Sand-glass

From Object Wiki

Sand-glass
Manufacturer	(unknown)
Production years	(unknown)
Production location	(unknown)

A sand-glass with cylindrical bulbs, graduated up to 19 minutes.

[edit] How it works

Although the action of a sand-glass has some resemblance to that of a water-clock, there is a fundamental difference in that the rate of passage of the sand is independent of the height of the column above the orifice. The angle of the double cone connecting the two chambers at the orifice is made equal to the angle of repose of the sand.

[edit] Memories

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

[edit] In the Science Museum's Records

Inv. No: 1911-209