The tourbillon system was made to compensate the Earth’s gravitational force by mounting the escapement in a revolving cage. It gives the watch a better accuracy. This complication is known as one of the most difficult to make.
Chronograph watches can measure and display elapsed time. Usually three subcounters on the dial display the elapsed seconds, minutes and hours.
Watches featuring a retrograde date have their hands moving across a scale which at the end of their cycle, return immediately to zero to start again.
The central second is the central hand of the dial which divides the minute into 60 units.