b'P ROVING THE P RINCIPLEscene of the explosion were not evenrattled, and at the very small settlement[Midway] some 12 miles from thescene.they barely heard the noise.Another surprise was that none of thesmall token charges went off during theblast. Robinson concluded that the for-mula he had been using to determinesafe air-gap distances, while correct atsea level, was probably not correct for ahigher altitude. He concluded that itmight be safe to permit closer spacingof magazines at high altitudes with thesame degree of safety. He and the Navycommanding officer immediately askedfor more explosives to do more air-gaptests. 17And so it went. The Army and Navywent on to do more barrier-wall tests,some using slabs of 3/8th-inch steelplate as part of the wall. They did box-car tests, wanting to identify the blastcharacteristics of projectiles stored lon-gitudinally on a boxcar. Results helpedthem advise how far from depot build-ings a loaded boxcar should be parkedto be safe. Later they sent up illuminat-ing star shells and white phosphorusCombining gun proofing and civilian habitat results were unexpected. The blast projectiles to find out how well theysometimes presented special hazards. effect of the detonation was lower than would perform as a smoke screen. 18he predicted.Perhaps the most spectacular tests were-This is presumably because of our alti the ones that blew up igloo-type maga-tude (4,950 feet) and the consequent zines loaded with explosives. Onlower density of air over that at sea August 29, 1945, at 9:36 a.m. Mountainlevel where most of the blast effects Time, the Navy exploded 250,000have been noted. Incidentally, this is inpounds of TNT. After the atomic bombline with our observation obtained itself, this blast was said at the time towhen firing guns at the Proving be the next largest deliberate detonationGround. Not only were no windows ever set. Seismologists, geologists,broken, but the windows at the Provingmeteorologists, and ordnance depotGround approximately 6 miles from therepresentatives from all over the coun-1 4'