Irish Roots

Glory be to the Ordnance Survey

A few weeks back, the Ordnance Survey Ireland maps website ( was taken offline and the worldwide Fraternity of Historic Map Nuts held its breath. For the past five years, the OSI site has provided free, world-class access to current and historic Irish Ordnance Survey maps, layering one over the other, so that users can peel back the present with a simple movement of a slider bar, and watch wonderful, 200-year-old detail slowly come to the surface.

The quality of the site was perfectly in keeping with OSI's history. Set up in 1824 as part of the great process of measuring Ireland that followed the Act of Union, the vast mapping survey was unprecedented anywhere in the world. It was done in the teeth of controversies about scale, contouring, field boundaries, and in spite of government penny-pinching, spectacular bureaucratic infighting and the usual Irish personality clashes (for a blow-by-blow account see JH Andrews' A Paper Landscape, repr. Four Courts Press, 2006).

What resulted were the best maps in the world. Their quality was largely due to the tenacity and integrity of the two English officers who drove the organisation, Colonel Thomas Colby and his subordinate, Captain Thomas Larcom. With several thousand surveyors in the field, and hundreds of cartographers and engravers at headquarters in Mountjoy in the Phoenix Park (still OSI's head office), Larcom created a unique map-making factory. He was punctilious about the smallest details – Oliver Goldsmith's house and tree, Dean Swift's Glebe – and demanded precise measurement of every townland. He also wanted the maps to be beautiful, and they are.

So when the website came back online two weeks ago, and the historic layers were missing, a horrible sense of dread gripped the Fraternity. But then, last week, they were restored, with even more historic layers, even faster response times and even better magnification. The hosannas were audible from Addis Ababa to Ulan Bator.