Seismograph

Seismograph

DETAILS/DESCRIPTION:

In 1880 the English geologist John Milne* developed the first seismograph while working in Japan. When there was an earth tremor, the movement caused a weighted horizontal pendulum to swing like a gate, moving a slitted plate so that a light beam, shining through it onto a mirror, moved. This moving beam caused a pattern to appear on light-sensitive paper, producing the familiar wavy line associated with earthquake records.

In 1906, in Russia, Boris Golitsyn* developed an electromagnetic version. Tremors caused a copper coil to move close to a magnet’s field and generating a varying electric current in the wire. This varying current moved down a wire to cause a mirror to wiggle. A light beam, shone at the mirror, reflected to pass through a slitted plate and produce the Milne effect on photosensitive paper.

ONELINER: The seismograph

OTHER CONNECTIONS: None

BIBLIOGRAPHY:

Encyclopedia Britannica

https://en.wikipedia.org/wiki/Seismometer

http://www.google.com/search?hl=en&lr=&q=Golitsyn+seismometer

http://www.ingenious.org.uk/site.asp?s=S2&DCID=1899-63