the welte-mignon reproducing piano was a sophisticated cousin of the player piano, a mechanical instrument that could reproduce the subtleties of master pianists' styles by means of paper rolls. invented by edwin welte and his brother-in-law karl bockisch in freiburg, germany, in 1904, the system was applied to organs with the "welte philharmonic-organ" in 1912. the rolls, recorded between 1904 and 1932, are now historically significant as part of the welte-mignon legacy and as unique witnesses to the playing styles of the prominent musicians who played for the originals. these include mahler, debussy, faure, ravel, scriabin, and others, playing their own compositions, a historically invaluable resource. (they are particularly interesting when they make mistakes playing their own works.)