The longest echo ever recorded in a man-made structure was set in an underground fuel depot constructed in Scotland before World War Two when a blank was fired from a pistol it lasted 112 Seconds.
The longest echo ever recorded in a man-made structure was…
The longest echo ever recorded in a man-made structure was set in an underground fuel depot constructed in Scotland before World War Two when a blank was fired from a pistol it lasted 112 Seconds.