张衡候风地动仪原理复原方案初探

FIRST TRY ON RESTORATION PLAN FOR PRINCIPLES OF HOUFENG SEISMOGRAPH INVENTED BY ZHANG HENG

本文依据范晔《后汉书·张衡传》有关记载,明确提出张衡候风地动仪所具有的各项性能及原理复原的目标及方案。按本文提出的原理复原方案,地动仪能够接受地震波中的“首波”,并可以此来确定地震的大致方位,在首波较弱,不足以报警时,则利用它来抑制后续横波,使横波不干扰方位角的测定。

The following article is based upon the account in Fan Ye's Book of Later Han Dynasty: Biography of Zhang Heng. It clearly puts forward the restoration plan for various functions and principles of the Houfeng seismograph by Zhang Heng. The plan stresses that the Houfeng seismograph can receive the vertical component and the horizontal component of the first seismic wave, and thus can be used to tell the approximate direction of the seismic source. When the first seismic wave is not strong enough for an alarm to be given, it is used to surpress the secondary wave to prevent such secondary wave as the shear wave from interfering the determination of the azimuth. The paper deduces that Zhang Heng had spent several decades for observing, experiment and improvement during the course of inventing this device.