Cryptanalysis of the Enigma Bletchley Park to describe the network that used the same Enigma setting sheets. Initially these were recorded using coloured pencils and were given the names "red", "light blue" etc., and later the names of birds such as "kestrel". During World War II the settings for most networks lasted for 24 hours, although towards the end of the war, some were changed more frequently. The sheets had columns specifying, for each day of the month, the rotors to be used and their positions, the ring positions and the plugboard connections. For security, the dates were in reverse chronological order down the
The Glory That Was century. Two of de Camp's friends and colleagues, science fiction writers Robert A. Heinlein and Isaac Asimov, with whom he had worked on military research during World War II, were involved in the book in different ways. It features a laudatory introduction by Heinlein and is dedicated to Asimov, whom de Camp stated "helped to push this one over the hump." Asimov recorded some vivid impressions of the author's research for the book in his own introduction to de Camp's short story collection "The Continent Makers and Other Tales of the Viagens" (1953). Twenty-seventh century Earth is united by a