All of the Prerogative Wills of Ireland were destroyed by a fire in the Dublin courthouse in 1922, but before that Sir William Betham had made abstracts of the genealogical data in the wills from 1536 to 1800. In 1897 Sir Arthur Vicars prepared this index to Betham's abstracts. The index has 40,000 entries arranged alphabetically by the name of the testator, showing his rank, occupation, or condition; his town or county of residence; and the year when the estate was probated. In view of the loss of the original wills, this is one of the most useful tools in all of Irish genealogical research.