Ship’s 14-Second Sand glass, late 19th or early 20th Century

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This sand glass consists of a four-legged wooden frame, a circular top and bottom and two connected glass bulbs containing black sand. One leg is newer and attached with a nail instead of a wooden peg like the others, indicating a repair.
Sailors used this type of sand glass to measure the speed of a vessel; longer-timed examples were used to time duty watches. To measure speed, a triangular piece of wood connected to a rope knotted every 43.7’ was thrown overboard into the sea. One sailor would let the rope out; another would watch the sand glass. After 14 seconds, the number of knots would be multiplied by two to learn the speed of the ship. The first mention of a sand glass and ship log was in 1574; however the tool probably was used for some time before this date.
Currently not on view
Physical Description
wood (overall material)
glass (overall material)
sand (overall material)
overall: 4 1/2 in x 3 in; 11.43 cm x 7.62 cm
ID Number
catalog number
accession number
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Work and Industry: Maritime
Maritime Objects
Data Source
National Museum of American History


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