733. Why can we hear sounds at a greater distance on water than on land?
For various reasons: because the smooth surface of water is a good conductor; because there are fewer noises, or counter vibrations, to interfere with the transmission of sound; and because there are no elevated objects to impede the progress of the vibrations.
734. Why do sea-shells give a murmuring noise when held to the ear?
Because what may be called expended vibrations always exist in air where various sounds are occurring. These tremblings of the air are received upon the thin covering of the shell, and thus being collected into a focus, are transmitted to the ear.
735. Why can people in the arctic regions converse when more than a mile apart?
Because there the air, being cold and dense, is a very good conductor; and the smooth surface of the ice also favours the transmission of sound.
736. Why do savages lay their heads upon the earth to hear the sounds of wild beasts, &c.?
Because the earth is a good conductor of sound. For this reason, also, persons working under ground in mines can hear each other digging at considerable distances.
737. Why can church clocks be heard striking much more clearly at some times than at others?
Because the density of dry air improves the sound-conducting power of the atmosphere. The transmission of sounds is also assisted by the direction of the winds.