Each essay in Group Theory in the Bedroom is followed by a section of “afterthoughts,” where I bring matters up to date, pass along comments from readers, and correct mistakes. This page of the web site is meant to serve the same purpose for the book itself. (The title might properly be Afterafterthoughts.)
From time to time I’ll post updates here, including feedback from readers. Please send all comments, questions, and corrections to Brian Hayes, brian@bit-player.org.
Schwilgue’s adding machine
The hero of “Clock of Ages,” the first of the essays in Group Theory in the Bedroom, is Jean Baptiste-Sosimé Schwilgué, who rebuilt the clock of the Strasbourg cathedral 150 years ago. He is introduced via the following anecdote:
Early in the nineteenth century, the story goes, a beadle was giving a tour of the cathedral, and mentioned that the clock had been stopped for twenty years and no one knew how to fix it. A small voice piped up: “Iwill make it go!” The boy who made this declaration was Jean Baptiste-Sosimé Schwilgué, who made good on his promise forty years later.
The story of Schwilgué’s renovation of the cathedral clock is all I had known of his life, but a few weeks ago—too late to revise the chapter—another aspect of his career came to light. It turns out he also built an adding machine, the earliest model known to be driven by typewriter-like keys similar to those of a modern calculator. Schwilgué and his son Charles patented the device in 1844. The patent apparently went unnoticed until 2003, when it was discovered by Denis Roegel of the University of Nancy. Roegel describes the machine in “An early (1844) key-driven adding machine,” IEEE Annals of the History of Computing, Vol.30, No. 1, January–March 2008, pages 59–65.