An interlinear translation into Welsh by Thomas Eurwedd Williams of the Greek text of sections 34-45 ('Croesus ac Adrastus'), 84-88 ('Croesus a Cyrus'), and 108-122 ('Cyrus, Astyages a Harpagus'), of the first book of the Histories of Herodotus, with short Greek-Welsh vocabularies at the end of each section; and a short Greek-Welsh vocabulary based upon Sophocles's Antigone.

'Geiriau Groeg-Cymraeg Chwanegol. Y Gyfrol Gyntaf a gynwysa 400 Geiriau Groeg Cymraeg Wedi eu Taflenu'n Gyfochrog yn Nghyd a Sylwadau ar Olion Ffug chwedlau Groeg yn Ofergoelion Cymru. Dilynwyd yr un Cynllun yn y Casgliad yma drwy daflenu y geiriau yn Gyfochrol gyda Nodiadau. Cynwysa'r Casgliad yma 400 Geiriau Cyfochrol Chwanegol . . .', being a glossary of approximately four hundred Greek words compiled by T. Eurwedd Williams, with notes in Welsh purporting to equate them with alleged Welsh cognates. The present volume appears to be a sequel to NLW MS 10680C compiled by the same author.