56-hour marine chronometer
Date: 1855-1881
Inventory Number: 1998-1-1320
Classification: Chronometer
Subject:
Maker: John Poole (fl. 1826 - 1881)
User: Oak Ridge Station (1931 - 2005)
User: George R. Agassiz Station, Harvard (1951 - 1982)
User: Harvard College Observatory (founded 1839)
Cultural Region:
Place of Origin:
Dimensions:
instrument: 15.3 × 15.9 × 7 cm (6 × 6 1/4 × 2 3/4 in.)
case: 19.2 × 21.6 × 20 cm (7 9/16 × 8 1/2 × 7 7/8 in.)
DescriptionChronometer in mahogany case, 56 hour duration, with instructions for care pasted on inside lid of case.
The chronometer is gimbal mounted inside a box with the traditional double lid of a chronometer case. The top lid is solid wood; the lower lid has glass on top. The gimbals have a brake and locking screw. The winding key is in the box. The box has a latch operated by a sliding button. The corners of the box are reinforced with brass. There are two brass handles on the sides of the box. Green felt is glued to the underside of the box (probably a later addition).
The chronometer's dial has hours marked I-XII with divisions every minute around the face. The upper circle inside the hour scale shows hours remaining until the clock will wind down, 0-54, graduated every 6 hours. It is marked "WIND," "DOWN," and "UP." The lower inner circle shows seconds 0-60.
The brass name plate of the box is blank. A hard rubber plate for the serial number is also left uninscribed.
The chronometer is gimbal mounted inside a box with the traditional double lid of a chronometer case. The top lid is solid wood; the lower lid has glass on top. The gimbals have a brake and locking screw. The winding key is in the box. The box has a latch operated by a sliding button. The corners of the box are reinforced with brass. There are two brass handles on the sides of the box. Green felt is glued to the underside of the box (probably a later addition).
The chronometer's dial has hours marked I-XII with divisions every minute around the face. The upper circle inside the hour scale shows hours remaining until the clock will wind down, 0-54, graduated every 6 hours. It is marked "WIND," "DOWN," and "UP." The lower inner circle shows seconds 0-60.
The brass name plate of the box is blank. A hard rubber plate for the serial number is also left uninscribed.
In Collection(s)
Signedon face: John Poole / MAKER TO THE ADMIRALTY / 57 Fenchurch St. London
Inscribedserial number on face: 2096
FunctionA marine chronometer was used on a ship to keep the time from the port of origin or an established zeroth longitude (such as Greenwich, England) while at sea. With that data, ships were able to find the longitude anywhere on the ocean by simply determining the time at their current position.
Curatorial Remarkstag: Frame maker/ Finisher G.H.
tag: Very dirty / oil oxidized / Do not run / unless overhauled.
tag: Very dirty / oil oxidized / Do not run / unless overhauled.
ProvenanceHarvard College Observatory; transferred from Agassiz Station to CHSI, 21 May 1969.