When a ship is at sea, the officer in charge of the deck is usually expected to keep a bright lookout. A following ship must always keep clear of a ship ahead. If the weather is foggy the steam whistle is periodically blown. But foggy or clear, good weather or bad, at sundown all lights are in their places and the lookout man takes his stand in the crows nest. The lights of a steamer at sea, electricity being now much used, are a white light on the foremast head, a green light on the starboard bow or bridge, and a red light on the port, all of which have clearly defined significations, and to the initiated speak a plain language, which is thus poetically put by some ancient nautical genius.
At sea, two steamships meeting:—
“When all three lights I see ahead,
I port my helm and show my red.”
Two steamships passing:—
“Green to green or red to red.
Perfect safety, go ahead.”
Two steamships crossing:—
“If to my starboard, red appear,
It is my duty to keep clear