This sixth volume of Tyndall’s correspondence contains 302 letters covering a period of twenty-eight months (1856-1859). It begins shortly after Tyndall returned from his first glacier research in the Alps and follows him as he experimented and lectured on physics in central London at the Royal Institution of Great Britain (RI), visited friends, joined London’s fashionable social circles, published and reviewed scientific articles, corresponded with fellow men of science on a wide range of topics, and developed his theories about the structure and movement of glaciers. Importantly, volume 6 includes Tyndall’s major expeditions to the Alps and also documents some of his most dangerous mountaineering exploits. In letters to his closest friends, Tyndall captured the excitement and achievement of his expeditions. By the end of the period, his is increasingly respected as a scientist in the wider academic world.