Account book of William Williams of Llandegai. Mainly dealing with the quarry and the slate trade: slates delivered, names of boats and masters, sums due, money paid for cartage, payments made "on Acct. of the ....Quarry", such as the £2.18.10½ "to pay the men for opening the bottom of the Quarry to get to the joints of the Rocks", 10/6 to Joseph Thomas "for making a Beam to weigh Slates", 4/- to William Jones of Talybont for carrying sand from Traeth y Lafen to the quarry, &c. Also, a letter to Richard Pennant, esq., [not yet created Lord Penrhyn] of the 14 August, describing the progress of repairing the road at both ends of the Cletffrwd bridge, and the "sulphur" found at Briach Ty Du and Ciltwllan. January - November 1783