On April 14, 1912, the Titanic sank as the result of a collision with an iceberg and a large number of her passengers and crew were drowned. As a direct result of this disaster an International Conference on the Safety of Life at Sea was convened in London. In order to protect transatlantic shipping from dangers of icebergs and field-ice it was clear that it would be necessary to institute a systematic patrol of the North Atlantic. This work was undertaken by the United States Coast Guard who have carried it out most ably under the direction of the International Ice Patrol Board. As at present organised, the patrol is carried out by three vessels. One is an oceanographic vessel fully equipped with a seagoing laboratory which attempts to make one current map per month of the area that appears most critical at the time. The other two are patrol vessels which make cruises of two weeks' duration and relieve one another every fifteen days.