Royal Institution lecture programme, 1897. Pamphlet featuring a lecture by Sir Joseph J Thomson (1856-1940) on cathode rays. After graduating from Trinity College, Cambridge, Thomson continued to work at Cambridge University and in 1896 began experiments on cathode rays. In Britain physicists argued these rays were particles, but German physicists maintained they were a type of electromagnetic radiation. Thomson showed that cathode rays were particles with a negative charge and much smaller than an atom. These particles were later renamed electrons.
© Science Museum / Science & Society Picture Library