Fifteen-second sand glass used in 1856 on Bark "G. W. Hall"
Collection
Instruments Collection
Made/Created
Date made
1856
Lexicon
Nomenclature 4.0
Nomenclature Secondary Object Term
Hourglass
Nomenclature Primary Object Term
Sandglass
Nomenclature Class
Timekeeping T&E
Nomenclature Category
Category 05: Tools & Equipment for Science & Technology
Material
Wood, Glass, Shell
Interpretative Labels
Label
Before the invention of accurate clocks, seafarers recorded the passage of time by means of the sandglass. These were typically mounted on a gimbal near the wheel or tiller. As the sand completed its passage from one glass orb to the other, this would be announced and recorded. Such records were essential for estimating distances travelled by the use of dead reckoning, before the invention of reliable chronometers. In fact sandglasses contain no sand, but rather tiny particles of shell. Sand tends to hold moisture and the irregular shape of individual sand grains tend to clog the narrow gap between the glass chambers of the sandglass. Shell fragments however proved to be more reliable.
