A song entitled 'Cân i Chwarel y Penrhyn' composed by Robert Jones ('Llystyn') and presented to the Penrhyn Slate Quarry Harmonic Society, 1859.

Dyddiadur y Methodistiaid Wesleyaidd ... 1891, containing entries, in Welsh, by Owen Thomas, ?Tre-garth, parish of Llandygái, co. Caernarfon, mainly comprising reflections on his spiritual condition, and including (p. 36) a reference to his fellow-workers ('fy nghyd-weithwyr') at the Penrhyn slate quarry.

Sixty-five holograph and autograph letters and postcards, and telegrams, 1888-1913 and undated, addressed to David Robert Daniel (1859-1931) of Fourcrosses, Chwilog, Caernarvonshire. The writers include a circular, 1904, issued by the North Wales Quarries Ltd; P[eredur] Ll. Daniel, London, his son, undated; [Robert Evans] ('Cybi'), Llangybi, undated; [E.] Vincent Evans, London, 1913?; [Henry] Harold Hughes, Bangor, 1903-06; and The North Wales Quarrymen's Union, Caernarvon, undated. Also included in the group are three holograph letters, 1888-1905, from D. R. Daniel to his wife Sara and to his mother Jane; a holograph letter, undated, from Sara [Daniel] to her mother at Llandderfel; a grand jury summons for the General Quarter Sessions of the Peace for Caernarvonshire, addressed to D. R. Daniel,1905; vouchers, certificates of bank credits, etc. of D. R. Daniel, 1904-13; and other holograph letters which include one to [H. J. Williams] ('Plenydd'), 1890; and a letter, 1898, containing accounts of the North Wales Quarrymen's Union; also verses in Welsh entitled 'The Memorable Temperance Supper Dec. 23rd. 1882'.
References include those to Peredur Daniel, son of D. R. Daniel; memorials and a Testimonial Fund to Thomas Edward Ellis; the illness of Daniel's father-in-law; and the Penrhyn Quarry dispute.

A group of miscellaneous deeds and documents, including a bond, 1748/9, from Edward Jones of Llwyn malli, parish of Llangwm, Denbighshire, to Roger Thomas of Henvache, parish of Llanrhaiadr yn Mochnant, for the payment of £61 7s. 0d.; a bond, 1760, from Edward Jones of Rhosynwst, parish of Llantysilio, Denbighshire, and Maurice Jones, his eldest son and heir apparent, to Edward Frank of Crumpwell, Salop, for the payment of £320; a settled statement of account, 1767-1774, between Maurice Jones and Mr. Edward Frank, touching the payment of a principal of £650 and interest; bills of costs, 1800-1827, due from Morris Edwards and Robert Jones for the conveyance of properties in Bala, etc.; notices of tithe audits for the parish of Llantisilio, Denbighshire, 1847-1863, addressed to Godfrey Tudor and John Tudor of Pentredwr, Llantisilio, and receipts for the payment of poor rate and general district rate in respect of Bache Farm, parish of Llangollen, 1859-1862; a receipt, 1855, from Thomas Edwards, Llangollen, to John Tudor, on behalf of the congregation of the Methodist chapel of Pentre'r dwr, for the payment of £3 10s. 0d. for an eight-day spring piece; vouchers, 1859-1860, to John Tudor, Pentredwfr, from the Llangollen Slab & Slate Co. Ltd., and William Clarke, general furnishing ironmonger, Llangollen; a lease, in Welsh, 1876, from Richard John Lloyd Price of Rhiwlas, Merioneth, to Margaret and Catherine Edwards of Penybont fawr, Merioneth, of properties called Penybont fawr, Penybont bach, etc., in the parishes of Llanfor, Llangower, and Llanycil, Merioneth; a voucher, 1876-1877, to Miss Edwards of Penybont from Robert Humphreys, stater, in respect of repairs to houses in Bala; undated [after 1922] typescript memoranda by Dr. Bradley Hughes, Penrhyn Quarry Hospital, Bethesda, N[orth] Wales, on the effect of slate dust on the toxins of microbes; and a typescript copy of a letter, 1926, from John Gill, c[ivil] e[ngineer], Bangor, to the Chairman and Members of the Ogwen Rural District Council, Bangor, regarding the water supply of the districts of Tregarth and St. Anns.