184 DASA 2019-2 They were in the fog trying to get into the entrance te an atoll—I've forgotten which one, it may have been Kwajelein but I don't think so. They had a native on the bridge and the native said to the skipper, "I think you've gone past the entrance."' The skipper turned to the navigator, who said, ''No."' They tried to get in and found they were up against the sand, They went on and came back again, and then the native told them just where the entrance was. They went in at that point ard he was right, The captain said to the native, ''How did you know? "' "I could tell by the sound of the waves," was the response of the native. You probably know that the winds provide waves that hit the atoll which then produce a backwash that flows out from the atoll. This activity makes a perfectly steady lap, lap, lap on the side of the ship. When you come to the break where the entrance is, there is a shift in the sound because the waves differ. The captain told me that this was so fascinating to him that the next day he flew over the atoll, and, by jingo, you could see these waves flowing out in circles and the break in the waves at the point of the entrance. Does this fit in with your experience? DONALDSON: Yes. FREMONT-SMITH: But I like your story better! [Laughter] always right here’ is the best thing I've ever heard. "It's DONALDSON: Let's have a look at a few illustrations. Figure 27 is the Oak Shot. Inthe detonation, of course, we have some blast, some fire and some rediation, The meteorologists always are exact in determining the way the fallout is going to go. Sometimes they are right. It will leave a trail across the lagoon or inthe sea, . which one may or inay not be able to find. A detonation on the islets will produce a variety of effects. It wiil knock some palm trees over (Figure 2%), break them off, and you can say, ''Yes, the blast pressure was such."' Here you can make a direct measurement of the amount of blast it takes to fella palmtree. It's an appreciable amount of energy. Palm trees are made to resist winds. of almost hurricane force. It takes a certain amount of thermal energy to burn the leaves (Figure 29), One can make some exact compilations here of the amount of thermal energy that was produced at x number of miles, You can make this measurement directly.