Marine log-glass

From Object Wiki

Marine log-glass
Manufacturer	(unknown)
Production years	(unknown)
Production location	(unknown)

Fourteen-second log-glass in a crude wooden mount. Used in conjunction with a hand-log to estimate a ship’s speed.

[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: 1953-404