The subjects (outside those required for his professional work) in which he took most interest were Poetry, History, Theology, Antiquities, Architecture, and Engineering. He was well acquainted with standard English poetry, and had committed large quantities to memory, which he frequently referred to as a most valuable acquisition and an ever-present relief and comfort to his mind. History and theology he had studied as opportunity offered, and without being widely read in them he was much at home with them, and his powerful memory made the most of what he did read. Antiquities and architecture were very favourite subjects with him. He had visited most of the camps and castles in the United Kingdom and was never tired of tracing their connection with ancient military events: and he wrote several papers on this subject, especially those relating to the Roman invasions of Britain. Ecclesiastical architecture he was very fond of: he had visited nearly all the cathedrals and principal churches in England, and many on the Continent, and was most enthusiastic on their different styles and merits: his letters abound in critical remarks on them. He was extremely well versed in mechanics, and in the principles and theory of construction, and took the greatest interest in large engineering works. This led to much communication with Stephenson, Brunel, and other engineers, who consulted him freely on the subject of great works on which they were engaged: in particular he rendered much assistance in connection with the construction of the Britannia Bridge over the Menai Straits. There were various other subjects which he read with much interest (Geology in particular), but he made no study of Natural History, and knew very little about it beyond detached facts. His industry was untiring, and in going over his books one by one it was very noticeable how large a number of them were feathered with his paper "marks," shewing how carefully he had read them and referred to them. His nature was essentially cheerful, and literature of a witty and humourous character had a great charm for him. He was very fond of music and knew a great number of songs; and he was well acquainted with the theory of music: but he was no performer. He did not sketch freehand but made excellent drawings with his Camera Lucida.