At the Royal Institution in London, J. J. Thomson, the Cavendish Laboratory's leading physicist, delivered a seminal lecture that would ignite a profound scientific revolution. During his presentation, he discussed his investigations into cathode rays, a stream of charged particles that appeared when electricity was passed through gases at low pressure. Thomson's meticulous experiments led to the unexpected conclusion that these rays were composed of very small particles, which he named 'corpuscles', later known as electrons. He reported that these electrons were much smaller than atoms, with a mass about 1/1836 that of a hydrogen atom, or over 1,800 times smaller than a proton, fundamentally challenging the established view of atomic structure.Thomson's findings suggested that atoms were not indivisible, as previously thought, but were made up of these smaller subatomic particles. This groundbreaking revelation paved the way for the development of modern atomic theory. His experiments provided evidence contrary to Dalton's atomic theory, which viewed atoms as the smallest units of matter. Scientists worldwide were drawn to Thomson's conclusions, leading to further experimentation and collaborative endeavors in physics. His work laid the groundwork for later developments by scientists such as Ernest Rutherford and Niels Bohr, who would expand on the understanding of atomic structure and quantum theory in the 20th century.