In 1946, he published an account of the Trinity test as "Dawn Over Zero", which went through at least two revisions. He continued to work at the "Times" through the 1940s and into the 1950s, and published a book on defense against nuclear war in 1950. In 1951, his book "The Hell Bomb" warned about the use of a cobalt bomb – a form of hydrogen bomb (still an untested device at the time he wrote it) engineered to produce a maximum amount of nuclear fallout.