A. Of copper and tin in the following proportions:—In every 5 pounds of bell-metal, there should be 1 lb. of tin, and 4 lbs. of copper.
Q. Why is this mixture of tin and copper used for bell-metal?
A. Because it is much harder and more elastic than either of the pure metals.
Q. Why is the sound of a bell stopped by touching the bell with our finger?
A. The weight of the finger stops the vibrations of the bell; and as soon as the bell ceases to vibrate, it ceases to make sound-waves in the air.
Q. Why does a split bell make a hoarse disagreeable sound?
A. The split of the bell causes a double vibration; and as the sound-waves clash and jar, they impede each other’s motion, and produce discordant sounds.
Q. Why does a fiddle-string give a musical sound?
A. The bow drawn across the string causes it to vibrate, and this vibration of the string sets in motion the sound-waves of the air, and produces musical notes.