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The hourglass also known as a sandglass, sand timer or sand clock is only about seven hundred years old. The sand flows within an individually handcrafted mouth-blown glass chamber and is accurate to within 60 seconds per hour which is quite remarkable for a 14th century technology. No batteries or winding required.
The hourglass is similer to the water clock. Both depend on a medium flowing out through a hole. But the hourglass has its own technological personality. It's far simpler and cheaper than the mechanical clock or the earlier water clock. Resetting it after it runs down is very simply, just turn it over. The only downside, a short-term timepiece. Its accuracy isn't bad once you solve some problems. A problem in early hourglasses was to find a free-flowing material that doesn't absorb water on a humid day and clog up. You can't load just any old sand into it.
Hourglasses were originally used on ships as early as the 11th century as a way of measuring time and speed at sea. They were one of the first reusable, dependable and reasonably accurate methods of measuring time. In the 16th century, hourglasses were used in churches to measure sermon lengths and in factories to calculate time for manufacturing procedures. They were later used within the culinary industry to measure baking and cooking times. They ran neither long enough nor accurately enough to be of much use in marine navigation. They were a poor person's timepiece. The hourglass became a metaphor for the running-out-of-sands we all inevitably face. It became, and it remains, a universal symbol of death.
Today the glass chamber is made of sturdy glass with a reinforced center funnel. The sand is screened to remove particles too large and too small, then baked completely dry to eliminate any chance for condensation to form. The sand is measured into the glass in a controlled environment, baked a second time, and capped. They are made of wood and brass that are very decorative. The hourglass is an enduring and beautiful work of art that will provide a silent, accurate, and unobtrusive channel of time. Watching the thin strands of sand create much the same effect as watching the flames of a warm fire. An Hourglass will add a soothing, meditative focal point to any office, school, or home setting. This is an ideal gift for teachers, professionals, or yourself. Also many people collect them.
