Laennec discovered "mediate" auscultation in 1816 while examining a female
patient whose stoutness made "direct" auscultation-where the physician placed
his ear on the chest of the patient-impractical. Taking a piece of stiff paper,
Laennec rolled it into a tube and placed one end on the patient's chest and the
other against his ear. He had inadvertently invented the stethoscope.
This first edition of Laennec's De l'Auscultation Médiate [On
Mediate Auscultation] depicts his stethoscope after three years of
experimentation. A wooden tube about 30 centimeters long and about 6.75
millimeters in diameter, the instrument was constructed in two pieces that could
be unscrewed for easier portability. Readers could purchase the instrument
directly from publisher at first, but the simplicity of the design allowed it to
be replicated by any competent woodworker.