Signs of Icebergs.
How can a ship's commander know whether ice is near or not? On that point the United States Hydrographic Office gives the following information:
Before ice is seen from deck the ice blink will often indicate its presence. This is readily understood when it is known that it is caused by the reflection of the rays of light from the sun or moon.
On a clear day over the ice on the horizon the sky will be much paler or lighter in color and is easily distinguishable from that overhead, so that a sharp lookout should be kept and changes in the color of the sky noted.
On a clear day icebergs can be seen at a long distance, owing to their brightness, and at night to their effulgence. During foggy weather they can be seen through the fog by their apparent blackness, if such a term can be applied.
They can also be detected by the echo from the steam whistle or fog horn. This should be remembered, since by noting the time between the blast of a whistle and the reflected sound, the distance of the object in feet may be approximately found by multiplying by 550.
The presence of icebergs is often made known by the noise of their breaking up and falling to pieces. The cracking of the ice or the falling of pieces into the sea makes a noise like breakers or a distant discharge of guns, which may often be heard a short distance.
The absence of swell or wave motion in a fresh breeze is a sign that there is land or ice on the weather side.
The appearance of herds of seals or flocks of birds far from land is an indication of the proximity of ice.
The temperature of the air falls as ice is approached, especially on the leeward side; but generally only at an inconsiderable distance from it. The fall of the temperature of the sea water is sometimes a sign of the proximity of ice, although in regions where there is an intermixture of cold and warm currents going on, as at the junction of the Labrador Current and the Gulf Stream, the temperature of the sea has been known to rise as the ice is approached. If a berg be grounded, water flowing past it will be lowered in temperature and thus give an indication of its presence. Change of temperature may therefore serve as a warning, and frequent observations, both of the temperature of the air and the sea, should be taken and considered.
SIGNALS IN RELATION TO ICE.
Information as to wind, temperature, weather indications, and the state of the ice can be obtained by communicating with the marine signal stations of Newfoundland. St. Pierre, and Canada. These are situated at Cape Race, Cape Ray, Belle Isle, Chateau Bay, Amour Point, Galantry Head (St. Pierre), and St. Paul Island.
Wireless telegraph stations are operated for the Department of Marine and Fisheries of the Dominion of Canada by the Marconi Wireless Telegraph Company at most of these stations, and vessels fitted with Marconi apparatus can communicate with them.