Pierre Charles Alexandre Louis played a valuable part in the development of the best in American clinical medicine of the 19th century.1 He accomplished this through his influence on an outstanding group of young American physicians who trained in Paris in the 1830's. One of these, Dr. James Jackson Jr., of Boston, in a letter to his father dated Paris, Dec. 1, 1831, writes2: "To practice percussion well is no easy thing, and no ordinary accomplishment. How often do men, or women pay five hundred dollars to learn to touch the piano; I would willingly give five hundred to any one who would teach me to percuss like Louis."
In 1843, Louis published his description of the zone of increased resonance which is sometimes found immediately above a pleural effusion and likened it to the "cracked-pot sound" (bruit de pot fêlé)3:
The cracked pot sound is not