the end C is depressed, the water enters through the valves E 

 and F, and is discharged at G and H ; when D is depressed, the water enters at I 

 and K, and is discharged at L and M, into the air vessel N, whence it is expelled by 

 the pipe O. The pipes P and Q, may be united, if it be required. P. 255. 



Fig. 314. From Ramelli. The wheel AB, revolving in the direction B A, carries 

 a portion of water C between itself and the sweep D E, which is intercepted by the 

 slider F, and forced up the pipe,E G. P. 256. 



Fig. 315. From Ramelli. The roller A, revolving within the reservoir B C, which 

 is nearly cylindrical, carries with it the slider D E, which is made to sweep the internal 

 surface of the cylinder from C to F, by means of a projecting surface acting on the 

 end D, so that the water G is forced through the pipe F. P. 256. 



Fig. 316. From the cabinet of Mr. Serviere. The wheels A and B carry, during 

 their revolution, a quantity of water from C to D, or from D to C, according to the 

 direction in which they are turned. P. 256. 



Fig. 317. Mr. Gwynn's patent water engine. The valve A is kept, partly by 

 means of the spring B, but still more by the pressure of the water, in contact with 

 the roller or piston C, which revolves within the box D E, and sweeps it from E to 

 F, so that the portion of water G is forced, during each half of a revolution, into the 

 pipe F ; or is drawn from F to E, when the roller revolves in a contrary direction. 

 P. 256. 



Fig. 318. A chain pump. P. 257. 



Fig. 319. The mechanism of Holl's acting pump. In the position of the stopcock 

 A B, here represented, the water flows out of the barrel C, and the piston D is 

 allowed to descend. The rod E then turns the stopcock, and the barrel C 

 communicates only with the pipe F, which fills it, and forces up the piston, until the 

 stopcock is turned back to its former position. P. 257. 



Fig. 320. The hydraulic air vessels of Schemnitz. The reservoir A being filled 

 with water, and B with air, and water being poured into the funnel C, the air in B 

 acts by the pipe D on the water in A, and forces it up the pipe E. P. 258. 



Fig. 321. A being the high water mark, and B the low water mark, the vessels C 

 and D are filled at high water from below, the air being suffered to escape by a 

 stopcock, which is opened by the fall of the ball F ; at low water the air will enter 

 the vessel D at B ; and before the next high water, the water C will be forced up the 

 pipe E. P. 258. 



Fig. 322. The fountain of Hero. Its operation resembles that of the hydraulic 

 air vessels, fig. 320 ; but the pipe D here ascends. P. 258. 



Fig. 323. The hydraulic ram of Montgolfier. When the water in the pipe A B has 

 acquired a sufficient velocity, it raises the valve B, which stops its passage, so that a 

 part of it is forced through the valve C, into the air vessel D, whence it rises through 

 the pipe E. P. 259. 



