The Speed of Sound Pulses in Pipes

Abstract

Speed of sound pulses in short tubes placed near a spark source; measured by the photographic method. By a modification of this method, an instantaneous photograph was obtained of a sound pulse, part of which had come through a tube, while another part had come through free air. In this way the effect of short tubes of various sizes was determined when their near ends were from one to five centimeters from the spark. Two photographs are reproduced which show that in some cases the pulse may travel faster through a short tube than in free air, and faster through the smaller of two tubes than through the larger. The speed through a tube was found to depend chiefly on the intensity of the pulse as it entered the tube, and this was true even when the motion of the air as a body was prevented by a thin collodion membrane stretched across one end of the tube. The mean speed was less the longer the tube.