My research shows that there are three main sources for surnames in
Ireland. The first is a so called census in 1659 which was in fact an
abstract of names of persons paying poll tax; Griffith?s valuation
from 1848-1864, a property survey; and Matheson's Report on Surnames
in Ireland 1890.
University College Cork are currently undertaking a project using
these three sources and others to create an atlas of Irish Surnames.
Their website has an introduction to the project.
However, for some reason a report on the project is only available
through the Google cache in text format only. Part of the report lists
surnames in alphabetical order from 1659 census and Griffith?s
valuation. Third of the way down the page (part V)
To understand more about the 1659 census look at this page.
To understand more about Griffith?s valuation look at this page.
To see more pages of the report use this link. Click on ?Cached?. Near
the top click on ?Click here for the cached text only.?
Matheson's report is slightly limited in that it includes only
surnames having five or more birth entries and is post the large bulk
of Irish emigration. However, an alphabetical list of the first 100
appears on this site. You can buy a copy of the report through their
Irish Genealogical Society International
Robert Matheson, 1890 Birth Records
?This first list is based on the index of births for the year 1890,
and shows Murphy as the most common Irish surname, with about 62,600
bearing the name. The name Dwyer ranks 100 in the list, with about
Ancestry Ireland website has additional information on the Report and
a database of names.
I hope this answers your question. If it does not, or the answer is
unclear, then please ask for clarification of this research before
rating the answer. I shall respond to the clarification request as
soon as I receive it.