Ref. 3939H Production began in 1995 with the caliber RTO 27 PS, featuring 336 components and bearing the serial number 1903000. It is a technical exploit to incorporate, in a 12 1/2??? movement, a minute tourbillon carriage (made in steel, comprising 69 parts, weight 0,3 grams) together with a minute-repeating mechanism. The first watch of Ref. 3939H is illustrated in ?Patek Philippe Wristwatches?, by Martin Huber and Alan Banbery, 1998 Edition, p. 330. What is a Minute Repeater? A minute repeating watch tells the time both visually and audibly. A slide on the side of the case, usually near the #9, will activate two hammers in the movement. These hammers strike two gongs curled within the case. First one hammer strikes a gong of lower tonality; it will count out the hours. Then both hammers will strike both gongs alternatively to count out the quarter hours after that hour, and then the second hammer alone striking a gong of higher tonality will count out the minutes after that quarter hour. The repeating mechanism was developed by Daniel Quare. In 1687, he had patented a mechanism that sounded the hours and the quarter hours. The early repeaters used bells. At the end of the 18th century, two bent-wire gings became the more popular mechanism. In 1892, the first minute repeater wristwatch was produced by Omega, a model with a round-shaped case. What is a Tourbillon? A Tourbillon is a regulating mechanism in which the escapement of a movement is housed within a revolving carriage. It was developed in an effort to attain better precision. When a watch is in a vertical position, the force of gravity will speed the balance wheel as it moves in its downward (arc) direction and slow it as it moves upward, creating deviational errors of timekeeping. By placing the balance and escapement in a carriage that revolves 360° per minute, these errors become averaged and the timekeeping becomes constant and consequently adjustable. Created by Abraham Louis Breguet in 1795, the tourbillon is considered a difficult and complex achievement by any watch manufacturer.