PRESIDENTIAL ADDRESS. 707 



relays through the wheels and axles, in consequence of which the relays, de-ener- 

 gised, break the circuit to the admission- valve, which closes, and allows the air 

 in the cylinder to escape, and the signal-arm, moved by gravity alone, assumes 

 the ' on ' or danger position. At the same time the short circuit is removed from 

 the section behind, directly the train leaves it, the relays are at once energised, the 

 admission- valve to the air-cylinder on the protecting post of the section is opened, 

 air enters, and the signal is pulled down to the ' off ' position. 



The speed at which traffic can be operated by this system of power signalling 

 is remarkable. At Earl's Court junction box forty trains an hour can be passed 

 ench way — that is eighty per hour — handled by the one signalman in the box. 

 As the train approaches the box both its approach to the section and its destination 

 must be notified to the signalman. When it is remembered that with ordinary 

 signalling, to take an express train for example, a signalman hears some twenty- 

 four beats on the gongs in his box, and sends signals to the front and rear box 

 which give altogether some twenty-four beats on the gongs in these two boxes, 

 forty-eight definite signals in all, for every express train he passes into the section 

 which his signals protect, it will be understood that the system must be profoundly 

 modified to admit such a speed of operation as eighty trains per hour per man. 

 The modification is radical. No gong signals are used at all. There is a small 

 cast-iron box standing opposite the signalman with fifteen small windows in it, 

 each about an inch and a half square. Normally each window frames a white 

 background. A click in the box announces the approach of a train, and a tablet. 

 appears in one of the empty windows showing by code the destination of the 

 train. The signalman presses a plug in the box, a click is heard, and a tablet 

 is seen in a precisely similar apparatus in the next box. When the train passes 

 the man presses another plug and the tablet disappears. 



Four wires run between the signal-boxes along the railway, and by combining 

 the currents along the four wires in various ways fifteen definite signals can be 

 obtained, a number sufficient for the District traffic. Each of the fifteen 

 combinations is arranged to operate one particular tablet in the box. Current from 

 these four wires is tapped off at intermediate stations and is used to work a train 

 indicator showing the passengers assembled on the platform the destinations of the 

 next three trains. The whole equipment is a triumph of ingenuity and engineering 

 skill, and is a splendid example of the way electricity may be used to improve the 

 railway service quite apart from its main use in connection with the actual driving 

 of the trains. 



The facts and problems I have brought before you will, I think, show the 

 important influence that scientific discovery has had upon our railway systems. 

 Scientific discovery and mechanical ingenuity have reduced the cost of locomotive 

 working to a point undreamt of by the pioneer locomotive builders. Electric 

 railways are the direct fruit of the discoveries of Faraday. The safety of the 

 travelling public was enormously increased by the invention of continuous brakes 

 and by the discovery of the electric telegraph, and is greatly increased by the 

 development of modern methods of signalling; and the comfort of travellers 

 is increased by modern methods of train-lighting, train-warming, and the train 

 kitchen. Inventions of a most ingenious character have from time to time been 

 made in order to furnish a steady and ample light in the carriages. The smooth- 

 ness of travelling on our main lines is evidence of the thought which has been 

 lavished both on the wheel arrangements of the carriages and on the permanent 

 way. Problenig^in connection with the continuous brake are many and interest- 

 ing. Some of the problems of modern signalling would have quite baffled the 

 scientific electrician a quarter of a century ago. When engineers endeavour to 

 apply the results of scientific discovery they often find themselves confronted by 

 new problems unperceived by the scientist. Together they may find a solution and 

 thus enlarge the boundaries of knowledge and at the same time confer a practical 

 advantage on the community. The pure scientist, the practical engineer, act and 

 react on one another both to the advantage of pure science and to the advantage 

 of the national welfare. The future success of our railways depends upon the 

 closer application of scientific principle both to the economic and engineering 

 problems involved in their working, some decrease in unprofitable competition 

 with one another, and a more just appreciation on the part of the State of the part 

 railway companies play in our national well-being. 



