Word: bullen
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...made atomic explosions can help scientists explore the center of the earth, 4,000 miles down. This is the hope of Professor K. E. (for Keith Edward) Bullen of Australia's University of Sydney, who told a Toronto meeting of geophysicists last week that he has already used waves from A-and H-bomb explosions to refine his theories about the earth's deep metallic core...
Most information about the earth's interior, Mathematician Bullen pointed out, has been gained by recording and measuring the several kinds of waves sent out by earthquakes. As the waves travel through the earth, they are bent and reflected in complicated ways. Some waves move faster than others; some are absorbed entirely. By disentangling the jiggly lines made by instruments recording many earthquakes, seismologists have determined that the earth is formed of concentric layers of different materials, with iron-nickel at the center and stony oxides nearer the surface...
...Warning. Natural earthquakes, said Dr. Bullen, are not ideal as tools for earth study. Their waves often start from a large region, which makes them leave fuzzy records, like the shadows cast by a bonfire. Even worse, they give no warning, so seismologists have no time to start up the expensive, sensitive instruments they use when they want to record events of special interest...
...Professor Bullen and a group of colleagues tried to persuade the U.S., Britain and Russia to explode at least one smallish atom bomb for scientific purposes during the International Geophysical Year (1957-58). The effort got nowhere, partly because of public revulsion against all nuclear explosions, but in 1956 the British and Australian governments gave in advance the time and place of four military test shots in Australia's central desert. Seismologists in many countries were all set for the waves, and they gained new information from their highly detailed records...
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...