The history of water clocks and two hydrochronometers by the monk Embriaco in Rome

​​Time's up! The expression comes from the water clocks so popular in antiquity. Devices for measuring time, based on the properties of water and vessels, were much in vogue both in Ancient Rome and in the East. But in the Dark Ages the European art of building clepsydras fell into decline, and they became a great rarity.

Whereas Eastern water clocks relied on a metal bowl floating on the water and gradually filling through a small hole, Western hydrochronometers were built from several vessels, and the water flowing out of them either turned a hand or dial, or the time was indicated by the movement of a float: and the modern age bestowed a multitude of curious variations on the mechanism.

Today Rome has two water clocks, designed by the Dominican monk Giovanni Battista Embriaco and presented at the Paris Exposition of 1867. One stands in the Pigna district near the Pantheon, the other in the park of the Villa Borghese on the Pincian Hill. The Hydrochronometer of the Pincio is a tower with four dials and glass walls through which the mechanism can be seen. It was restored in 2007 and now runs as good as new.