The split-seconds function is a type of complication that we find in wrist chronographs, which uses a delicate and very complex mechanism invented by Louis Frédéric Perrelet (1781–1852), so that intermediate times could be measured simultaneously to the use of the chronograph function.

Why was the split-seconds chronograph invented?

The split-seconds chronograph was born from the need to detect and record two events that have the same beginning but which do not stop at the same time. The aim of this function is therefore to be able to calculate two different time fractions having the same origin.

How does a split-seconds chronograph work?

The calculation of two different intermediate times is possible thanks to two superimposed chronograph hands . When starting the chronograph, these two hands move together and the secondary one remains hidden under the main one. Once you press a specific button, which is often found on the opposite side of the start and stop buttons or in the crown, the hidden sphere stops independently of the other.

We thus witness the split-seconds function that allows us to measure a split time without interrupting the stroke of the main chronograph hand. A further press of the same button (the rattrapante or split-seconds one) brings the second hand under the main one again, without altering the time measured by the latter.

Some of the most famous rattrapanti chronographs are the following:

Patek Philippe – Grand Complications

A. Lange & Sohne 1815 Rattrapante Annual Calendar

Richard Mille – McLaren F1

As you may have noticed in the captions, this complication is not so budget friendly… but it may be more practical and useful than minute repeaters… Click here to read about it!

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