23. Show conventional symbols for magneto generators.
24. Sketch and describe the Western Electric polarized bell.
25. Give conventional ringer symbols.
26. What is the purpose of the hook switch?
27. Make sketch and give description of Kellogg's long lever hook switch.
28. Describe and sketch the Western Electric short lever hook switch.
29. Point out the principal difference between the desk stand hook switches of the Western Electric Company and of the Kellogg Switchboard and Supply Company.
30. Give conventional symbols of hook switches.