not
restore the signal. The signal is set only in order that the train crew
may get into telephonic communication with the dispatcher, and in order
to do this, it is necessary for them to go into the booth in any case.

[Footnote A: We wish particularly to acknowledge the courtesy of the
Western Electric Company in their generous assistance in the preparation
of this chapter.]

REVIEW QUESTIONS

REVIEW QUESTIONS

ON THE SUBJECT OF TELEPHONY

PAGES 11--68

* * * * *

1. What are the advantages of a common-battery system?

2. When is the local battery to be preferred to the common-battery?

3. Enumerate the different kinds of line signals.

4. Make a diagram of the arrangement of a direct line lamp signal.

5. What is a direct line lamp with ballast? Give sketch.

6. Describe a line lamp with relay.

7. What is a pilot lamp and what are its functions?

8. Sketch three different kinds of batteries applied to cord circuits.

9. What is a supervisory signal?

10. Make diagram of a complete simple common-battery switchboard
circuit.

11. When will the supervisory signal become operative?

12. What is the candle-power of incandescent lamps used for line and
supervisory signals?

13. At what voltages do they operate?

14. What are visual signals?

15. Describe the mechanical signal of the Western Electric Company.

16. Give a short description of the general assembly of the parts of a
simple common-battery switchboard.

17. What is a transfer switchboard?

18. Outline the limitations of a simple switchboard.

19. Describe and sketch a plug-ended transfer line.

20. Why is the plug-seat switch not more widely adopted for use?

21. Make diagram of an order-wire arrangement.

22. What are the limitations of the transfer system?

23. What are the fundamental features of the multiple switchboard?

24. What is a multiple jack?

25. What is an answering jack?

26. Make a diagram showing the principle of multiple switchboards.

27. What is the busy signal?

28. What determines the size of a multiple switchboard?

29. What is the use of the intermediate distributing frame?

30. Make diagram of the series magneto multiple switchboard and describe
its operation.

31. What are the defects of this system?

32. Give a diagram of the branch terminal magneto multiple switchboard.

33. Give a diagram and a short description of the Monarch magneto
multiple