above the explosion evaporated, forming a hole which rapidly got bigger.
At about thirty seconds, the general appearance was similar to a goblet; the ball I estimated to be about a mile in diameter and about four miles above the ground, glowing with a dull red; a dark stem connected it with the ground, and spread out in a thin dust layer that extended to a radius of about six miles. When the red glow faded out a most remarkable effect made its appearance. The whole surface of the ball was covered with a purple luminescence, like that produced by the electrical excitation of air, and caused undoubtedly by the radioactivity of the material in the ball. This was visible for about five seconds; by this time the sunlight was becoming bright enough to obscure luminous effects.
At some time near the end of the luminescence (I am not sure whether it was before or after) a great cloud broke out of the top of the ball and rose very rapidly to a height of about eight miles, expanding
