Career
He is also the author of Prodigal genius. The life of Nikola Tesla (1944), published in 18 editions in German and English. and several other non-technical books on 20th century science. In 1953 he observed a feature on the Moon, on western shore of Mare Crisium, which he interpreted as a giant natural bridge, but it turned out to be an illusion.
Now this illusion is known as O'Neill's Bridge.
