In 1941, National Library Director Richard J. Hayes launched a vast cataloguing and indexing project which would run for over 30 years.

Hayes recognised that the National Library should collect "all sources of information on everything relating to Ireland or to Irishmen for all periods". In support of that vision, he established a project to list irreplaceable Irish manuscripts, wherever they were found, and to index the content of the most important Irish journals. Researchers were dispatched to over a thousand libraries and archives in 30 countries to find, record, and in many cases microfilm manuscript material. They uncovered close to 100,000 manuscripts, from the smallest of remote monasteries to the vast collections of the National Library itself.

Library staff also indexed every article, poem and review in key Irish periodicals published over the course of nearly 200 years, with the earliest dating from 1785. The journals indexed included those published by all the major learned and local societies and associations, trade and business interests, religious bodies, technical institutions and universities, as well as small literary magazines associated with writers such as WB Yeats.

The records they created were published as Manuscript Sources for the History of Irish Civilisation (1965, with a supplement in 1975, and continued by a card catalogue previously only available in the NLI's manuscripts reading room) and Sources for the History of Irish Civilisation: Articles in Irish Periodicals (1970). These amounted to 23 substantial volumes, containing over 17,000 pages of records. For decades, this huge resource has been of enormous value to anyone interested in Ireland and its people, but has only been accessible by visiting the limited number of libraries and universities who hold full sets of these printed catalogues.

This has all changed due to a major project that is part of the National Library's digital library programme. The records created by the original team of researchers have been digitised and encoded, and over 180,000 records for Irish manuscript and periodical material are now freely searchable online through this beta launch of Sources: a National Library of Ireland database for Irish Research.

See About The Project for more details on how this resource was developed.