XXIX
Moreover, the atmosphere is by constitution adapted to the transmission of sound.46 Of necessity this is so, since sound is nothing but an impact of the atmosphere. The clouds that [as indicated] are completely rent must therefore be hollow and taut. One sees how much more resonant empty vessels are than full, and distended ones than slack. So this accounts for the sound of tambourines and cymbals; the former resound because the blow upon the air is resisted at the farther side; the latter are beaten against the air directly, but unless there were a cavity in the instrument it would not tinkle.