Show vibration make sound anything stretched la Is likely to he be thrown into vibration or roade made to tremble by the force st ol 1 ilia air blowing it if it vibrates so dinst as to produce tile air way vava that our ear can hear then that la Is what we call sound this la Is what happens to the telegraph wires when they hum and osa if wo put our hand on tho the telegraph I 1 pole we eliell feel that hat tit alie a wires birc vibrato vibrate strongly styon gly enough to set the whole polo pole to io trembling too when tile tho air lit still stall you will not hear bear the tele telegraph Allies li humming vy |