An index on paper slips, in J. Lloyd Williams's hand, of folk tunes and songs found mainly in the work of Nicholas Bennett. References supporting his candidature for the Chair of Botany at Aberystwyth in 1903 appear on the verso of some slips.
Lists of titles of tunes from manuscripts held at the National Library of Wales, and extracts relating to Welsh music; together with 'A list of the most important collections of Welsh Traditional Songs'.
Manuscript and typescript drafts and an annotated printed copy of the libretto; together with stage directions and a synopsis of the plot. A copy of the printed programme of a performance of the work at Aberystwyth in 1922 is also included.
An unbound copy, [?1944], of Y Tri Thelynor, and two annotated typescript drafts. Correspondence, 1943-1944, relating to the publication of the work, together with photographs and miscellaneous notes, are also included.
A typescript copy of a lecture entitled 'Congregational singing in Nonconformist Wales', delivered by J. Lloyd Williams at Harlech in August 1941; an exercise book containing an address/lecture entitled 'Caniadaeth y Cysegr'; manuscript notes of a lecture on the same topic delivered at Trawsfynydd in 1929, Treherbert, 1940 and Ystradgynlais, 1941; notes of lectures relating to hymn tunes given in 1938 and 1942; and preparatory notes for the president's address at a singing festival in Aberystwyth, April 1917.
A bundle of notes entitled 'Welsh Nat. Music', comprising extracts from Seren Gomer, 1819-1849, notes on the history of the Gwyneddigion, 'penillion' singing, and a list of Welsh airs which appeared in Y Cerddor, 1893. A summary of contents of Cambrian Minstrelsie, 1893-1895, is also included.