This book is a biography of William Hyde Wollaston, a trained physician who became one of Britain’s leading natural philosophers in the early nineteenth century. During his lifetime he achieved an international reputation in chemistry, linear optics and mineralogy and was judged to be one of the most acute experimental philosophers of his age. He is best known for the preparation and commercial sale of malleable platinum, but he was also an active scientific entrepreneur who prepared and sold organic chemicals to the textile manufacturers of Manchester, and patented two optical devices. He moved effortlessly between endeavours we now distinguish as pure and applied science, and was criticized by some for such versatility. Wollaston made an astonishing number of original observations and discoveries, such as (in approximate chronological order) the fungal cause of grass circles known as fairy rings, the identity of common and voltaic electricity, the dark lines in the solar spectrum, the existence of ultraviolet light, the chemical elements palladium and rhodium, the amino acid cystine, multiple combining proportions, high frequency hearing loss, and just missed out on isomorphism and electromagnetic rotation. He also introduced several novel instruments and devices, such as a refractometer, the camera lucida, the reflective goniometer, the scale of chemical equivalents, and is eponymously remembered by Wollaston wire and the Wollaston doublet. He lived in the period of astonishing social change known as the English Industrial Revolution and is a paradigmatic example of the individualism that so invigorated British society in Georgian times.