Letter: West of Greenwich

THE French are not all longitudinally nationalistic (letter, 10 April). The small rural commune of Chalandray, about 15 miles north-west of Poitiers, has for many years caught the eye of motorists speeding though on the busy N149 by a smart sign outside La Poste: "Ici passe le Meridien de Greenwich".

Ironically it is Britain which is, in a real way, still divided on "which meridian?" Since 1884, the world's "Longitude 0" has been that which the seventh Astronomer Royal, George Airy, established at the Royal Observatory, Greenwich, in 1851. But since the Ordnance Survey, begun in the 1780s, declined to adjust British land maps to it for practical reasons, these are still based on the third Astronomer Royal James Bradley's zero meridian of 1750 - which at Greenwich is 19 feet to the west.

PIETER van der MERWE

National Maritime Museum Greenwich

London SE10