The online Archive of the Month from the Representative Church Body Library (RCBL) is a Preacher Book, compiled 1841–1863 in the parish of Clones, Co Monaghan, which has been scanned to pdf format for free download.
Such Preacher Books were part of the standard administrative records produced and maintained by Church of Ireland parishes. They typically record details of each service given, the name of the preacher and reader, the size of the congregation, the sum of money collected, and 'observations'. The latter range from explanations for an unusual or unexpected size of congregation (bad or good weather, local events etc) to occasional mention of genealogical events.
For more about Preacher Books and their potential genealogical value, see the presentation by genealogist Maeve Mullin on the RCBL Archive page.