Charles Bruce: More Electrical Properties
Charles Bruce extended Birkeland, from the idea that EM could explain a few of the observations from the Sun, to explaining a lot of observations on a lot of stars.1 He never debated the solar energy source — he was just addressing the nature of the observations, and maintaining that they were electrical in nature. (See this for more info.)
Charles Bruce (1902~1979).
References
1. Bruce, C. E. (1944): A New Approach in Astrophysics and Cosmogony. London and Woking: Unwin Brothers Limited ⇧