Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Furnishings and Equipment (hierarchy name)
4. Measuring Devices (hierarchy name)
5. measuring devices (instruments)
6. [measuring devices for extent]
7. timepieces
8. [timepieces by form]

Narrower term/s

• hourglasses

Anotations

Scope note:

Timepieces that measure equal periods of time by the motion of sand or other freely flowing, fine-grained substances through a narrow aperture between two triangular or conical glass bulbs arranged mouth to mouth; probably introduced in the early 14th century and used then especially for timekeeping aboard ships.