Walter Ritz as a theoretical physicist and his research on the theory of atomic spectra

An historical and methodological analysis is given of the scientific heritage of the remarkable Swiss theoretical physicist Walter Ritz (1878—1909) on the basis of a study of his complete works edited in 1911. The general characteristics of Ritz's works — including the papers on spectroscopy, the variational method, and electrodynamics — are discussed, and his fundamental research in the theory of atomic spectra is considered in detail. The elastic and the magnetic atomic models, proposed by Ritz to explain the spectral laws and based on a classical approach, are discussed. It is shown that the generalised Balmer and Rydberg formulas and the combination principle, which later became a basis for the formulation of Bohr's frequency condition, were obtained by Ritz as a result of mathematical deductions from his models and were not of semi-empirical character as is usually believed.