28 diaries, entitled Y Dyddiadur Wesleyaidd, the Wesleyan diaries. The entries made by Thomas Williams contain information about preachers and the subjects of their sermons as well as notices of district meetings and other religious meetings. The lock-out at the Cae Braich y Cafn quarry in 1870 is recorded, as well as the religious revival of 1904 - 1905.
The printed information provided in the diaries is also of interest. There are Wesleyan notices of meetings and even lists and dates of fairs held throughout Wales.