The purpose of this project is to construct a Stethoscope. The stethoscope is an acoustic medical device for auscultation, or listening, to internal sounds in a human or animal body. It is most often used to listen to heart sounds and breathing (breath sounds), though it is also used to listen to intestines and blood flow in arteries and veins. Less commonly, "mechanic's stethosopes" are used to listen to internal sounds made by machines, such as diagnosing a malfunctioning automobile engine by listening to the sounds of its internal parts. The stethoscope was invented in France in 1816 by René-Théophile-Hyacinthe Laennec. It consisted of a wooden tube and was monaural. His device was similar to the common ear trumpet; indeed, his invention was almost indistinguishable in structure and function from the trumpet, which was commonly called a "microphone." In 1851 Arthur Leared invented a binaural stethoscope, and in 1852 George Cammann perfected the design of the instrument for commercial production, which has become the standard ever since. Cammann also authored a major treatise on diagnosis by auscultation, which the refined binaural stethoscope made possible. By 1873, there were descriptions of a differential stethoscope that could connect to slightly different locations to create a slight stereo effect, though this did not become a standard tool in clinical practise. Rappaport and Sprague designed a new stethoscope in the 1940's which became the standard by which other stethoscopes are measured. The Rappaport-Sprague was later made by Hewlett-Packard, later Philips, and today there are still cardiologists who consider it to be the finest acoustic stethoscope. Several other minor refinements were made to stethoscopes until in the early 1960's Dr. Littmann, a Harvard Medical School professor, created a new stethoscope that was lighter than previous models. The stethoscope is used in aid of diagnosing certain diseases and conditions. The stethoscope is able to transmit certain sounds and exclude others. Before the stethoscope was invented, doctors placed their ear next to the patient's body in hopes of hearing something. Stethoscopes are often considered as a symbol of the doctor's profession, as doctors are often seen or depicted with a stethoscope hanging around their neck. Stethoscopes are also used by mechanics to isolate sounds of a particular moving engine part for diagnosis. Stethoscopes are sometimes used by safe-crackers to crack the combination to a safe.