These seismometers used damped horizontal pendulums.
2.
The advantage of a horizontal pendulum is that it achieves very low frequencies of oscillation in a compact instrument.
3.
A mechanically coupled horizontal pendulum for measurements of the inclination of the Earth's surface was constructed here by Heinz Lettau in 1936 1937.
4.
He was elected a Fellow of the Royal Society in 1887 and persuaded the Society to fund 20 earthquake observatories around the world, equipped with his horizontal pendulum seismographs.
5.
It was the home and workplace of John Milne ( 1850 & ndash; 1913 ), inventor of the horizontal pendulum seismograph after he retired from the Imperial College of Engineering in Tokyo, Japan.
6.
Cracks formed in the rocks and a rock slide came within of the apparatus, and the foundation remained undamaged, but a small ( half-degree ) tilt of the unit was discovered that was apparently responsible for closing the horizontal pendulum contacts.
7.
When the paddle is pressed to the right, a horizontal pendulum is set into motion which rocks against the contact points, sending a series of short pulses ( " dits " ) at a speed which is controlled by the position of the pendulum weight.
8.
When the paddle is pressed from the left, a horizontal pendulum at the opposite end of the lever is set into motion, intermittently closing a set of contacts, sending a series of short pulses " ( dits ) " at a speed that is controlled by the position of the pendulum weight.
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