The first seismograph (seen above) was invented in 132 A.D. by the Chinese astronomer and mathematician Chang Heng: “Each of the eight dragons had a bronze ball in its mouth. Whenever there was even a slight earth tremor, a mechanism inside the seismograph would open the mouth of one dragon. The bronze ball would fall into the open mouth of one of the toads, making enough noise to alert someone that an earthquake had just happened. Imperial watchman could tell which direction the earthquake came from by seeing which dragon’s mouth was empty.â€
(A 6.8 earthquake hit Mexico yesterday night. Fortunately all is well across the city, ’cause it sure shook long and strong.)