
4 0 c m
32cm
actual image size: 24cm x 32cm
Description
"Wooden, 55 second sand glass from the second half of the 18th century. Sand glasses were made to measure out a specific length of time. They were used at sea to time a ship's 'watch', or to calculate the ship's speed."
Image Details
Image Ref.
10422470
© Science Museum / Science & Society Picture Library