The most useful manuscripts in the Genealogical Office collection are those acquired and created to provide sources for genealogical research. The policy was begun in the early nineteenth century by Sir William Betham and was continued by his successors, and it has produced a wide range of material, much of it based on records that were destroyed in the Public Record Office in 1922. It may be divided into three broad categories:
The sheer diversity of these documents makes a complete account impractical here; what follows is a broad outline.
The greatest work produced by Betham is the collection of abstracts of family information from prerogative wills. These are divided into a number of series. GO 223-6 ('Old Series', Vols. 1-4) covers wills before 1700, and GO 227-54 ('New Series', Vols. 1-31) covers wills from 1700 to c.1800. The series is roughly alphabetical, with each volume containing its own index. Sir Arthur Vicars's Index to the Prerogative Wills of Ireland, 1536-1810 (online at www.archive.org) provides a guide to wills covered. Many of the sketch pedigrees include later amendments and additions from other sources. GO Mss. 255-6 index all the marriage alliances recorded in the wills. Another series, GO 203-214 ('Will Pedigrees', Vols. 1-12), represents an unfinished attempt to rearrange all these sketch pedigrees into strictly alphabetical order. Betham also produced a large number of sketch pedigrees based on other sources, collected as 'Ancient Anglo-Irish Families', Vols. 1-6 (GO 215-19), 'Milesian Families', Vols. 1-3 (GO 220-22), and the '1st series', Vols. 1-16 (GO 261-76), and '2nd series', Vols. 1-7 (GO 292-8). These are all indexed in GO 470.
Betham Sketch Pedigree: The Wright family of Gola [Courtesy of The Genealogical Office]
As well as the sketch pedigrees and the letters (covered above under 'Administrative records and reference works') there are two other sources in the collection that owe their origin to Betham. The first of these, genealogical and historical excerpts from the plea rolls and patent rolls from King Henry iii to King Edward vi (GO 189-93), constitute the most important source of information on Anglo-Norman genealogy in Ireland. Betham's transcript of Roger O'Ferrall's 'Linea Antiqua', a collation of earlier genealogies compiled in 1709, is the office's most extensive work on Gaelic, as opposed to Anglo-Irish, genealogy. This copy (in three volumes, GO 145-7, with an index to the complete work in GO 147) also contains Betham's interpolations and additions, unfortunately not giving sources. It records the arms of many of the Gaelic families covered, without giving any authority for them, and is the source of most of the arms illustrated in MacLysaght's Irish Families.
Pedigrees and research notes produced by later amateur and professional genealogists make up a large part of the office's manuscript collection. Among those who have contributed to these are Sir Edmund Bewley, Denis O'Callaghan Fisher, Arthur Tenison Groves, Alfred Molony, T.U. Sadleir and the Rev. H.B. Swanzy. For the most part their records concern either particular groups of families or particular geographical areas. Some of these have their own indexes, some are covered by GO 470 and 117, and others have will abstracts only indexed in GO 429.
As well as these, some of the results of Ulster's own research in the late nineteenth
and early twentieth centuries are classed as manuscripts, GO 800-822. These
constitute no more than a fraction of the total research information produced by
the Genealogical Office. They are indexed in Hayes's Manuscript Sources.
A final class of records consists of extremely diverse documents, having only
their potential genealogical usefulness in common. It includes such items as
freeholders' lists from different counties, extracts from parish registers,
transcripts of the Dublin city roll of freemen, transcripts of returns from the 1766
census, transcripts of city directories from various periods and militia lists. The
most useful of these are referred to in the county source lists.