in Kxhausting Air from Tuhes^ S$c. 9 



at dififerent times, as regards each other, and also as re- 

 gards the inlet- valves, which will he found to be effected 

 by the eccentrics, delineated in figs. 2 and 3, in sheet 

 No. III., the longer arc in which must be set so as to cor- 

 respond with the time during which its respective outlet- 

 valve must be kept closed, and the shorter segment with 

 the time such outlet-valve may be permitted to open. 



In order to make the power given out by the lastly- 

 described pump more fully available, I combine it with 

 one or more other pumps, so that during the exhaustion 

 of the traction-tube, pumps of a larger capacity may be 

 worked than the power of the steam-engine, or other 

 motive power employed, would suffice for : one of such 

 combinations is shown in sheets No. IV. and No. V., of 

 which sheets No. IV, is a partial elevation, and sheet 

 No. V. a ground plan, the letters and figures upon which 

 indicate similar parts, so far as the like parts are de- 

 lineated in each plan, a, represents an air-pump con- 

 structed as lastly hereinbefore described, and of such size 

 as to be worked with facility by the steam-engine, the 

 cylinder of which is shown at c. b, is another air-pump, 

 of similar construction to a. The pump, b, should be so 

 much larger than a, that a, and b, shall together be suf- 

 ficient to produce the required exhaustion of the traction - 

 tube according to the speed desired to be given to a train, 

 or the rate at which it is desired to exhaust the traction- 

 tube. D, D, represents the main shaft of the engine, of 

 which, D^, is a continuation capable of being put into 

 connexion with it by the clutch, e, and also of being dis- 

 connected whilst the engine is in motion, f, is the fly- 

 wheel. G, the crank working the pump, a. n, the crank 

 working the pump, b. i, and i^, are the pipes in con- 

 nexion with the inlet-valves of the pumps, k, a pipe 

 leading from the inlet-pipe, i, of the pump, a, to the under 

 part of the double way-cock, l, and communicating either 

 with pipe, M, or the pipe, p, as may be required. 



The double way-cocks, l, and s, are similar to the four 

 way-cocks, q, and r, which are represented in elevation 

 on the upper part of the sheet No. V, and are constructed 

 with hollow plugs, or stoppers, open at the bottom, and 

 having an aperture at one side of the plug, that a large 

 air way may be given with a moderate-sized cock ; the 

 upper parts of the cocks are rendered practically air tight 

 by stuffing-boxes ; a rod, adjustable by a screw, passes air 



