Pendulum Seismograph

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“inverted Vertical Pendulum Seismograph. Marvin System. A stiff vertical tube, pivoted at its bottom end, carries a very heavy mass near its upper end, and is rendered stable or astatic by the elastic reaction of a central steel rod which has its bottom end firmly fixed inside the heavy mass and its top end attached to the framework on the pier. The horizontal motion of the ground and pier relative to the steady mass is magnified 120 times and inscribed on smoked-paper record-sheets by two sets of multiplying levers. One records the north-south, the other the east-west component of motion.” -Whitney, 1911




William Dwight Whitney The Century Dictionary: An Encyclopedic Lexicon of the English Language (New York, NY: The Century Co., 1911)


TIFF (full resolution)

983×2400, 906.8 KiB

Large GIF

419×1024, 125.8 KiB

Medium GIF

262×640, 58.0 KiB

Small GIF

131×320, 16.1 KiB