Answer:
J.J. Thomson
Explanation:
According to my book and wiki, Historically, the mass of the electron was determined directly from combining two measurements. The mass-to-charge ratio of the electron was first estimated by Arthur Schuster in 1890 by measuring the deflection of "cathode rays" due to a known magnetic field in a cathode ray tube. It was seven years later that J. J.
Please correct me if I'm wrong.
