Seventeenth-century portable sand-glass

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Portable sand-glass
Manufacturer	(unknown)
Production years	17th century
Production location	(unknown)

This probably dates from the seventeenth century and is of the earlier type in which two separate bulbs are joined together at the necks.

[edit] How it works

The timekeeping depends on the regular flow of sand through a small orifice. The time taken for one bulb of the sand glass to empty is a definite interval, at the end of which the glass can be turned over and the process repeated. Sand glasses are useful for measuring long periods of time, but prove inadequate for short time intervals.

[edit] Memories

Do you remember stories about sand glasses? Add your memories.

[edit] In the Science Museum's Records

Inv. No: 1937-186