262 NICHOLLS'S SEAMANSHIP AND NAUTICAL KNOWLEDGE
. 38. What signals are made from a lightship or by the coastguards
on shore when a vessel is standing into danger?
39. Describe in detail step by step the procedure of getting communi-
cation by means of the'rocket apparatus. '
40. On what does the success of its operation depend?
41. What conditions must an approved line-throwing gun fulfil?
What precautions should be taken when getting into rocket line-throwing
communication with an oil tanker?
42. What is meant by an efficient bell?
43. What is an efficient steam whistle?
44. At what distance should the steam whistle be audible?
45. How are sound signals made in motorships?
46. How are side-lights screened, and what is the breadth of the wick
in an oil side-light?
47. What candle power should electric navigation lights be?
48. What type of electric lamps should be used and what is the
minimum size of filament?