In watchmaking there are 3 grand complications. Holologists often speak of 3 classic high complications collectively known as “grandes complication”. They are the Perpetual Calendar, the Tourbillon, and the Minute Repeater.
A perpetual calendar is a mechanism that automatically takes into account the varying number of days in each month as well as leap years. Many also possess a moonphase function with indicates the waxing and waining of the moon. Most perpetual calendars are based on the Gregorian calendar so it will not need correction for more then a century. Other perpetual calendars can be secular perpetual calendars or jewish perpetual calendars. The perpetual calendar as inferred will display the day, date, month, and leap year cycle. Some perpetual calendar like the Audemar Piguet Millenary Perpetual Calendar also indicate calendar weeks. Obviously the perpetual calendar is a highly intricate mechanism that presents the watchmaker with a considerable challenge.
The tourbillon was invented by Abraham Luis Breguet around the turn of the 19th century. It was Breguet’s desire to greatly reduce the debilitating effects of gravity on watches. Pocketwatches being carries in coat pockets were subject to the negative effects of gravity. By mounting the delicate balance wheel and its related components in a delicate light weight carriage which rotated on its own axis, the negative effects of gravity ultimate cancel themselves out. Due to the delicacy of the construction and the emmence amout of care involved in the production of a tourbillion it remains a specialty of the most gifted watchmakers.
A minute repeater is a watch which tells the time audibly. It was development before the advent of electric power by Thomas Mudge. It has a mechanism via different sound sequences. It has a bass note for the hour, a treble-bass combination for the quarter hours and a treble note for the individual minutes. The result is a private symphony on demand on your wrist. Of the 3 grand complications described, the minute repeater is the most difficult to construct. Each minute repeater is like a snowflake, no two sound exactly alike. There are more complicated relatives of the minute repeater such as the Grande Sonnerie that add additional chiming sequences.
A chronograph is watch that is able to measure independent time intervals. It is a sense a stopwatch within a watch. Typically a chronograph has a mechanism that allows it to measure varying inverals of time. This is indicated on subdials of the watch dials. Typically a chronograph has 3 subdials. One is the subsecond dial which indicates that the watch is running. The more directly specifically important subdials indicate elapsed minutes and elapsed hours.
A flyback chronograph is a chronograph with a twist. Unlike typical chronographs which must be stopped before they can be reset to zero a flyback can be returned to zero while it is moving enabling one to time successive events without a undue lapse of time.
Split Second Chronograph
Split Second Chronograph is the most complicated chronograph. Instead of the ordinary single central stopwatch hand, two hands are superimposed over the other. When the chronograph is activated both hands will start in unison. However upon pressing the split-second button the lower hand will stop while the other hand continues forward enabling two events to be timed at once. By pushing the button again, the stopped hand will immediately catch up with the other hand and will continue to travel in unison. This complex mechanism places great demands on watchmakers as this type of chronograph undergoes much more violent mechanical stresses when used in its intended manner.
Retrograde displays have become popular with producers of high horology. Rather then a typical display in which a hand (such as a minute hand) completes a 360 degree revolution, a retrograde display completes 180 degree journey before flying back instantaneously to begin its travel once more. Anything from simple seconds to perpetual calendars can be displayed in a retrograde format.
A skeleton movement can be anything from a regular time watch to a minute repeater. The skeleton has had all excess metal removed from its structure of plates and bridges transforming it into an intricate artwork of beauty and delicacy.