Word: seismographs
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...system is based on a type of seismograph in which a heavy weight is suspended so that it holds still while the earth waves move past it. The slight motion between the weight and electrical elements close to it creates a fluctuating electrical current. Before the current reaches the recording apparatus Pomeroy and Sutton pass it through a special galvanometer-a coil that makes a small weight move against the resistance of a delicate spring. The waves in which they are interested are long and of low frequency (40 to 50 sec.). They found that by choosing a galvanometer with...
Jumbles Made Sharp. The result was magical. Seismograph records that were hardly more than meaningless jumbles turned into clear, sharp records of distant earthquakes. When Dr. Sutton showed these records to a recent Washington meeting of seismologists, the contrast was so striking that the sophisticated audience burst into applause...
...began in the 1920s. Violence passed like a bad tornado. Scientists and statisticians grew to greater importance. Probably the most important geological breakthrough came when Geologist Everette Lee DeGolyer used a reflection seismograph on the Seminole plateau, sending man-made sounds deep into the earth and gauging the echo to find "the rock beds humped up into a little dome which might be a trap for oil." In 1930 the well blew in at 8,000 bbl. a day. "This was the most important well drilled in America since Spindletop; reflection seismograph revolutionized prospecting for oil as completely as Spindletop...
Tests on the Minute. Other knowledge has come from studying seismograph records of the U.S.'s great H-bomb tests in the Pacific in 1954. The U.S. Atomic Energy Commission gave the seismologists no help at all, but Dr. Bullen figured out the exact times of all four blasts. Apparently the AEC is a creature of habit: it exploded all its H-bombs at an exact multiple of five minutes after 6 p.m. Greenwich mean time. According to Bullen's figuring, Test Bravo (which killed the Japanese fisherman with radioactive fallout) exploded at 45 minutes, zero seconds past...
...marked the source of the earthquake, but also that it might turn into an erupting volcano and cause further shocks. The still-disturbed earth shook Mexico City with nearly 100 tremors during the week. Although many of them were so slight that they could be sensed only on a seismograph, the worst one was two-thirds as strong as last fortnight's big jolt, but caused little further damage...