The Sandglass Still Works

Know how since the fifteenth century, sailors use to measure time? Yes, they can navigate by the sun or the stars, but the most reliable, accurate and indispensable instrument on the ship – hourglass, which is invented far before the wrist watch, like Naviforce NF9024 wrist watch. The sundial can show the time only in clear weather and only in the locality in which the ship is located, and the sand – a real salvation for sailors.

On any ship there is always at least three such measuring device: four hours – carry one device for measuring time, one minute and 30 seconds. By using the two last calculated speed of the vessel.

It is from here became traditionally to measure time "bottles" and "bottle bill" became quite popular. The device for measuring time, which is specially, followed the testimony of the hourglass, turn over half the unit and hit the ship's bell.

But hourglass appeared much earlier than the XV century. The principle of their action was known long before the beginning of our chronology. Since the time of Archimedes there are mentions of bottle clocks. Most likely, he was referring to sand.

Classic devices, like the wooden frame sandglass, for measuring time of this type are the two glass parts connected by a narrow neck of the glass vessel, anchored in a stable wooden stand. Depending on the measurement period in one of the vessels is filled with a certain amount of sand. In Western countries about such hours of talking in the beginning of XIV century, when in France have found a method of preparing superfine sand for them. It was finely sifted powder black marble, boiled in wine and dried in the sun. But the flask could be filled and crushed egg shells, and oxide of lead or tin.