. . "A Calculus of Angels"@en . . "PS3561.E79 C35 1999" . . . "813/.54 21" . . . "A Calculus of Angels is the second book in Gregory Keyes' The Age of Unreason series. It was initially published by Del Rey on March 30, 1999. A follow up to Newton's Cannon, the book is set in 1722 and continues the alternate history where Isaac Newton discovers that alchemy works, and a powerful science is built upon it."@en . . "ISBN 978-0-345-40607-1" . . "39695456" . . "406"^^ .