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Sample
Record 4:
Object ID |
 |
John
Harrisons
marine timekeeper, H4
(© National Maritime
Museum, Greenwich,
London) |
|
| 1.1 |
Photographs |
National
Maritime Museum A 6269 |
| 1.2 |
Type
of Object
Level 1:
Level 2: |
Timekeeper
Chronometer |
| 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 Harrisons
verge escapement with diamond pallets. The watch represents
the successful conclusion to Harrisons 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
Objects |
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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