Allison's differential binaural stethoscope by Weiss and Son, London, c. 1858, English
French physician René Laennec (1781–1826) invented the monaural stethoscope in 1819. Initially he used a roll of paper when examining patients to conduct the sound made by the heart and lungs to his ear. Variations of his invention were developed in the following decades. The differential stethoscope was first described in 1859 by Scottish physician Dr Somerville Scott Allison (1813-1877). Each tube connected to its own chest piece and ear piece. This let physicians simultaneously hear two different sounds in different parts of the chest. They could also hear them one after the other. It was hoped the combination of sounds gave physicians a better basis for diagnosis. However, his instrument was found to be of not much use and therefore not widely used.