The Discoverers by Daniel Boorstin

I re-read this recently, and - like the first time I read it - it was great. Essentially a history of science, but in classic Boorstin fashion, it's not a boring time-line of what happened when. He takes the time to go into detail about people and discoveries that he thinks are particularly interesting or important. And he asks (and answers) interesting questions - particularly the questions about why things didn't happen a different way.