Piccard, Auguste (ōgüstˈ pēkärˈ) [key], 1884–1962, Swiss physicist, b. Basel. He became a professor at the Univ. of Brussels in 1922. He and his twin brother Jean Felix (d. 1963) are known for their balloon ascents into the stratosphere; in Aug., 1932, Auguste ascended to 55,500 ft (16,916 m). He was a collaborator with Albert Einstein in developing instruments for measuring radioactivity. From 1946 he focused on the ocean depths, making several notable dives with his son, Jacques Piccard, 1922–2008, off the African and Italian coasts in a bathyscaphe of his own design. In 1960 Jacques Piccard, with U.S. Navy Lieutenant Donald Walsh, descended to 35,800 ft (10,912 m) in the Marianas Trench. Jacques's son Bertrand Piccard, 1958–, is also a balloonist; in Mar., 1999, he and Briton Brian Jones became the first to circle the earth nonstop, in the Breitling Orbiter 3. They wrote Around the World in 20 Days (1999). He and André Borschberg have alternated as pilots for the solar-powered Solar Impulse in long-distance, multistage flights across Europe and North Africa (2012) and the United States (2013).