Split-seconds chronograph watches
Split-seconds (rattrapante) chronographs have an additional seconds hand which measures intermediate times before immediately "catching up" with the other hand which has continued its movement. This intricate complication is also one of the most difficult to make, on a par with the tourbillon and the minute-repeater.
No sooner was the chronograph invented, in 1822, than watchmakers began searching for a way to simultaneously measure multiple events beginning at the same time (intermediate times, comparative times, reference times, etc.). The first watch to achieve this, devised by Winnerl in 1831, had a "monorattrapante" hand, that is a single, central seconds hand which could be stopped then made to instantly catch up elapsed time when released.
The two-handed system was introduced in 1838. Far more complex than a "simple" chronograph, a split-seconds chronograph features a clutch system with clamps that connect and disconnect the split-seconds hand and the main chronograph hand. Another distinguishing feature is their additional pushpiece. Pressing once on this pushpiece stops the split-seconds hand; pressing again allows the immobilised hand to catch up with the chronograph hand so that the two, superimposed, can continue together. This operation, which can be repeated any number of times, is especially practical at sporting events involving several competitors. Some chronographs have two or more "rattrapante" hands.