William Crookes was a physicist, chemist, entrepreneur and spiritualist. Being a consummate experimenter he designed precision instruments of great delicacy, in particular exquisite glass vacuum tubes. The radiometer, when first exhibited in 1875, took the scientific world by storm, and became his trade mark. Other artefacts in the Science Museum collection include a spiral model of the periodic table of elements, sun spectacles, and a portrait of his medium Florence Cook. His train of thought has been recorded not only through his scientific papers but through the development of his beautiful instruments.