Abstract: An apparatus and process for locating gas leaks in underground pipelines by detection of sound waves created by the leaking gas. The apparatus and process uses a sound transducer attached to an elongated probe inserted in the ground for a substantial portion of its length. The elongated probe and transducer combination has an effective mechanical resonant frequency equal to or below the electrical resonant frequency of the sound transducer. The passive sonic detection apparatus and process of this invention provides improved sensitivity for detection of sounds created by leaking gas and thereby more accurate pinpointing of the gas leak in an underground pipeline. In one embodiment acoustic reflection and absorption shielding is provided for reduction of system response to airborne noise.

Abstract: An apparatus is provided for counting crimp in fibers or filaments by moving a cell containing a specimen through a laser beam and detecting changes in radiation scattered by the crimped fiber. The radiation is observed by means of suitable electronic circuitry and a photodetector.