The blue hourglass sand timers have been used through the centuries and still maintain a high symbolic value. They are aesthetically pleasing ornaments, just enough accent and color to any setting, rather than accurate timepieces.
Hourglass sand timer may be reused indefinitely by inverting the bulbs once the upper bulb is empty.
Hourglass sand timer is a mechanical device used to measure the passage of time. It comprises two glass bulbs connected vertically by a narrow neck that allows a regulated trickle of material (historically sand) from the upper bulb to the lower one. Factors affecting the time interval measured include the sand quantity, the sand coarseness, the bulb size, and the neck width.
- See more at:sand timer