Stethoscope
an instrument employed in auscultation. It was invented by Lænnec, who at first used a roll of blotting paper for the purpose of concentrating and conveying sound to the ear; but, according to Tyndall, the philosophy of the stethoscope was enunciated by Dr.
Robert Hooke (1635-1702). The common stethoscope consists of a hard rubber funnel to which two flexible rubber eartubes are attached. The funnel is applied to the chest, and the tubes to the ear of the physician who perceives the condition of the lungs by the sounds produced when the patient draws long breaths. The phoneidoscope is an improvement which conveys the most minute sounds to the ear.