As a naturalist he had a great curiosity, observing the geography, geology, plants, animals, birds, reptiles, amphibians and fish around him and recording what he saw and heard about. He wrote acclaimed books including British Zoology, the History of Quadrupeds, Arctic Zoology and Indian Zoology although he never travelled further afield than continental Europe. He knew and maintained correspondence with many of the scientific figures of his day. His books influenced the writings of Samuel Johnson. As an antiquarian, he amassed a considerable collection of art and other works, largely selected for their scientific interest. Many of these works are now housed at the National Library of Wales.
As a traveller he visited Scotland and many other parts of Britain and wrote about them. Many of his travels took him to places that were little known to the British public and the travelogues he produced, accompanied by painted and engraved colour plates, were much appreciated. Each tour started at his home and related in detail the route, the scenery, the habits and activities of the people he met, their customs and superstitions and the wildlife he saw or heard about. He travelled on horseback accompanied by his servant, Moses Griffiths, who sketched the things they encountered, later to work these up into illustrations for the books. He was an amiable man with a large circle of friends and was still busily following his interests into his sixties. He enjoyed good health throughout his life and died at Downing at the age of seventy two.
Members of Aboriginal, Torres Strait Islander and Maori communities are advised that this catalogue contains names and images of deceased people. All users of the catalogue should also be aware that certain words, terms or descriptions may be culturally sensitive and may be considered inappropriate today, but may have reflected the author's/creator's attitude or that of the period in which they were written.