First hourglass
A 14th century hourglass
The first hourglass, or sand clock, is said to have been invented by a French monk called Liutprand in the 8th century AD. However, concrete evidence of this revolutionary new form of clock, which measures time by the descent of sand from one glass bulb to another, first appeared in European ship inventories from the 14th century. Arriving just in time for the “Age of Discovery”, the hourglass was ideal for ocean travel because the bobbing waves didn’t affect its accuracy.