346 THE SCIENTIFIC rAl'KRS OF 



In the discussion of the Papers 



"ON THE PNEUMATIC TRANSMISSION OF TELE- 

 GRAMS," by RICHARD SPELMAN CULLEY, M. Inst. C.E., 

 and ROBERT SABIXE, Assoc. Inst-. C.E. ; and 



"ON EXPERIMENTS ON THE MOVEMENT OF Alll 

 IN PNEUMATIC TUBES," by M. CHARLES BONTEMPS, 



[Translated from the French by JAMES DREDGE.] 



DR. SIEMENS * said it was exactly four years since a paper on 

 the subject of pneumatic propulsion had been brought before the 

 Institution by Mr. Carl Siemens.t The object of that paper was 

 to describe a system of propulsions in tubes which had been 

 matured by his brothers and himself in the course of years, it 

 being a system of continuous flow, or a circuit system. This had 

 been established in Berlin in 18G4, in London in 1869-70, and in 

 a modified form in Paris in 1871-^. The scheme had been sub- 

 mitted to the Postmaster-General several years previous to its 

 application in London. The object was to despatch letters 

 throughout the metropolis by a system of circuits, uniting in one 

 or two common centres or pumping stations, whence parcels would 

 be sent out every five minutes to a number of receiving and 

 transmitting stations lying in a circle (similar in appearance to 

 that shown on the diagram representing the Paris system). The 

 current flowed round always in the same direction, conveying 

 with it a succession of carriers passing from any one station to any 

 of the others. The system differed materially from the former 

 method, by which one carrier was sent through a tube in one 

 direction, and went back by vacuum in the opposite direction. 

 Sir Rowland Hill looked favourably upon the scheme, and he was 

 indebted to Mr. E. A. Cowper, M. Inst. C.E., who was at that time 

 frequently consulted on engineering matters by the Post Office, 



* Excerpt Minutes of Proceedings of the Institution of Civil Engineers, Vol. 

 XLIII. Session 1875-76, pp. 135-140 and 156-160. 



t Vide Minutes of Proceedings of the Institution of Civil Engineers, Vol. 

 XXXIII. p. 1. 



