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Documenting the Cultural Heritage
Standards in Practice: Greenwich
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Sample Record 4:
Object ID

John Harrison's marine timekeeper H4 John Harrison’s
marine timekeeper, H4
(© National Maritime
Museum, Greenwich,

1.1 Photographs National Maritime Museum — A 6269
1.2 Type of Object
Level 1:
Level 2:

1.3 Measurements 13.2 cm diameter, 5.5 cm deep; 1.45 kg weight
1.4 Materials & Techniques Silver, brass and steel; glass; enamel on copper dial; diamonds and rubies in the bearings; silk lining to the case
1.5 Inscriptions & Markings Signed "John Harrison and Son, London AD 1759" on the movement; silver hallmarks on the outer (dated 1759) and inner (dated 1758) cases; makers’ marks on the outer ("HT") and inner ("IH") cases
1.6 Date or Period 1759
1.7 Maker John Harrison and Son, London
1.8 Subject  
1.9 Title Marine timekeeper, H4
1.10 Distinguishing Features There is a crack in the enamel of the dial and a triangular chip in the enamel near the case bolt
1.11 Description A marine timekeeper in the form of a silver pair-cased watch, with a brass and steel fusee movement with Harrison’s verge escapement with diamond pallets. The watch represents the successful conclusion to Harrison’s work in developing a high-accuracy, portable, marine timekeeper, enabling the establishment of longitude at sea. It is the first precision watch
2.1 Object ID No. National Maritime Museum — ZAA 0037
2.2 Related Written Material NMM departmental file; J. Betts, Harrison, London, 1993; R.T. Gould, The Marine Chronometer — Its History and Development, London, 1923; H. Quill, John Harrison, the Man Who Found Longitude, London, 1966
2.3 Place of Origin/Discovery England
2.4 Cross Reference to Related
This is one in a sequence of 5 prototypes of which H4 was the successful conclusion and H5 was a similar model, based on H4. H1, 2 and 3 are in the National Maritime Museum; H5 is at the Worshipful Company of Clockmakers, Guildhall, London
2.5 Date Documented 25th March 1998

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