Menlo Park, New Jersey. Thomas Alva Edison, with his colleague Clarke, is testing a dynamo 16 times more powerful than any previously made. The rotating armature alone weighs a ton and a half. It is attached to a 100-horsepower Porter Allen steam engine. Edison is convinced that the optimal speed is 350 rpm (revolutions per minute). The Porter Allen’s cast iron bed is 60 cm thick to dampen vibrations. But the base begins to shake underfoot. Edison, stopwatch in hand, continues to shout, “Up, up!” Clarke feels his hair stand on end. When they activate the speed indicator, it reads 750 rpm, dangerously close to the point of disintegration. Finally, they slow the engine down.
