Eddington’s theory of stars was a great success. To recall, this theory was predicated on the assumption that stars are globes of ideal gas in radiative equilibrium. The spectacular agreement between many of the predictions of this theory and observations lulled astronomers into thinking that that last word on the subject had been said. This feeling was shattered in 1924 when the American astronomer Walter Adams made a remarkable discovery regarding the companion of Sirius. But we are jumping the story! Let us go back and trace the history of this fascinating discovery.