Charles Thomson Rees Wilson was born on 14 February 1869 at the farmhouse of Crosshouse in the Pentland Hills. Following the death of his father four years later, the family moved to Manchester where Wilson later attended Owens College. There he studied biology with the intention of pursuing a career in medicine. Upon graduating he obtained an entrance scholarship to Sidney Sussex College, Cambridge, although he had in fact applied for a scholarship at Christ's College. Wilson graduated with distinction in 1892 and after a brief spell teaching in a Midlands grammar school, he returned to the Cavendish Laboratory, Cambridge, becoming a Clerk Maxwell Scholar in 1895.
Following observations made in 1894 at the meteorological observatory in the summit of Ben Nevis, he began experimenting to produce clouds artificially. In 1896 he used an X-ray tube developed by Everrett in the Cavendish Laboratory to show conclusively the condensation occurring in dust-free air sufficiently expanded was the result of charged atoms, later called ions. He considered that it should be possible to reveal the tracks of ionising particles and after years of experimental work he produced in 1911 the cloud chamber, described by Lord Rutherford as "the most original apparatus in the whole history of physics". In this instrument the tracking of atoms, or sub-atomic particles, were shown as trails of tiny water drops. The pictures he produced using the cloud chamber were of the highest quality and the cloud chamber itself went on to play a key role in the development of nuclear physics.
Following his discovery during early cloud chamber experiments that ions were continually being produced in the atmosphere, Wilson started research into atmospheric electricity. His interest was further stimulated by an experience on the summit of Ben Nevis when the sensation of his hair standing on end gave him warning of an imminent lightening stroke. This alerted his mind to the magnitude of electric fields within thunderclouds and the suddenness with which they changed. Wilson developed several types of electrometers for measuring the surface density of the earth's charge and electric field and field changes which took place during thunderstorms. As a result of his experiments in this area, he developed his theory of the mechanism of the generation of electrical charge in a thunderstorm. His last paper on the subject was published in the Proceedings of the Royal Society in 1956 . In 1900 Wilson was an elected member of the Royal Society and a Fellow of his College. The following year he became a lecturer and in 1925 became Vacksonian Professor of Natural Philosophy. During the course of his career, many honours were conferred on Professor Wilson by Universities and scientific societies, including the Nobel Prize for Physics, which was awarded in 1927 in conjunction with A H Compton. In 1956 he was made a Companion of Honour following his retirement. Professor Wilson died on 15 November 1959 in the village of Carlops in the Pentlands, close to his birthplace.
Sources: Biographical notes from the introduction to the collection.