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

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
Object Name
sand glass, 14 second
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
See more items in
Work and Industry: Maritime
Maritime Objects
Data Source
National Museum of American History, Kenneth E. Behring Center


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