cathode rays (a short history)
1855 Heinrich Geissler developed the first good vacuum tubes, these tubes, as modified by Sir William Crookes, could produce cathode rays.
1858 Julius Plücker showed that cathode rays bended under the influence of a magnet.
1865 Plücker proved that at lower pressure, the so-called Faraday dark space grows larger in the tube. He also found that there was an extended glow on the walls of the tube and that this glow might be affected by an magnetic field.
1869 J.W. Hittorf found that a solid object put in front of the cathode cut off the glow from the walls of the tube and presented that "rays" from the cathode travelled in straight lines.
1871 C.F. Varley was first to publish suggestion that cathode rays was composed of particles. Crookes meant that they are molecules that have picked up a negative charge from the cathode.
1874 George Johnstone Stoney estimated the charge of these particles to be about 10-20 coulomb, close to the precise value of 1.6021892 x 10-19 coulomb of the electron. He also proposed the name "electrine" for the unit of charge on a hydrogen ion. In 1891, he changed the name to "electron."
1876 Eugen Goldstein presented that the radiation emitted when an electric current is forced through the tube starts at the cathode and introduced the term cathode ray.
1881 Herman Ludwig von Helmholtz showed that the electrical charges in atoms amounted to integral multiple of a smallest unit of electricity.
1886 Eugen Goldstein observed in a cathode-ray tube an other radiation that travels in the opposite direction - away from the anode, later these will be found to be ions.
1892 Heinrich Hertz observed that the rays can penetrate thin foils of metal, and he arrived again at the incorrect conclusion that cathode rays might be some form of wave. Philipp von Lenard ssembled a cathode-ray tube with a thin aluminum window that allowed the rays to leave the tube, such the rays could be studied in the open air. He predicted that cathode rays would move with the velocity of light.
1894 J.J. Thomson published that he has measured the velocity of cathode rays which was much lower than that of light. (1.9 x 107 cm/s, as compared to the value 3.0 x 1010 cm/s for light.)