Tyndall has been described as “the greatest experimental physicist of the Victorian age” for his wide-ranging work, and was the first to prove the greenhouse effect. Frankland and he met as young teachers, and studied together under Bunsen in Marburg. He collaborated with Knoblauch (one among his huge range of correspondents, many German) and researched in Magnus’s Berlin laboratory. A member of Huxley’s ‘X-Club’, he was greatly admired by his friend Faraday, translated Helmholtz, defended Pasteur, and tangled with Joule. A great climber and hiker, he visited Muir at Yosemite, and wrote to his friend Darwin about mucus and nostril-hair.