Heaven Cracks, Earth Shakes: The Tangshan Earthquake and the Death of Mao’s China by James Palmer Basic Books, 2012, 273 pages, US$26.99 It’s a sobering reminder of your own mortality when you pick up a book of history which deals with events at which you were present and even a participant. It’s particularly sobering when the author, no longer a young man, was born two years after the events he describes. Such were my thoughts when dipping into James Palmer’s Heaven Cracks, Earth Shakes, a book which describes the events of China’s cosmic year, 1976. Yes, I was there. I…