The path of the rays could be inferred by the positon of the fluorescence on a square arceen in the bell jar. Thomson repeated the experiment, changing the material of the anode and the type of gas in the bell jar each time. However, he found that the deflection of the rays remained the same in each experiment. He suggested that the cathode rays had the same composition, regardless of where they came from. Thomson went on to perform three experiments that led to the discovery of the electron