A great book, covering the history of typewriters and keyboards in generous (but not overpowering) detail, with loads of beautiful pictures.
For example, he talks (a lot) about the qwerty layout, and it's abundantly clear that it was not chosen to 'slow down touch typists' - as touch typing was only invented decades later. It does appear true that the layout coupled with the circular layout used internally in Sholes first machines did limit the clashing of neighbouring "type bars", but not by slowing down typers. There have been hundreds of alternative layouts, from Blickenderfer's Dhiatensor via Dvorak (who faked some of the infamous Navy Test") to Colemak, Workman and BEPO. But the top speed of people who really, really try to get fast is more-or-less the same. And for most of us, the limiting factor in writing is not the brain-to-keyboard phase, but rather the composition.