Zhang Heng and the Incredible Earthquake Detector

Set in 132 CE, this story follows a Chinese scientist who creates a device that indicates the direction from which an earthquake began. Earthquakes have caused many deaths in China, and news can take days to reach Emperor Shun Di from a city. Against that problem of delayed communication, Zhang Heng develops his detector. The book focuses on earthquakes, an invention designed to locate their source, and the historical setting in which the device is made.