The ground shook suddenly. Houses moved, and people ran into the streets with scare. With people running around, Zhang Heng stood still, thinking quickly. "There must be a way to know when this will happen," he thought. He had seen many earthquakes in his life, and each time, people couldn't do anything. But this time, Zhang Heng decided to find a method.
For days, he could think of nothing else but the earthquake. He was a man who loved science and understood the power of nature. After studying the stars, the sky, and the earth for years, Zhang Heng had an idea—what if there was a machine that could feel earthquakes before they happened?
Without wasting any time, Zhang Heng began to work on his invention. He used bronze (青铜) to create a large container with eight dragon heads, each holding a small ball in its mouth. At the bottom of each dragon, he placed a frog. If an earthquake happened, the shaking would cause the ball to fall into the frog's mouth, showing the direction of the earthquake.
Years of hard work passed. In AD 132, Zhang Heng completed the great bronze instrument, yet there was no immediate earthquake to confirm its accuracy. Not until AD 138—more than six years later—did the Seismoscope (地动仪) prove its worth.
On a calm morning, the dragon head pointing west released its ball while Luoyang felt no tremor. Court officials doubted the warning, but several days later, a messenger arrived reporting that Longxi, far to the west, had indeed been struck by a severe earthquake.
Though his name became famous, Zhang Heng never stopped searching for answers. He knew that science was a never-ending journey, and he was always ready for the next challenge.
a. The dragon head pointing west released its ball.
b. Zhang Heng completed the great bronze instrument.
c. Zhang Heng used bronze to create a large container.
d. Court officials doubted the warning.
e. A messenger arrived reporting the earthquake.
