The Velocity of Sound Waves and the Temperature in the Stratosphere in Southern California*

In 1904, G. von dem Borne investigated a region where an explosion of dynamite had been heard. He found that there were two distinct zones of audibility, one surrounding the source and another, separated from the first by a "zone of silence," at a greater distance. Many subsequent investigations have shown that usually two or more zones of audibility result from explosions.