1911 Encyclopædia Britannica/Stethoscope

STETHOSCOPE (Gr. στῆθος, chest, and σκοπεῑν, to look, examine), a medical instrument used in auscultation (q.v.). The single stethoscope is a straight wooden or metal tube with a flattened bell, the surface of which is usually covered with ivory or bone at the end which is placed against the body of the patient, and a small cup at the other to fit the ear of the observer. In the " binaural " stethoscope, which has the advantage of flexibility, the tube is divided above the bell into two flexible tubes which lead to both ears.