1. Your author had to perform this experiment as a graduate students in physics. I had to leave my wristwatch outside the room lest it be damaged by the field of the magnet. I sat in the dark beside a large electromagnet, a Bunsen burner glaring yellow from salt held in its flame, while peering through a small telescope at the sodium D-lines. I switched on the field and it was exciting to see the sodium lines change their appearance. Little did I know that this same experiment, shifted to an astronomical context, would some day determine my life as an astronomer.
2. Zeeman, P. (1897) “On the influence of magnetism on the nature of light emitted by a substance.” Astrophys. J., 5: 332.
3. Ibid.
4. Michelson, A.A. (1898) “Radiation in a magnetic field.” Astrophys. J., 7: 131.
5. Lorentz, H.A. (1899) “Considerations concerning the influence of a magnetic field on the radiation of light.” Astrophys. J., 9: 37.