Published in 1913, a best-seller in the 1930s and long out of print, Physics for Entertainment was translated from Russian into many languages and influenced science students around the world. Among them was Grigori Yakovlevich Perelman, the Russian mathematician (unrelated to the author), who solved the Poincare conjecture, and who was awarded and rejected the Fields Medal. Grigori's father, an electrical engineer, gave him Physics for Entertainment to encourage his son's interest in mathematics. In the foreword, the book's author describes the contents as "conundrums, brain-teasers, entertai...