in Exhausting Air from Tubes, S^c, 



5 



specific combination of apparatus to effect the before 

 expressed purpose, inasmuch as my improvements maybe 

 differently combined and applied, according to the rapidity 

 or rate of exhaustion required, and are applicable to any 

 kind of vacuum reservoirs, whether exhausted by air- 

 pumps by the withdrawing of water, or by the condensa- 

 tion of steam. 



The manner in which I prefer to carry such purpose 

 into effect is as follows : — 



I construct large vessels, or reservoirs, of suitable 

 materials. Such reservoirs or vessels may be of strong 

 boiler-plate ; but, for the sake of economy in construction, 

 I prefer building the reservoirs of brick, or masonry, in a 

 hemispherical shape, arched or vaulted, and supported 

 internally with suitable arches and pillars. I then cover 

 the external surface of such reservoir with thin sheets of 

 iron zinc, or lead, well rivetted and cemented or soldered 

 together, so that the masonry may render the structure 

 sufficiently strong, and the sheet metal may render it air 

 tight. Although the size and number of such reservoirs 

 may be considerably varied, I prefer having three reser- 

 voirs, each of the like internal cubic capacity as the 

 traction tube and connecting main, which such set of 

 reservoirs is intended to assist in exhausting; and, 

 although two such reservoirs will generally be found suf- 

 ficient, yet I consider it more advisable to have three, in 

 case of emergency, or unexpected leakage of the traction- 

 tube. 



I exhaust the before-described reservoirs by means of 

 such air-pump as is partly delineated in drawing sheet. 

 No. 11.5 in which many immaterial parts are omitted to be 

 drawn, for the sake of facility in delineation and descrip- 

 tion, and which pump I work by a steam-engine, con- 

 nected with it in manner shown in sheets, No. IV., and 

 No. V. 



A, A, represents the cylinder of the pump, which, as 

 regards the now describing apparatus must be of such 

 dimensions as to be capable of restoring the exhaustion of 

 the reservoirs in the interval between the running of the 

 trains on the section of railroad it is required to work. 

 And the steam engine, by which such pump is actuated, 

 is to be of such power as to work the pump, and restore 

 such exhaustion of the reservoirs with facility, in the 

 before-stated period, b, represents the piston, c, the 



