John Tyndall (1820-93) was an influential Irish geologist who became fascinated by mountaineering after a scientific expedition to Switzerland in 1856. He joined the Alpine Club in 1858 and achieved the summit of the Matterhorn in 1868 - a feat which led to a peak on the Italian side of the massif being named after him. He also climbed Mount Blanc three times. A writer of scientific texts who was widely praised for the quality of his prose, Tyndall...