NEVADA TEST SITE
Morgan, the 24th and final full-scale nuclear detonation of the summer 1957 Nevada test series was fired at 5 a.m. PST today. The experimental device, designed by the University of California Radiation Laboratory at Livermore, was suspended from a 67 foot diameter balloon at 500 feet above Yucca Flat.
The fireball had the hour-glass shape characteristic of some balloon detonations and as it climbed and cooled it was surrounded by an intense ionization glow. The mushroom cloud quickly separated from its stem and rose to 40,000 feet. It was being blown in an easterly direction. As had been the experience with most other balloon shots during the series, it was anticipated that there would be no more than traces of off-site fallout at any inhabited place as a result of this morning's detonation.
Design yield of the Morgan device was well below nominal.
The blast was heard at the control point as a sharp crack followed by prolonged rumblings. It was heard at Alamo as rumbles and bangs and as rumbles at Tonopah and Bishop (Calif.).