formed also a collection of the mineral productions and rocks of that country, which he presented to the Geological Society in 1814. In that year he was appointed geologist to the Trigonometrical Survey; and in 1816–1818 he was president of the Geological Society. Comparatively little had been done in the investigation of Scottish geology, and finding the field so full of promise, he devoted himself to its cultivation with great ardour. One of his most important labours was the examination of the whole range of islands along the west of Scotland, at that time not easily visited, and presenting many obstacles to a scientific explorer. The results of this survey appeared (1819) in the form of his Description of the Western Islands of Scotland, including the Isle of Man (2 vols. 8vo, with an atlas of plates in 4to), which forms one of the classical treatises on British geology. He appears to have been for a time on the board of the Quarterly Journal of Science, Literature and the Arts, which was published at the Royal Institution of Great Britain. He was elected FRS in 1820. He continued to write papers, chiefly on the rocks and minerals of Scotland, and had at last gathered so large an amount of information that the government was prevailed upon in the year 1826 to employ him in the preparation of a geological map of Scotland. From that date up to the time of his death he returned each summer to Scotland and traversed every district of the kingdom, inserting the geological features upon Arrowsmith's map, the only one then available for his purpose. He completed the field-work in 1832, and in 1834 his map and memoir were ready for publication, but these were not issued until 1836, the year after he died. Among his other works the following may be mentioned: A Geological Classification of Rocks with Descriptive Synopses of the Species and Varieties, comprising the Elements of Practical Geology (1821); The Highlands and Western Isles of Scotland, in a series of letters to Sir Walter Scott (4 vols. 1824); A System of Geology, with a Theory of the Earth and an Examination of its Connection with the Sacred Records (2 vols. 1831); Proofs and Illustrations of the Attributes of God, from the Facts and Laws of the Physical Universe: Being the Foundation of Natural and Revealed Religion (3 vols. 1837). He also