Accession No
0909
Brief Description
sand glass
Origin
Maker
Class
horology
Earliest Date
1700
Latest Date
1900
Inscription Date
Material
wood; ivory (?); glass; stone (sand)
Dimensions
height 169mm; diameter 77mm
Special Collection
Robert Whipple collection
Provenance
Inscription
Description Notes
Sand glass in wooden frame with four turned wooden pillars and circular ivory (?) feet at each end. Plug in one end of the glass. 2-minute glass.
Condition fair (one pillar broken); complete.
References
Events
Description
This is a two-minute glass, that is, turned over, with the upper glass full, it takes two minutes for all the sand to run into the lower glass.
Such simple methods of marking time were used when ‘streaming’ the ship’s log. The wooden log, attached to its rope, was thrown overboard; the frame was set with the upper glass full, and the rope was paid out as the ship sailed forwards. When the upper glass was empty, the sailor measured the length of rope paid out during that two minutes. From this, he could calculate the ship’s speed in nautical miles (knots) per hour.
04/08/2008
Created by: Dr Anita McConnell on 04/08/2008
FM:43566
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