The rotation of the polarization plane is extraordinarily small in all gases, thus also in sodium vapour.
Pieter ZeemanMoreover, photography has made it possible to fix these images and now provides us with a permanent record of each observed spectrum, which can be measured out at any time.
Pieter ZeemanOn the basis of Lorentz's theory, if we limit ourselves to a single spectral line, it suffices to assume that each atom (or molecule) contains a single moving electron.
Pieter ZeemanI count myself fortunate to be able to contribute to this work; and the great interest which the Royal Swedish Academy of Sciences has shown in my work and the recognition that it has paid to my past successes, convince me that I am not on the wrong track.
Pieter Zeeman