1 0 8 D O C U M E N T 9 4 N O V E M B E R 1 9 2 7 With increasing n (I was able to reach a minimum wavelength of 24 cm), the brightening of the plate increases, and it apparently tends toward a lim- iting value, which is, however, not yet reached. The brightening is great- er at the lower vapor temperature of 280°, corresponding to the narrower line width than at 480°C. Unfortunately, the degree of brightening can be measured only relatively, so that the absolute size of the splitting of  cannot be quoted. For a more quantitative measurement, one would have to know: the structure of the emission line, the shape of the absorption curve in A & of the frequency band, & the harmonics of the Hertzian oscillators. Nevertheless, I believe that what I intended to demonstrate has been observed: the superposition of & n.— Since this experiment is in principle related to the canal ray lattice experiment,[4] an objectification of the latter experiment has been achieved, which, although I am confident that my earlier, subjective results are cor- rect, will not be unimportant for many.— Permit me to send you as an enclosure a print of the photos showing the brightening. One can clearly see that with increas- ing n, the brightening also increases. Respectfully yours, E. Rupp