What is a ordnance survey map What does it show?

Ordnance survey maps are maps that show altitude in relation to a 'known' ordnance datum. An ordnance datum is a point of particular altitude. In the UK, that ordnance datum for ordnance survey maps...

An OD (Ordnance Survey) map are maps that were originally used for the military. It was produced by following a series of surveys. Hope this helps. :)

During the English civil war Oliver Cromwell, leader of the Parliamentarian side discovered that he had great difficulty hitting anything with his artillery.He realised that the root of the problem...

it means ......The Ordnance Survey National Grid reference system is a system of geographic grid references used in Great Britain, different from using latitude and longitude.

The origins were in 1747, Colonel David Watson proposed a map of Scotland to help defeat the Scottish Clans after the Jacobite Uprising of 1747