MECHANICS AND USEFUL ARTS. 41 



carriages and grope their way as best they could out of the tube. Such 

 a predicament certainly would not be enviable, but it might be more lu- 

 dicrous than dangerous. 



Ttie train used consisted of one very long, roomy, and comfortable car- 

 riage, resembling an elongated omnibus, and capable of accommodating 

 some 30 or 35 passengers. Passengers enter this carriage at either end, 

 and the entrances are closed with sliding glass doors. Fixed behind the 

 carriage there is a framework of the same form, and nearly the same di- 

 mensions, as the sectional area of the tunnel ; and attached to the outer 

 edge of this frame is a fringe of bristles forming a thick brush. As the car- 

 riage moves a'ong through the tunnel the brush comes into close contact 

 with the arched brickwork, so as to prevent the escape of the air. With 

 this elastic collar round it, the carriage forms a close titling piston, against 

 which the propul.>ive force is directed. The motive power is supplied in 

 this : At the departure station a large fin-wheel, with an iron disc, con- 

 cave in surface and 2.J feet in diameter, is made to revolve by the aid of 

 a small st itionary engine at such speed as may be required, the pressure 

 of the air increasing, of course, according to the rapidity of the revolutions, 

 and thus generating the force necessary to send the heavy carriage up a 

 steeper incline than is to be found upon any existing railway. The disc 

 gyrates in an iron case resembling that of a huge paddlewheel ; and from 

 its broad periphery the particles of air stream off in strong currents. 

 When driving the air into the upper end of the tunnel to propel the 

 down-train fresh quantities rush to the surface of the disc to supply the 

 partial vacuum thus created ; and on the other hand, when the disc is ex- 

 hausting the air in the tunnel with the view of drawing back the up-train, 

 the air rushes out like an artificial hurri ane from the escaped valves of 

 the disc case, making the adjacent trees shake like reeds and almost 

 blowing off his feet any incautious spectator who approaches too near it. 



When the down journey is to be performed the breaks are taken off the 

 wheels and the carriage moves by its own momentum into the mouth of 

 the tube, passing in its course over a deep air- well in the floor, covered 

 with an iron grating. Up this opening a gust of wind is sent by the disc, 

 when a valve, formed by a pair of iron doors, hung like lock-gates, im- 

 mediately closes firmly over the entrance of the tunnel, confining the in- 

 creasing atmospheric pressure between the valve and the rear of the car- 

 riage. The force being thus brought to bear upon the end of the train, 

 the latter, shut up within the tube, glides smoothly along towards its des- 

 tination, the revolving disc keeping up the motive power until it reaches 

 the steep incline, whence its own momentum again suffices to carry it the 

 rest of the distance. The return journey, as above indicated, is affected 

 by the aid of the exhausting process. At a given signal a valve is opened, 

 and the disc-wheel set to work in withdrawing the air from the tube. 

 Near the upper end of the tube there is a large aperture, or side- vault, 

 which forms the throat through which the air is, so to speak, exhaled, the 

 iron doors at the upper terminus still being kept shut. In a second or 

 two the train posted at the lower terminus, yielding to the exhausting 

 process going on in its front, and urged by the ord navy pressure of the 

 atmosphere from behind, moves off on its upward journey and rapidly 

 ascending the incline approaches the iron gates, which fly open to receive 

 it, and it emerges ut once into daylight. Such is the mode in which the 

 system works, and it seems capable of being adapted to railway commu- 



