Oxford at the time, it proved full of inaccuracies, and he prepared a second edition, which was published after his death by W. Huddesford, Oxford, 1760, 8vo. In 1699 Lhuyd went to Scotland, and the following year to Ireland, thence returning towards the end of 1700 to Cornwall, where he spent three or four months studying Cornish. He was at first accompanied by William Jones, Robert Wynn, and David Parry, but the first left him in Cornwall. They were regarded with suspicion almost everywhere, being looked upon as conjurers in Pembrokeshire, while at Helston in Cornwall they were arrested as thieves (Pryce, Archæologia Cornu-Britannica). In 1701 he, with probably two of his companions, crossed to Brittany, and had been there scarcely three weeks when he was arrested at St. Pol de Léon as a spy, but after an imprisonment of eighteen days at Brest he was released on condition of leaving the country forthwith (Rowland, Mona Antiqua, pp. 315–17).
Returning to Oxford, he was created M.A. honoris causa by the convocation 21 July 1701, on condition that he should read six ‘solemn lectures upon natural history, one every year, during the space of six years.’ These lectures were published, under the title of ‘De Stellis Marinis,’ in a work of that name by J. H. Luick, Leipzig, 1733, fol., but were subsequently incorporated by Huddesford in his second edition of the ‘Lithophylacium.’ The next few years Lhuyd spent in arranging the results of his research, and in 1707, after much delay on the part of the printers, was published the first volume of his ‘Archæologia Britannica: an Account of the Languages, Histories, and Customs of Great Britain, from collections and observations in Travels through Wales, Cornwall, Bas-Bretagne, Ireland, and Scotland. Vol. i. Glossography.’ This volume consists of an elaborate ‘comparative etymology’ of the Celtic languages with Welsh, Irish, Cornish, and Breton grammars and dictionaries. At the commencement a list of the subscribers towards the author's travels is inserted, but we know from another source (Owen, British Remains, p. 152) that the whole amount subscribed within the five years was only 365l. 5s. Most of the subscribers were dissatisfied that the first volume should be purely philological (Hearne, Collections, ed. Doble, ii. 58), and no second volume appeared.
Lhuyd circulated in Ireland and Scotland some separate copies of his Irish-English dictionary from his ‘Archæologia Britannica,’ in order to obtain corrections. His dictionary is based upon a manuscript ‘Vocabularium Hibernicum et Latinum,’ compiled by Richard Plunket at Trim, co. Meath, in 1662, with additions from Keating's ‘Foras Feasa ar Eirinn,’ from Michael O'Clery's ‘Seanasan nuadh,’ from Sheridan's version of the Old Testament, and O'Donnel's version of the New Testament. It is preceded by an Irish grammar extracted from that of Francis O'Molloy and by a preface in Irish words, but with very few of the characteristics of Irish prose. The writer no doubt had the help of some native in writing it, but certainly not of a scholar. The Irish preface was translated by David Malcolm, and was published in 1732 in a prospectus of a proposed Gaelic dictionary (probably a reprint of Lhuyd's), and was subsequently included in a collection of Malcolm's ‘Letters, Essays,’ &c., London, 1738, 8vo.
In November 1708 Lhuyd was elected fellow of the Royal Society in spite of the hostility of Dr. Woodward. Woodward had quarrelled with Lhuyd respecting the origin of marine fossils, which Woodward had ascribed to the effects of the deluge. On 11 March 1709 Lhuyd was elected superior beadle of divinity, his friend Hearne retiring from the candidature in his favour (ib. ii, 175). But he did not long survive his election. He had suffered from asthma for many years, an attack of pleurisy supervened, and he died at the museum 30 June 1709. He was buried in St. Michael's Church, in the south aisle, appropriated to Jesus College, and known as the Welsh aisle, but no monument marks the spot.
Lhuyd is described by Hearne as a ‘person of singular modesty, good nature, and uncommon industry.’ He is often referred to by his contemporaries as ‘honest Lhuyd.’ When at home he lived a retired life at Eynsham, near Oxford, and was not in the least ambitious of preferment. The keepership of the museum was a ‘mean place, seeing there is no salary’ (ib. i. 244), and his chief source of income must have been the fees paid by visitors for seeing the curiosities (Owen, British Remains, pp. 151–2).
In addition to Lhuyd's two larger and best-known works already mentioned, he supplied some materials for Ray's ‘Synopsis Stirpium,’ Lister's ‘Conchyliorum,’ Baxter's ‘Glossary’ (which includes a posthumous tract by Lhuyd, ‘De Fluviorum, Montium, Urbium, &c., in Britannia nominibus’), Nicholson's ‘Historical Library,’ Hickes's ‘Thesaurus’ (Hearne, i. 55), Gibson's edition of ‘Camden's Britannia,’ and Collier's ‘Historical Dictionary.’ He is said to have had a hand in composing ‘Χοιροχωρογραφία, sive Hoglandiæ descriptio,’ Oxford, 1709, 8vo, in reply to Holdsworth's ‘Muscipula,’ which was a satire