21. Despite the simpler design, the seismometer was sensitive enough to detect Neil Armstrong's movements during sleep. 22. At tidal frequencies, gravitational acceleration was measured by monitoring the feedback current used to center the seismometer mass. 23. And it wasn't because Erich Lenz was changing the paper on the seismometer drums when the quake hit. 24. The depth of the earthquake prompted scientists in South America to install seismometer networks focused on long-period earthquakes. 25. Finally, a seismometer built by the University of Hawaii was lowered into position nearby and plugged into the junction box. 26. With inexpensive seismometer designs and internet access, amateurs and small institutions have even formed a " public seismograph network ." 27. A piece of paper is wrapped around a rotating drum of the helicorder which receives the seismic signal from a seismometer . 28. These impacts provided impulses that were recorded by the seismometer network to yield information about the geological structure of the Moon. 29. The event affected a number of health care facilities in Veterans Administration to install seismometer s at its high-risk sites. 30. I am guessing that it was a blast measurement device such as a seismometer , but don't know what kind.
