DIEDERICK WESSEL LINDEN, M.D. IN a note on page thirty of Public Baths and Health in England, 16th 18th Century, the author Charles F. Mullett wrote: 'I regret very much my inability to find anything about Linden; so prolific an author deserves something better than silence'. Dr. Linden had in 1754 taken the waters at Llandrindod Wells and two years later published a treatise on those waters the very first detailed study of them. Having passed most of my life in the Radnorshire spa, I became interested in breaking into the silence said to surround him. First efforts were not encouraging. The Librarian of the Wellcome Institute of the History of Medicine in London wrote: 'I fear you have an elusive character in Dr. Linden. None of our standard biographical reference works so much as mention him in passing nor was the British Museum able to give more than a partial list of the Doctor's written works. The Librarian of the Royal College of Physicians stated: 'I have been unable to find any information whatsoever, except of a negative character, about Dr. D. W. Linden'. Gradually, however, from a variety of sources, the chief of which are noted in my bibliography, I was able to break a little way into the 'silence barrier' surrounding Diederick Wessel Linden, M.D., with the following results. In the 1859 edition of the History of Radnorshire by the Rev. Jonathan Williams, M.A., there occur in the section dealing with the parish of Llandrindod the sentences: 'This parish may with justice boast of the superior salubrity of its air and climature. It is the Montpellier of Radnorshire. In this parish are situated those medicinal springs of long-continued and approved celebrity, called Llan-y-drindod Wells. The principal of these are three, viz; the rock or chalybeate water, the saline pump- water, and the sulphur water.' But in the manuscript copy of this History written in the years just before 1818, and now in Hereford City Library, the reverend author continues: 'Having already given Dr. Linden's account of these much frequented waters, it may not be amiss to subjoin in this place the analysis of them which Dr. Williams, a very ingenious practitioner in the town of Aberystwyth, has lately favoured the public'. Dr. Richard Williams's book, An Analysis of the medicinal waters of Llandrindod, published in 1817, contains the sentence, 'Llandrindod has justly been considered as the Welsh Montpellier'. The Aberystwyth doctor is unlikely to have had any knowledge of the contents of the Rev. Jonathan Williams's Mss, which did not achieve print until 1859, and therefore one can fairly assume that both writers borrowed their reference to Llandrindod as another Montpellier from an earlier source. This source, I suggest, was 'A Treatise on the Three Medicinal Mineral Waters at Llandrindod in Radnorshire, etc', printed in London in 1756 for the author, Diederick Wessel Linden, M.D., who in the Introduction to his book says this of the air at Llandrindod, 'In short, it is such an Air as is required for sickly and declining Constitutions, and may be deemed the Montpelier of Great Britain'. This comparison of the Welsh spa with the French resort continued to be made down the years. The title page of the London version of The Cambrian Balnea,