Thomson continued to investigate the cathode rays, and he calculated the velocity of the rays by balancing the opposing deflection caused by magnet and electric fields in a cathode ray tube. The idea of charge need not arise, in fact does not arise as long as we deal with the ether alone.” Thomson was starting to develop a clear mental picture of the nature of an electric charge, that it was related to the chemical nature of the atom.Ītoms are not indivisible, for negatively electrified particles can be torn from them by the action of electrical forces. He wrote: “…The relations between matter and electricity is indeed one of the most important problems in the whole range of physics…These relations I speak of are between charges of electricity and matter. By 1895, Thomson’s theory of discharge had evolved he maintained throughout that gaseous discharge was similar to electrolysis, in that both processes required chemical disassociation. Thomson was beginning to realize that the cathode rays were discrete charges rather than a mechanism for energy dissipation. Thomson wrote of gaseous discharge: “Preeminent for the beauty and variety of the experiments and for the importance of its results on electrical theories.”Īround 1890, Thomson’s research on gaseous discharges took a new direction with the announcement of the results of the German physicist Heinrich Hertz’s experiment demonstrating the existence of electromagnetic waves in 1888. The phenomenon has been known since the seventeenth century, and today it is the same effect we see in fluorescent light bulbs. As the electrical potential is increased across the electrons, the tube will begin to glow, or the glass tube will begin to fluoresce. Gaseous discharge is the phenomenon seen when a glass vessel (cathode tube) is filled with gas at low pressure and an electric potential is applied across the electrodes.
The phenomena of gas discharge had attracted much attention in the early 1880s due to the work of the British scientist William Crookes and the German physicist Eugen Goldstein. Thomson was initially interested in pursuing the theories of his predecessor at the Cavendish, James Maxwell. Now as the head of the Cavendish, he had a duty to experiment with the added luxury of being able to choose his own course of investigation. William Devonshire was the descendant of Henry Cavendish, the eccentric scientist who had been a pioneer of electrical experiments, discovered the composition of water, and measured the gravitational constant. This all changed in 1870, when the Chancellor of the University, William Cavendish, 7 th Duke of Devonshire, provided the money out of his own pocket to build a world class scientific research facility. As a result, the laboratories at Cambridge were behind the other universities in Britain. Even with his heavy teaching load, he didn’t ignore his research and started spending some time in the laboratories working with the equipment.Īt Cambridge University, the theoretical aspects of science had always been emphasized rather than the practical laboratory work. This required a lot of his time in teaching classes, a task he always said he enjoyed. In 1882, he was elected to an Assistant Lectureship in mathematics. Thomson’s fellowship thesis was never published however, he did publish two long papers in the Philosophical Transaction of the Royal Society, and in a book, published in 1888 and titled, Applications of Dynamics to Physics and Chemistry. During this time, he worked in several areas of mathematical physics, concentrating on expanding the work of James Clerk Maxwell in electromagnetics.
Thomson graduated second in his class in mathematics in 1880 and was awarded a fellowship to stay at Trinity for graduate work. He would remain at Trinity in some capacity for the remainder of his life. Wanting to continue his education in math and science, Thomson won a scholarship to Trinity College, part of Cambridge University, and began there in 1876. Cambridge University and the Cavendish Laboratory At Owens, he published his first scientific paper, “On Contact Electricity of Insulators," an experimental work elucidating a detail of James Clerk Maxwell’s electromagnetic theory. Since the family could no longer afford the cost of an engineering apprenticeship for young Thomson, he was forced to make his way with scholarships in the two areas in which he excelled: math and physics. J.J.’s younger brother, Fredrick, left school and got a job to help support the family. In 1873, two years into his education at Owens, Thomson’s father died, leaving the family in financial distress.