<P> In 132 , Zhang introduced an intricate seismoscope to the court , which he claimed could detect the precise cardinal direction of a distant earthquake . On one occasion his device indicated that an earthquake had occurred in the northwest . As there was no perceivable tremor felt in the capital his political enemies were briefly able to relish the failure of his device , until a messenger arrived shortly afterwards to report that an earthquake had occurred about 400 km ( 248 mi ) to 500 km ( 310 mi ) northwest of Luoyang in Gansu province . </P>
<P> In 132 , Zhang introduced an intricate seismoscope to the court , which he claimed could detect the precise cardinal direction of a distant earthquake . On one occasion his device indicated that an earthquake had occurred in the northwest . As there was no perceivable tremor felt in the capital his political enemies were briefly able to relish the failure of his device , until a messenger arrived shortly afterwards to report that an earthquake had occurred about 400 km ( 248 mi ) to 500 km ( 310 mi ) northwest of Luoyang in Gansu province . </P>
when was the seismograph invented in ancient china
when was the seismograph invented in ancient china
In 132
In 132