候风地动仪

hòu fēng dì dòng yí

the world's first seismograph invented by Zhang Heng 張衡|张衡[Zhang1 Heng2] in 132

候

hòu

to wait

风

fēng

wind

地

dì

earth

动

dòng

(of sth) to move

仪

yí

apparatus