SfK WILLIAM SIEMENS, F.R.S. 333 



development cf railway traffic. Nothing could exceed the in- 

 genuity displayed in the contrivances exhibited ; but he observed 

 that the electric telegraph was left out of the interlocking arrange- 

 ments which had been brought forward. It was used only as an 

 auxiliary to signal trains from station to station, but it formed no 

 part of the interlocking system. In Germany and Belgium an 

 interlocking system had been adopted lately with most satisfactory 

 results, in which the three elements of the switch, the optical 

 signal, and the telegraphic signal were combined into an automatic 

 system ; so that it was impossible for a train to leave a station, for 

 the optical signal to be raised for its departure, and for the switch 

 to be put right, until the telegraphic signal had arrived from the 

 next station to say that the line was clear. He thought that no 

 interlocking block system could be looked upon as safe and com- 

 plete until it combined the three elements alluded to ; and he was 

 strongly of opinion that a block system, if adopted at all, should 

 be made absolute and complete, and not permissive, as had been 

 advocated in the course of the discussion. 



In the discussion of the Paper 



ON DEEP-SEA SOUNDING BY PIANOFORTE WIRE," 

 By SIR WILLIAM THOMSON, 



MR. C. W. SIEMENS * said : I may be allowed to make one or 

 two observations upon this interesting communication which Sir 

 William Thomson has made to us ; and I would say, like many 

 other mechanical arrangements which have been brought before 

 us, this is not absolutely new, and I am not surprised to hear that 

 attempts have been made to sound by wire instead of hemp line. 

 But the merit of the present apparatus, as well as of any other 

 well-devised mechanical arrangement, consists of the appliances 

 to make the result a perfect one, and in that respect I think 



* Excerpt Journal of the Society of Telegraph Engineers, Vol. III. 1874, pp. 

 225-226. 



