Abstract
Near the end of the 19th century the Swede Johannes Rydberg gave science the physical constant now identified by his name. Searching for patterns among wavelength-dispersed atomic spectra, early spectroscopists found empirical formulae that gave the inverse wavelength of some spectral lines. For the simplest atom, hydrogen, the formula involves differences of the inverse square of integers and an empirical constant of proportionality, R, now known as the Rydberg constant.