 where the integral is taken over one period of the electron orbit, and \(p_{\theta}\) is the angular momentum, \(\theta\) is the angle in the plane of the electron orbit, and \(n\) is the quantum number.[2] As Max Jammer summarizes, applying the old quantum theory consists of essentially three steps: “first, the application of classical mechanics for the determination of the possible motions of the system; second, the imposition of certain quantum conditions for the selection of the actual or allowed motions; and third, the treatment of the radiative processes as transitions between allowed motions subject to the Bohr frequency formula” (Jammer 1966, p. 90). The old quantum theory was a blending of classical and quantum ideas: while it is assumed that the motion of an electron within a particular stationary state can still be described on the basis of the classical theory, the radiation given off in a transition between stationary states (the “quantum jumps”) cannot.