Bras d'Or Lake (brä dôr) [key], arm of the Atlantic Ocean, c.360 sq mi (930 sq km), indenting deeply into Cape Breton Island, N.S., SE Canada, and occupying much of the interior. A narrow channel links it with the sea. The region was the scene of important experiments in the early history of aviation. In 1907, Alexander Graham Bell founded at Baddeck the Aerial Experiment Association, and on Feb. 23, 1909, J. A. D. McCurdy piloted his airplane, the Silver Dart, a distance of half a mile.