An aid to diagnosis practised by striking the patient's body with the fingers, in such a way as to make it give out a note. The technique was introduced in 1761 by Leopold Auenbrugger (1722–1809) of Vienna, the son of an innkeeper, who derived the idea from the habit of his father tapping casks of wine to ascertain how much wine they contained. According to the degree of dullness or resonance of the note, an opinion can be formed as to the state of CONSOLIDATION of air-containing organs, the presence of abnormal cavities in organs, and the dimensions of solid and air-containing organs, which happen to lie next to one another.