Wonderfully idiosyncratic and opinionated - as you would expect from L J K Setright. But, this is about as good a history of piston aero engines as you can find anywhere. Setright sticks to the main innovators - so most of the later part of the book is dedicated to US, British and German engines. But it covers all the major piston engines from the Gnome radials to the Napier Nomad. Setright's coverage of how the American radials came to dominate the world is also educative.