Mapping of Ireland

Recorded mountains
 to 1700

 The mountains of Ireland appeared and were named on maps of the island as early as 1572.

John de Courcy has detailed the summits that appear on maps up to 1700.

(see Mountaineering Ireland. IMEHS Journal, Vol 2, 2005)

Charles Vallencey produced a military survey
of parts of the island around 1780.

Various land owners produced estate maps of their property and it was William Edgeworth, who had been involved in the Bogs Commission survey, that produced a trigonometrical survey of Co Longford and part of Roscommon. With him, 'native Irish cartography attained a new high level'.  Alexander Nimmo, for the same survey, produced a comprehensive map of the Kerry region in 1811.

                    

                                                      

See Finnian O Cionnaith Land Surveying in Ireland 1690-1830  for details of earlier surveyors.

      

In 1824 the six-inch Ordnance Survey mapping of Ireland was begun under Thomas Colby. As a consequence the surveyors were the first group to systematically get to all the significant mountain summits on the island. 

Principal triangulation
with dates.

 There is hardly a prominent peak that does not bear evidence of this in the ubiquitous 'trig pillars' that are familiar to hikers and are the result of 'retriangulation' carried out in the 1950s and '60s. 

Ireland was the first country to be completely mapped at a scale of  6 inches to a mile.

Much discussion  took place as to the merits of contour lines or hachuring to represent altitude and slope and it was not until about 1890 that the complete hill edition was produced.

A full account of the operation and proceedings of the OS in 19th Century Ireland is given by 

JH Andrews in  A Paper Landscape.

Thomas Colby was the director of the OS in Ireland  and John O' Donovan played 

John O'Donovan

an important role in the toponymical aspects of the survey.

Of course, the surveyors climbed the mountains for professional reasons rather than for recreation.  However, their activities may have had an influence on a generation of people that became interested in the activity of surveying, some of whom carried this interest abroad to Europe and North America and carried out surveys of their own in these places.  Among such people were John Palliser, Anthony Adams Reilly, Edward Oliver Wheeler and there will be more about these to follow.

A fascinating 'biography of the Ordnance Survey' is Map of a Nation by Rachel Hewitt (Granta, 2010)

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