As anyone who has suffered through a bad Powerpoint presentation can testify, there is a world of difference between written information and visual information. Pictures trigger an immediate reflex response: seeing a shark-fin coming towards you means a lot more than reading the word “Shark”.
I have recently discovered just how much more powerful pictures can be. The revamp in May of the Irish Ancestors site (irishtimes.com/ancestor) added a new service, individual surname maps. These maps are quite simple – they count every householder of a particular surname recorded in Griffith’s Valuation (1847 to 1864) and plot the numbers, parish by parish, onto a map of Ireland.
None of the information is new – it has been widely available in one shape or another for more than thirty years. But the impact of seeing geographic patterns emerge on the maps is extraordinary. Here are the 900 or so Redmond households, spreading out from the Norman invasion site over 20 or more generations (tinyurl.ie/9v8). Here are the Harkins, with a thick ribbon of settlement running along the north Donegal coastline (tinyurl.ie/9vt). If there was ever any doubt that the surname McMahon originated in two distinct areas, Clare and Monaghan, just look at the Griffith’s household map (tinyurl.ie/9va).
The problem is that it is almost impossible not to read elaborate stories into the images. Look, the Casserlys must have migrated east into Longford and Westmeath (tinyurl.ie/9vu). The Kilkenny Codys had just only begun to spread into East Cork by the 1850s (tinyurl.ie/9vc). The surname McNicholas must be relatively recent since it is so local (tinyurl.ie/9vd).
But is any of this true?. As ever in research, you have to keep your sceptical goggles on. Pictures like these can indeed reveal hidden patterns, but they can also make things obvious that aren’t really there.
['Irish Roots archive from 2009 at www.irishtimes.com/ancestor/magazine/column]