Lincoln Ellsworth, a pioneer in arctic and antarctic exploration by air, and first to fly completely across both polar regions, died on 26 May 1951 following a heart attack. He was in his 72nd year. A restless desire to see new lands, cross new seas, and to expand earth's frontiers was the expressed motive in all that Ellsworth did. Born of wealthy parents, he decided early in life to devote himself to exploration, and gave up a life of leisure to fit himself to lead expeditions by aircraft, ship, canoe, submarine, dirigible, and on foot to Alaska, the Canadian Northwest, the Andes, and both polar regions. His expeditions were not mere stunts for fortune or self glory, but, in spite of the quiet way in which he organized them, they were often spectacular and in total added much to geographical science and to the record of courageous leadership. After brief periods at Yale, Columbia, and McGill universities, Ellsworth left college to become an axman on the first Canadian transcontinental railroad survey. Later he was a prospector and mining engineer in Alaska and the Canadian Subarctic. Going to France as a volunteer in the First World War, he qualified as a flier only to have his service curtailed by pulmonary illness. In 1924 he led a geological expedition across the Andes from the Pacific to the headwaters of the Amazon. In 1925, with Amundsen and Riiser-Larsen he attempted a North Pole flight from Spitsbergen, but was forced back after one of the two aircraft was lost. On the return Amundsen stated that Ellsworth with almost incredible hardihood and personal risk had saved the lives of the entire expedition. In 1927, with Amundsen and Nobile, Ellsworth flew across the North Pole in the dirigible Norge. In 1931, as representative of the American Geographical Society, he flew in the Graf Zeppelin on its arctic flight. For a time he supported Sir Hubert Wilkins' early attempts in the field of arctic submarine exploration. Although the submarine venture was unsuccessful, the association of these two explorers, when directed to the Antarctic, brought geographical results of the highest order. From 1933 to 1939, Ellsworth made numerous flights with Balchen, Hollick-Kenyon, and Lymburner in which he discovered nearly 400,000 square miles of the Antarctic Continent. His books include: 'The last wild buffalo hunt', 'Our polar flight', 'Search', and 'Beyond horizons'. He collaborated with Amundsen in 'The first crossing of the Polar Sea'. Although awarded high honours by his own and foreign governments and by scientific and exploring groups, Lincoln Ellsworth remained a sincerely modest man, quick to seek and act on the counsel of his expeditionary associates, whom he chose with care, but yielding to no one his unequalled leadership in courage and determination.