Page:Elektrische und Optische Erscheinungen (Lorentz) 090.jpg

 that, when we are dealing with sun rays, we can neglect the velocity component $$\mathfrak{p}_{r}$$, on which the variation of the oscillation period depends (§ 37). Experiments with these rays must have the result, as if the earth were at rest, and the sun were in a direction changed by aberration, and would emanate types of light of the same oscillation period, as in reality

From that it immediately follows, that (as regards a certain line of during a refraction in a prism, or the diffraction through a lattice) we don't register any influence of Earth's motion, thus it cannot make any difference, whether the direction of light (that falls upon the prism of the lattices) would form this or that angle with the translation of earth. As regards the lattice-spectra, this result was confirmed by the careful experiments of. This physicist has additionally demonstrated by certain experiments, that as regards the mentioned spectra, the deflection for a certain line fully agrees with the deflection for the corresponding rays of a terrestrial light source.

Moving light sources.
§ 63. Above, in § 61, the celestial body was assumed to be at rest. Yet also for a moving body we arrive at a simple result. We already know (§ 36), that the perpendicular to the waves arriving at Earth, is directed to location P, where the light source