between the surface and the floor of the Bikini lagoon--below an LSM around which were arrayed the remnants of the fleet from the first test. The magnitude of the explosion and its effects were stunning: a huge bubble thrust upward from the quiet lagoon and then burst into a tumult of spray; within seconds a tremendous column of water, hollow in the center, rose one mile into the air. The Arkansas, a 26,000 ton battleship was upended like a toy and then plunged to the bottom. The column, which was estimated to carry 10,000,000 tons (twenty billion pounds) of water, also carried with it sludge and sediment which the rising fireball had scooped from a circular half-mile area of the lagoon’s floor. Waves, 80 and 100 feet high, were sent out as the water fell back into the lagoon. The psychological trauma of the blast itself was so tremendous that some Operation Crossroads personnel, observing the event on ships more than 10 miles away, began vomiting over the side. If the effects of “Baker'" were stunning, then tnose of the "Mike" shot in the “Ivy" series of tests at Enewetok were astounding. ''Mike"’ was the name for the very first thermonuclear, or H-bomb, device ever exploded by man. It utilized liquid nydrogen cooled to almost absolute zero (-273.169 centigrade). It was a "device" and not a deliverable bomb, since the cooling apparatus involved weighed some 65 tons (62, p- 15). The cooling mechanisms and the fission and fusion material were located in a building on Elugelab Island of Enewetok Atoll. When "Mike" was detonated, not only did the island disappear, it was vaporized into calcium oxide and sucked up with the cloud, but the blast Te lO1bb 18.