356 THE SCIENTIFIC PAPERS OF 



through Southwark : both would be equally near, and the inter- 

 mediate stations upon the two branches would be a considerable 

 distance from each other, and be thus accommodated by pneumatic 

 communication without increasing the time of transit between the 

 principal stations, and without involving an extra consumption of 

 air or power. On the Avhole, he thought that the radial system 

 was well adapted for very short distances, and for very light 

 carriers. If the object was to collect telegraphic messages from 

 the streets immediately adjoining St. Martin's-le-Graud, it would 

 be absurd to speak of establishing a circuit system, and Messrs. 

 Clark and Varley had established that communication in a very 

 efficient way. But whenever it was desired to carry pneumatic 

 communication beyond those limits, to extend it over considerable 

 spaces, so that not only a few offices in the City, but the whole 

 of the metropolis might derive benefit from it, it would be 

 absolutely necessary to resort to some such system as he had 

 advocated. 



In the discussion of the Paper 



"ON THE VENTILATION AND WORKING OF 

 RAILWAY TUNNELS," 



By GABRIEL JAMES MORRISON, M. Inst. C.E., 



DR. SIEMENS * remarked that the plan proposed by Mr. Barlow 

 was ingenious ; but it would be purchased at the cost of two lines 

 of valve, which would be a serious consideration, though not pre- 

 senting an insuperable difficulty. Another plan had some years 

 ago occupied his attention. When the Metropolitan line was in 

 course of construction he was consulted, through Mr. Fowler, Past- 

 President,- as to some means of preventing the emission of the 

 products of combustion, and he then proposed a plan by which an 

 ordinary locomotive might run through the tunnel without being 



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

 XLIV. Session 1875-76, pp. 67-68. 



