The origin of the hourglass is unclear. Its predecessor the clepsydra, or water clock
There are no records of … See more

Little written evidence exists to explain why its external form is the shape that it is. The glass bulbs used, however, have changed in style and design over time. While the main designs have always been ampoule in shape, the … See more

While some early hourglasses actually did use silica sand as the granular material to measure time, many did not use sand at all. The material used in most bulbs was "powdered marble, tin/lead oxides, [or] pulverized, … See more

Hourglasses were an early dependable and accurate measure of time. The rate of flow of the sand is independent of the depth in the upper reservoir, and the instrument will not freeze in cold weather. From the 15th century on… See more

Unlike most other methods of measuring time, the hourglass concretely represents the present as being between the past and the future, and this has made it an enduring symbol of time as a concept.
The hourgl… See more

Because of its symmetry, graphic signs resembling an hourglass are seen in the art of cultures which never encountered such objects. Vertical pairs of triangles joined at the apex are common in Native American art; both in … See more

• Chemex Coffeemaker
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• Marine sandglass… See more