1693 CE–1776 CE
John Harrison
Oceans, navigation & cartography · Instruments & positioning
An English carpenter and clockmaker, Harrison developed a series of timekeepers able to preserve an accurate time reference at sea. His work made longitude calculation through the difference between reference and local time practical, although broad adoption depended on copies, trials, costs, and naval institutions.
Precision, calendar, and review
- Start
- year · no uncertainty qualifier in this record
- End
- year · no uncertainty qualifier in this record
- Calendar and convention
- Historical-era years; the source calendar is not identified. No conversion of days is assumed.
- Year zero
- The scale goes from 1 BCE to 1 CE without year zero. Changing era names changes labels only.
- Documentary review
- Date not recorded
Reading the date: life span.
Sources
- www.rmg.co.uk (opens in a new tab)
Source provenance and scope
- Publication date
- Not identified in metadata; document review pending
- Bibliographic date checked
- 2026-09-23
The correspondence between this reference and individual claims has not yet been itemized.
This record is an editorial synthesis. Consult the sources to check claims and their limits. Chronological relationships alone do not establish causation.