They travel at a rate of rather more than a quarter of a mile in a second, or twelve miles and three-fourths in a minute.
722. Do all sounds travel at the same rate?
All sounds, whether strong or weak, high or low, musical or discordant, travel with the same velocity.
723. Why are bells and glasses stopped from ringing by touching them with the finger?
Because the contact of the finger stops the vibration of the atoms of the metal and glass, which therefore cease to impart vibrations to the air.
724. Why does a cracked bell give discordant sounds?
Because the connection between the atoms of the bell being broken, their vibrations are not uniform: some of the atoms vibrate more intensely than the others; the vibrations imparted to the air are therefore jarring and discordant.
725. Why, when we see a gun fired at a distance, do we see the flash and smoke, before we hear the report?
Because light, which enables us to see, travels at the velocity of 192,000 miles in a second; while sound, by which we hear, travels only at the rate of a quarter of a mile in a second.