Do a frequency and distribution study by using Mathesons Special Report on Surnames of Ireland which shows surnames with five or more entries in the birth indexes of 1890, and the main counties in which they were found. The birth rate was 1:44 at that time so you can estimate the number of people of the name at that time. The great value of Matheson's report is that it indicates how common a particular surname is countrywide, provincially and also in a county. The distribution of surnames has not changed significantly since the publication of the Report - so it is reasonable to presume the same pattern prior to 1890. http://www.rootsweb.com/~irish/ir-names/math-nam.htm Ellen