and
, connected in a very simple manner with the kinematic properties of the orbit. For brevity I shall only mention that while the quantum number
is connected with the value of the constant angular momentum of the electron about the centre in the simple manner previously indicated, the determination of the principal quantum number
requires an investigation of the whole course of the orbit and for an arbitrary central orbit will not be related in a simple way to the dimensions of the rotating periodic orbit if this deviates essentially from a Keplerian ellipse.
Fig. 2.
These results are represented in [Fig. 2] which is a reproduction of an illustration I have used on a previous occasion (see Essay II, [p. 30]), and which gives a survey of the origin of the sodium spectrum. The black dots represent the stationary states corresponding to the various series of spectral terms, shown on the right by the letters