Before 1967, one second was defined by the rotation of the earth, and thus Neuchâtel observatory calibrated clocks via observations.

Now its telescope is used in a historical fashion by local amateur astronomers, while the calibration is done via atomic clocks.

The Bulletin de Marche stated the testing criteria, and the actual performance of the movement.

In 1936, irregularities in the Earth's rotation speed due to unpredictable movements of air and water masses were discovered through the use of quartz clocks.

All database entries are submissions to the wristwatch category ("chronometres-bracelet") at the observatory competition.