Throughout history man has invented several systems for measuring time, more and more reliable and effective.
One of these is certainly the clepsamia or hourglass sand, tool consists of two containers of approximately conical shape connected to each other.
Let’s see in detail how it works.
The sand flows regularly from the bulb top to bottom in a precise time.
After just flip the tool to begin another period. The duration of the cycle depends on the amount and quality of sand, the size of the neck and the shape of the bulbs. As an alternative to sand are also used powdered limestone (from egg shells or powdered marble).
Currently this tool only has an aesthetic value, since more accurate tools are available and convenient. In the past, however, before the completion of the pendulum clock, was the only reliable tool for measuring time at sea and it is assumed that its use in this sense may have begun in the twelfth century. We only have evidence from the fourteenth century, when the hourglass sand is reproduced in several works by Ambrogio Lorenzetti.
During the voyage of Ferdinand Magellan around the globe, on every ship in the fleet were used clepsamie 18, and one of the duties of the crew was to overturn the right time. The synchronization clepsamie was made at noon, identifiable by the fact that the Sun reaches its maximum height above the horizon.