Second. The international code signal of distress indicated by N C.
Third. The distance signal, consisting of a square flag, having either above or below it a ball or anything resembling a ball.
Fourth. A continuous sounding with any fog-signal apparatus.
At night—
First. A gun or other explosive signal fired at intervals of about a minute.
Second. Flames on the vessel (as from a burning tar barrel, oil barrel, and so forth).
Third. Rockets or shells throwing stars of any color or description, fired one at a time, at short intervals.
Fourth. A continuous sounding with any fog-signal apparatus.