Jean Billon-Haller's unusual interchangeable design uses an endless screw (constantly turning from the spring-barrel) as a spring-barrel lock. The cylinder can be stopped at any time during the tune by turning the screw anti-clockwise, or at the end of the tune with the stop/play lever, which blocks the barrel and prevents it turning. Once the movement is set to play, the spring can only be released again by turning the screw clockwise. Compare lots 480 and 481.
The seven cylinders play a programme of operatic, religious, popular and American airs.