This ninth volume in The Adventure of Discovery & Inventions series covers the period 1900 to 1925. As the new century dawned, a second industrial revolution based on electricity and the automobile was gathering momentum. Henry Ford redesigned the factory to make the Model T widely affordable. Before long, plastics and stainless steel would also be part of the industrial mix. Powered flight stands out as a key invention of the early 20th century, but back in 1903 the Wright brothers' achievement went almost unreported. Subsequently, spurred on by the First World War, the aeroplane's development was rapid, and the war itself inspired other inventions, including the tank and sonar. Einstein turned physics on its head with his theory of relativity, while in America black musicians did the same for music and jazz was born. It would spread far and wide, helped by another iconic invention of the era - radio.