1882.] 



on Electric Railways. 



73 



line, so we arrange that the moving position of the earth fault, that is 

 the position of the train itself, is automatically recorded by the pointer 

 of a galvanometer moving behind a screen or map, in which is cut out 

 a slit representing by its shape and length the section of the line on 

 which the train is, as shown in Fig. 5. In addition, then, to the 

 small sections of 20 feet or more into which our auxiliary rubbed rail 

 is electrically divided, there would be certain long blocked sections 

 one mile or several miles in length, for each of which on the map a 

 separate galvanometer and j)ointer would be provided. [Experiments 

 were shown of the system of graphically automatically recording the 

 progress of a train.] 



Fig. 5, 



In the preceding systems there are several contact-boxes in each 

 section of the insulated rubbed rail, and several sections of the 

 insulated rail in each section of the line blocked, but in the next 

 system the rubbed rail is simply divided electrically into long sections 

 each of as great a length as the particular system employed to insulate 

 the rubbed rail will allow. In this case we arrange that the electric 

 connection between the main cable and the rubbed conductor shall be 

 automatically made by the train as it enters a section, and automatic- 

 ally broken as the train leaves a section. The model before you, 

 shown in the accompanying figure, is divided into four sections, each 

 about 11 feet in length, and you see from the current detectors that 

 as the train runs either way it puts current into the section just 

 entered, and takes off current from the section just left. 



[Exj)eriments were then shown of the ease with which an electric 

 train could be made to back instead of going forwards, by reversing 

 the connections between the revolving armatures and the fixed electro- 

 magnets of the motor ; also that the accidental reversal of the field 

 magnets of the main stationary generator, although it had the effect 

 of reversing the main current, j)roduced no change in the direction of 

 motion of an electric engine, the direction of motion being solely 

 under the control of the driver.] 



