1. Transmitting Knowledge across Divides
2. Sellmeier did not consider frictional forces. Other physicists took them into account, but Sellmeier's formula continued to be a good approximation in most cases
3. By resonance model, I mean the very general notion of resonance process taking place between light and matter, and the mathematical formulation of an abrupt behavior of n at the resonance frequencies. So defined, the resonance model was closely associated to the experimental pattern of dispersion with discontinuities at the characteristic frequencies of matter. Ever since the early 1870s, this model was instantiated by different dispersion theories that relied on different, specific theories of light and matter