A Calculus of Angels
| Author | Gregory Keyes |
|---|---|
| Cover artist | Therese Nielsen |
| Language | English |
| Series | The Age of Unreason |
| Genre | Alternate history, fantasy |
| Publisher | Del Rey |
Publication date | March 30, 1999 |
| Publication place | United States |
| Media type | Print (Paperback) |
| Pages | 406 |
| ISBN | 978-0-345-40607-1 |
| OCLC | 39695456 |
| 813/.54 21 | |
| LC Class | PS3561.E79 C35 1999 |
| Preceded by | Newton's Cannon |
| Followed by | Empire of Unreason |
A Calculus of Angels is an alternate history and fantasy novel by American writer Gregory Keyes, the second book in 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.