India, March 20 -- Before wristwatches and smartphones, time in Delhi moved to the rhythm of water clocks and the Sun.

Mentions of water clocks date back to the 17th century during Shah Jahan's rule. Later, in the 18th century, the famous Jantar Mantar was built to use the Sun's position to read time.

Sohail Hashmi, writer and heritage activist, explained how drums of water were used to track time. "A vessel filled with water was used to float a smaller perforated vessel placed in the Red Fort. When it sank completely - which it did so every three hours - it marked one-eighth of the day, known as a 'prahar.' At this moment, drums would be beaten to declare the time."

A century later, "water clocks" were replaced by the grand astronomic...