Mercer 2 day chronometer
Thomas Mercer 2 day survey chronometer with contacts.
The chronometer as invented by Harrison in the late 18th century and then perfected over the next few decades remained virtually unchanged until the introduction of the quartz clock. This is a relatively young model and on the outside it does not look like it is a special clock. The casing is typical of the period being enameled metal. However, the chronometer itself is still the customary high-precision brass artwork one can expect from these instruments.
What makes this instrument special is that it has been designed specifically for surveying. It has two contacts that allow an electronic device to be connected such as a light or buzzer (or chronograph). The outputs are driven by a mechanical-electrical contact in the clock. With every second the contact is closed for a brief moment. The only exception is the full minute which does not give a contact. This could be a defect in this chronometer but it would be logical to allow counting the minutes.
The instrument is nog gimballed but the clockwork can be locked for transport. The instrument is probably a former UK Hydrographic Office instrument used for longitude determination of a baseline.
More information
Mercer-2-day
Data sheet
- Year
- ca 1958
- Serialnumber
- 23251
- Type of use
- Survey
- graduation
- s
- measuring range
- 56 hours
- accuracy
- 0.2
- fine reading
- direct (analog)
- Size instrument (Ø x h) in m
- 0.16 x 0.09
- weight instrument in kg
- 2.1
- Size case (l x w x h) in m
- 0.22 x 0.28 x 0.18
- weight case & in kg
- 3.5
- country obtained from
- United Kingdom
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Thomas Mercer 2 day survey chronometer with contacts.