The history of Charles Babbage's early computing projects, from the head of the team that built a Difference Engine for the Science Museum. Interesting and well-written, with tons of technical detail, copious quotations from Babbage's writings, and a nicely even-handed approach to the various participants in the project. Thoroughly recommended.
I thought it was a pity that Swade repeated the "first bug" myth, though, given that he'd spent much of the first part of the book debunking myths about Babbage and Ada...
ISBN 0316648477.