| Sand Timer |
| It is only with the introduction of the mechanical clock that time began to be measured in discrete units. It is a traditional way to measure time. It is the only time keeper of the earlier times that is least affected by temperature, humidity vibrations and swinging. An hourglass, also known as a sandglass, sand timer or sand clock, is a device for the measurement of time. It consists of two glass bulbs placed one above the other which are connected by a narrow tube. One of the bulbs is usually filled with fine sand which flows through the narrow tube into the bottom bulb at a given rate. Once all the sand has run to the bottom bulb, the device can be inverted in order to measure time again. The hourglass is named for the most frequently used sandglass, where the sands have a running time of one hour.
Factors affecting the amount of time that the hourglass measures include: the volume of sand, the size and angle of the bulbs, the width of the neck, and the type and quality of the sand. Alternatives to sand that have been used are powdered eggshell and powdered marble. |
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