or shores. This signal arrangement includes a small tank
on either side of the vessel, just below the water line. Within
each is a microphone with wires leading to the bridge. If
the vessel is near any other or approaching shore, the sounds;
conveyed through the water from the distant object are
heard through the receiver of the microphone. These arrangements
are called the ship's ears, and whether the sounds come
from one side of the vessel or the other, the officers can tell the
location of the shore or ship near by. If both ears record,
the object is ahead.


LIFEBOATS AND RAFTS

The construction of life-boats adapts them for very rough
weather. The chief essentials, of course, are ease in launching,
strength in withstanding rough water and bumping when
beached; also strength to withstand striking against wreckage
or a ship's side; carrying capacity and lightness. Those
carried on board ship are lighter than those used in life-saving
service on shore. Safety is provided by air-tight tanks which
insure buoyancy in case the boat is filled with water. They
have also self-righting power in case of being overturned; likewise
self-emptying power. Life-boats are usually of the whaleboat
type, with copper air-tight tanks along the side beneath
the thwarts, and in the ends.

Life-boats range from twenty-four to thirty feet in length
and carry from thirty to sixty persons. The rafts carry from
twenty to forty persons. The old-fashioned round bar