Five monaural stethoscopes dating from between 1860 and 1890. These are made from ebony and fruitwood. French physician, Rene Theophile Hyacinthe Laennec invented the monaural stethoscope in 1816. This design, which is essentially a wooden cylinder with a hole bored out down the centre, was the earliest form of a diagnostic device for listening to internal sounds of the body (auscultation). The far right stethoscope is designed by Billings (also known as Billings type).