Only when almost all the air has been removed to create a high vacuum – a state that would shatter ordinary glass vessels – can the rays travel the full length of the tube without bumping into air molecules. The quality of Everett’s glassblowing was absolutely crucial for the experiments to work.Ĭathode-rays are produced when an electric current is passed through a vacuum tube. Everett made all of Thomson’s apparatus, and was responsible for operating it – in fact, he generally forbade Thomson from touching anything delicate on the grounds that he was “exceptionally helpless with his hands”. Cambridge’s Cavendish Laboratory, where Thomson spent his scientific career, also has an original tube in its collection.Įach tube was custom-made by Thomson’s talented assistant, Ebenezer Everett, a self-taught glassblower. Using more than one cathode-ray tube in 1897 for his experiments, Thomson managed to identify a particle 1,000 times smaller than the then known smallest piece of matter: a hydrogen atom. I had read lots about Thomson’s famous experiments on the electron – the first subatomic particle to be discovered – but to actually see and touch his apparatus myself, to notice the blackened glass and the tube’s minute features that are omitted in books, brought the object to life. Holding the delicate glass cathode-ray tube in my hands, once used by the great physicist JJ Thomson, was an incredible treat, and an experience I will never forget. Rupert Cole celebrates JJ Thomson’s birthday with a look at one of the star objects in our Collider exhibition. Rupert Cole celebrates JJ Thomson's birthday with a look at one of the star objects in our Collider exhibition.
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