The Campaign for Philosophical Freedom

Sir William Crookes (June 17, 1832 – April 4, 1919) was an English chemist and physicist. For most of his life he was a freelance chemical consultant, using a home laboratory. He was known for his investigations into cathode rays, and was a pioneer of vacuum tubes, inventing the Crookes tube and the Crookes radiometer. In 1861, Crookes discovered a previously unknown element and named it thallium (from the Greek thallos, a green shoot).

He was knighted in 1897 and awarded the Order of Merit in 1910 for his contribution to scientific research.

Crookes was President of the Society for Psychical Research 1896 – 1899.