Woldemar Voigt

“ If this is the case, then they differ only by their position against the coordinate axes. By appropriate use of the arbitrary constants and the functions U, V, W we can obtain vivid special cases. By coordinate transformation we are lead to a (at least formally) general case, in which the shift of the surface is not parallel to the A-axis parallel, but directed in an arbitrary way. ”

“ If the illuminating surface is a very small [AU 3] sphere of radius R, which oscillates according to the law for the rotation angle
around the X-axis, then, at the distance from the center of the sphere, the propagated rotations ψ are given by [2] [AU 4]
where
is set. ”

“ If, besides the illuminating surface, the observer is also in motion, such as with the constant velocity κ' in a direction given by the direction cosines α', β ', γ', then the displacements u, v, w,, which are only related to a coordinate system X', Y', Z' moving with the observer, i.e., we must replace in (12) or (13) by , by , by . ”