ClipArt ETC
"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

Pendulum Seismograph

"inverted Vertical Pendulum Seismograph. Marvin System. A stiff vertical tube, pivoted at its bottom…

"Seismoscope. a, heavy mass supported by loop at point near center of gravity; b, point on which upper side of loop rests; c, long needle projecting from upper side of loop; d, conducting-wire; e, binding-post; f, long arm of lever pivoted at k; g, point where end of lever rests on end of needle; h, mercury-cup." -Whitney, 1911

Seismoscope

"Seismoscope. a, heavy mass supported by loop at point near center of gravity; b, point on which upper…