Page:Elektrische und Optische Erscheinungen (Lorentz) 119.jpg

more or less from this law; but we already know, that $\sigma$ is changing with the duration of oscillation, and j probably might depend on it as well.

The translation has two influences by our equation. First, it changes the already existing rotation in the ratio

$1+{\frac {W{\mathfrak {p}}_{x}}{V^{2}}}$,

(117)

and furthermore it additionally causes a rotation.

${\frac {2\pi }{\sigma ^{2}}}n'^{2}W{\mathfrak {p}}_{x}k$.

(118)

The theory cannot give a relation between this value and (116); probably such a relation doesn't exist at all, and cases could exist, in which j is very small, while k nevertheless has a noticeable value.

By the way, it is probably not required to be remarked, that the phenomena represented by (118) are similar to the polarization in so far, as it also only arises by an exterior influence, namely by the translation, and most strongly emerges, when this influence has the direction of the light rays.

§ 88. Experiments on the rotation of the polarization plane at different orientation, as far as I know, were only undertaken by Mascart^[1] He was unable to conclude a change of rotation with respect to quartz, when the light rays have, on one hand, the direction of Earth's motion, and on the other hand, the opposite direction. For the observation it had to be concluded, that the change in any case didn't amount the 20000th part of the rotation, and as regards a certain direction of the light rays, the rotation was altered by Earth's motion by less than 1/40000.

Due to the lack of a theory applicable for anisotropic bodies, we maybe also apply the above reported formulas to quartz. Now, since the refractive index is 1,55, and ${\mathfrak {p}}_{x}/V=1/10000$, then the value of the second member in (117) becomes

1. Mascart. Ann. de l'école normale, 2e sér., T. 1, pp. 210—214, 1872.