It may be useful here to give some definitions of the various forms of ice to be met with in these latitudes, although there is frequently some confusion in their use. An iceberg may be defined as a detached portion of a polar glacier carried out to sea. The ice of an iceberg formed from a glacier is of quite fresh water. Only about an eighth of its mass floats above the surface of sea water. A "growler" is a colloquial term applied to icebergs of small mass, which therefore only show a small portion above the surface. It is not infrequently a berg which has turned over, and is therefore showing what has been termed "black ice" or, more correctly, dark-blue ice. Pack ice is the floating ice which covers wide areas of the polar seas, broken into large pieces, which are driven ("packed") together by wind and current, so as to form a practically continuous sheet. Such ice is generally frozen from sea water, and not derived from glaciers. Field ice is a term usually applied to frozen sea water floating in much looser form than pack ice. An icefloe is the term generally applied to the same ice (i.e., field ice) in a smaller quantity. A floe berg is a stratified mass of floe ice (i.e., sea-water ice). ICE MESSAGES RECEIVED. The _Titanic_ followed the outward southern track until Sunday, April 14, in the usual way. At 11.40 p. m. on that day she struck an iceberg and at 2.20 a. m. on the next day she foundered. At 9 a. m. (_Titanic_ time) on that day a wireless message from the steamship _Caronia_ was received by Capt. Smith. It was as follows: * * * * * CAPTAIN, _Titanic_: West-bound steamers report bergs, growlers, and field ice in 42° N., from 49° to 51° W., April 12. Compliments. BARR. * * * * * It will be noticed that this message referred to bergs, growlers, and field ice sighted on April 12--at least 48 hours before the time of the collision. At the time this message was received the _Titanic's_ position was about latitude 43° 35´ N. and longitude 43° 50´ W. Capt. Smith acknowledged the receipt of this message. At 1.42 p. m., a wireless message from the steamship _Baltic_ was received by Capt. Smith. It was as follows: * * * * * CAPT. SMITH, _Titanic_: Have had moderate, variable winds and clear, fine weather since leaving. Greek steamer _Athenai_ reports passing icebergs and large quantities of field ice to-day in latitude 41° 51´ N., longitude 49° 52´ W. Last night we spoke German oiltank steamer _Deutschland_, Stettin to Philadelphia, not under control, short of coal, latitude 40° 42´ N., longitude 55° 11´ W. Wishes to be reported to New York and other steamers. Wish you and _Titanic_ all success. COMMANDER. * * * * * At the time this message was received the _Titanic_ position was about 42° 35´ N., 45° 50´ W. Capt. Smith acknowledged the receipt of this message also.