13. What are ringing and listening keys?
14. Show symbols for ringing and listening keys.
15. State the parts of which a cord equipment consists.
16. Show step by step the various operations of a telephone system wherein the lines center in a magneto switchboard. Make all the necessary diagrams and give brief descriptions to show that you understand each operation.
17. On what principle does a drop with night-alarm contact operate?
18. What is the advantage of associating jacks and drops?
19. Describe the mechanical restoration as employed in the Miller drop and jack.
20. Describe the electrical restoration of drop shutters as manufactured by the Western Electric Company.
21. What complications arise in ringing of party lines and how are they overcome?