Proceedings of the Polytechnic Association. 921 



Paris, to Xantienes, distant about two miles. These were conducted 

 with varying success, and, of course, with rarying popularity, the 

 main difficulty in the way being the heavy expense of working, spite 

 of all promises of economy. 



The first successful apparatus is thus described : Unlike the late 

 methods where the cars pass through a tube, flie first pneumatic pro- 

 pulsion of vehicles was done by an apparatus which lay Ijetween the 

 rails, upon which the cars ran. At the top of this tube or pipe of 

 cast-iron, properly strengthened by circular flanges eccentric to the 

 tube, was a longitudinal gearing, the sides of which were planed taper- 

 ing upward ; a band of iron of the thickness of the tube was made 

 to fit the opening. Over this a band of leather was placed, extend- 

 ing some distance on each side of the iron band to which it was 

 firmly fastened. The part extending to one side was used as a hinge 

 for the valve. This was firmly pressed, tlu'oughout the whole length 

 of the line, against the tube, by means of a bar of iron. The part 

 extending on the other side rested on the tube in the place where it 

 had been planed smooth. Every time a train passed over the line, 

 the leather was impregnated with tallow and wax, and was pressed 

 by a roller against the tube, on which it adhered, closing the opening. 

 The closing became more perfect when a vacuum was made inside 

 the tube ; one of the results of the atmospheric pressure being to 

 force the leather against the opening. When the vacuum was formed 

 within the tube, the cars attached to the piston therein were drawn 

 with it toward the location of the power creating this vacuum. The 

 tube was closed at each end, where the engines and air-pumps were 

 situated, by valves of peculiar construction, which allowed the piston 

 to go in and out freely and smoothly without letting in the air. 

 !N^umerous other plans were conceived and experimented upon, all 

 however, being but modifications in some way of those of Clegg and 

 Samuda, the perfectoi's of the Medhurst invention. The atmospheric 

 railroads upon this plan do not seem to have had, by any means, a 

 healthy life of it ; the longest lived, we believe, was. that in Ireland, 

 which died about five years ago, being succeeded by the better under- 

 stood steam locomotion. 



The Pneumatic Dispatch in England. 

 The comparative success attained upon the roads above named was 

 sufficient, however, to create a lively public interest wherever an 

 inventor claimed to have discovered the remedy for the difficulties 



