Einstein's Clocks, Poincaré's Maps by Peter Galison

A very good book about Poincaré who anticipated relativity but wouldn't give up "ether." This book makes a very good case that far from languishing bored in a patent office, Einstein took to the job, applied himself and perhaps even was stimulated in his thinking of time by patents for methods of coordinating distant clocks. Time is the subject of this book and simultaneity is the entrance to relativity. Well done.