when was the seismicgraph invented?

Question

I am making a timeline on seismology an i need to know when the seismic graph was invented.

Answer 1

The seismograph today is way different from what it was nearly 1900 years ago. If you define seismography in a very broad sense (anthing that tried to measure the earth's tremors), then you are looking at three different stages.

The very first attempt was made in China around 136 A.D.This early eastern seismoscope consisted of a copper vessel with eight dragon heads attached to it, positioned above eight frogs.
Each dragon head held a ball in its mouth, which, when dropped due to the strong shaking of an earthquake, would fall into the open mouth of the frog directly below it. By noting which frogs contained balls after a strong earthquake, it was possible to determine how the Earth had moved in response to the earthquake.

The second stage of development took place in Europe atthe end of the 19th century. Several European inventors had constructed different seismographs. Most were electromagnetic and operated by suspending a magnetic mass, or pendulum, within an electric coil. Because a magnet moving inside a coil creates a current within the coil, the movement of the ground during an earthquake can be converted into an electrical signal.
This signal could then be used to modify the projection of light onto photographic paper, or to move a needle across paper and trace out the wiggles of the Earth's shaking. The amplitude of the signals recorded by old seismometers was limited by the amount of movement possible between the mass, or pendulum, and the seismometer housing.

Third stage of development occurred in 20th century.Today's high-technology, digital seismographs record ground shaking over a large band of frequencies and seismic amplitudes. Today's seismometers are called broadband because they are able to sense ground motion over a wide range of frequencies, from thousands of seconds to less than a hundredth of a second. Today's seismometers operate by measuring the amount of electrical energy needed to keep the mass centered in the housing in the presence of strong ground shaking. Modern seismometers can record a wide range of seismic signals, both very small and very large.

Answer 2

The seismometer was first invented by Zhang Heng in China in 132AD. Later John Milne invented the horizontal pendulum seismograph at the Imperial College of Engineering in Japan in 1880. This marked the beginning of modern seismology

Answer 3

The instruments were horizontal pendulums, designed by Ernst von Rebeur-Paschwitz to measure slight changes in the direction of the vertical.

http://inventors.about.com/library/inventors/blseismograph8.htm