The Rydberg formula on the wavelengths of a spectral line in chemical elements was first stated empirically in 1888 by Johannes Rydberg. A theoretical explanation of the formula wouldn't arive until Niels Bohr's quantum-mechanical model of the atom in 1913. A quick search tells me that Rydberg became severely ill precisely in 1913, only to pass away six years later. It seems not unlikely that Rydberg learned of Bohr's explanation. Are there any accounts of this?