MERTHYR TYDFIL, or MERTHYR TYDVIL  , a municipal,

county and parliamentary borough, and market-town of Glamorganshire, south Wales, situated in a bleak and hilly region on the river Taff, on the Glamorganshire Canal, and the Brecon and Merthyr, Great Western, North Western, Taff Vale and Rhymney railways, 25 M . N.N.W. of Cardiff, 30 E.N.E. of Swansea, and 176 from London . Pop . (Igor), 69,228 . The town is said to have derived its name from the martyrdom of St Tydfil, daughter of Brychan, who was put to death by Saxons in the 5th century . It is for the most part irregularly built and was formerly subject to severe epidemics due to defective sanitation; but it now possesses a supply of the pu,,,rest water from the lesser Taff on the southern slope of the Brecon-'shire Beacons . The town owes its early industrial prosperity to the abundant ironstone and coal of the district, and it thus became at an early date the chief seat of the iron industry in Wales . Four great ironworks were established here between 1759 and 1782 . With the earliest, that of Dowlais, the Guest family were associated, first as partners and later as sole owners from 1782 to 1901 when the works were disposed to the company of Guest, Keen and Nettlefold . In 1765, Cyfarthfa was started by Anthony Bacon, and when firmly established, sold in 1794 to Richard Crawshay by whose descendants the works were carried on till the owners formed themselves in 1890 into a limited company (Crawshay Brothers Cyfarthfa Limited), the controlling interest in which has since been acquired by the Dowlais Company . The Plymouth works, started soon after Cyfarthfa, by Wilkinson and Guest, passed later into the hands of Anthony Hill from whose descendants they were purchased in 1863 . on the northern limits of his lordship of Glamorgan, its erection causing a serious feud between him and de Bohun, earl of Hereford, who claimed its site as part of the lordship of Brecknock .

(D . LL .