1884
THE NEW ZEALAND GAZETTE.
[No. 53

APPENDIX B.

ELEMENTARY QUESTIONS.

1. What parts of an engine are generally made of wrought iron?

2. What parts of an engine are generally made of cast iron?

3. For what parts of an engine is steel sometimes used?

4. What parts of an engine are generally made of brass or gun-metal?

5. Where is “white metal” sometimes used? On account of what property possessed by it is it adopted? What objection is there to its more general use?

6. For what parts is muntz-metal sometimes used? Is it malleable? For what properties is it valued?

7. What difference is there in the composition of cast iron, of wrought iron, and of steel?

8. How can cast iron, wrought iron, and steel be distinguished from each other?

9. What are the different properties of cast iron, of wrought iron, and of steel?

10. What is meant by the terms “breaking-stress,” “proof-stress,” “safe-working stress”?

11. What is the cohesive strength, or breaking-stress, of good ordinary wrought iron?

12. Tempering steel: how is it done, and in what order do the colours come?

13. What is case-hardening?

14. Which of the common metals or alloys can be forged, and which of them are brittle or “short”?

15. What is meant by “welding”? Which of the common metals can be welded?

16. The expansion of metals by heat: give examples of this in the engine and in the boiler.

17. In the construction of steel cylindrical marine boilers, for what parts have the plates to be worked hot? What precautionary treatment of these plates is afterwards necessary?

18. In what parts of cylindrical marine boilers is the strongest riveting employed? In which of the shell-seams is it most necessary?

19. What is “caulking,” and how are seams prepared for caulking?

20. Describe the different ways of fastening the ends of the main stays of a boiler. What are the merits of or objections to the different plans?

21. What stress per square inch is allowed on boiler-stays?

22. Describe a riveted stay, and state where such stays are commonly used.

23. Where are thin plates to be looked for in a boiler as it wears, and how is the thinness to be detected?

24. How are boiler-tubes fixed? What are “stay-tubes,” and how are they secured?

25. Where is it generally that boiler-tubes leak? How is this defect repaired? What are the causes of this leaking?

26. What are the causes of cracked tube-plates? Where are the cracks situated? How are they repaired?

27. What is the difference between a “dry uptake” and a “wet uptake”? Which requires most repair? Why? Where have you seen a wet uptake?

28. What is a superheater? What is its construction? What valves are on it? There is sometimes a gauge-glass on it: what is that for? Are superheaters in general use?

29. What parts of a marine multitubular boiler are first injured by shortness of water?

30. Where are angle-irons sometimes used in the construction of a boiler, and where are flanged plates used?

31. Priming: To what causes is it attributed? What means are applied to prevent it? What evils may be produced by it?

32. Funnel-draught: What makes it? What checks it?

33. Flame sometimes seen at the top of the funnel: What causes this appearance? Is it beneficial or is it detrimental? Why so?

34. A blast-pipe: What is its construction? Where is it placed? For what is it used?

35. How many bottom blow-off cocks are generally fitted to each boiler, and why are they so fitted?

36. Blow-off cocks are sometimes fitted with a spanner-guard: for what purpose is this? Describe how the guard is formed.

37. Water-gauge test-cocks: Where are they placed? At what heights? Must the cocks themselves be at those heights? What provision is made for cleaning these cocks should they ever become choked? When there are no test-cocks, how is the height of the water ascertained?

38. What is a dead-weight safety-valve? Of what are the rubbing-surfaces formed? How is a lock-up valve arranged to admit of lifting it or of turning it round, and to prevent adding to the weight?

39. About what area of safety-valve is now required by the Board of Trade? What is the effect of suddenly opening a safety-valve when steam is up? To about what extent do safety-valves rise when blowing off without being eased by hand?

40. Spring-loaded safety-valves: What advantages have they that are not possessed by dead-weight valves? What are the disadvantages, if any, as compared with dead-weight valves?

41. Of what pieces does a glass water-gauge mounting consist? How does it act? Where is it placed? At what height? Is it liable to derangement? How is its working tested?

42. Glass water-gauges have sometimes pipe-connections top and bottom: What is the object of this arrangement? Should there be cocks at the extremities of these pipes? Why, or why not?

43. Describe a Bourdon steam-gauge. Some gauges have an inverted siphon pipe below them: what is its use?

44. Why is a small cock sometimes put on the pipe leading to a steam-gauge? Where should it be placed, and what error might be made by omitting to use it?

45. Do steam-gauges indicate the total pressure of the steam, or only a portion of that pressure? What is the pressure measured from?

46. What is meant by the salting of the boiler? How is this prevented? What is the density of ordinary sea-water? How is the density ascertained? What is the difference between the formation of scale and the salting of the boiler? What is the maximum density at which boilers should be worked at sea? In the event of condenser-tubes leaking, what is the minimum density at which boilers should be worked? Give your reasons.

47. Scum cocks and pipes: How are they arranged? Where are they placed? At what height in the boiler? When are they used? When must