Souls in the Great Machine, by Sean McMullen, is the first book in the post-apocalyptic Greatwinter Trilogy. The book was published in June 1999. It is set in a future where electricity has been banned by all major religions, librarians fight duels to settle disputes and wind engines are the main form of mechanical power. The book deals with a machine called the Calculor, a great construction with many workers inside solving various equations, it is basically a human powered computer. The ambitious Highliber Zarvora Cyberline constructed the Calculor under the disguise that it will be used for calculation of taxes and other small tasks however Zarvora plans to use the Calculor for a much greater purpose of her own. (From: http://en.wikipedia.org/wiki/Souls_in_the_Great_Machine) It was originally published in Australia as two separate books, Voices In The Light (1994) and Mirrorsun Rising (1995).