Willem de Sitter

“ P. Guthnick [1] and E. Freundlich [2] have brought forward the hypothesis that the velocity of light might depend on the velocity of the source in a manner differing from the simple addition postulated by the theory of Ritz. ”

“ The smallest values, of course, are found from the stars having the smallest parallaxes. Unfortunately the parallax of most spectroscopic doubles is still unknown, and it is thus impossible to give numerical values. We can however assume as certain that for the majority of these stars a value would be found which is still smaller than that given above.
Postscript. During the discussions at the meeting the remark was made (by Prof. Korteweg) that the star β Aurigae might have a true excentricity of such amount as exactly to cancel the spurious excentricity produced by the motion. ”

“ Thus if we knew only this one star, we should have to adopt as upper limit for this value 0.12. There are however a considerable number of stars with large values of u0, whose observed excentricity is very small or zero. Several of these certainly have very small parallaxes. It would evidently be absurd to assume that all of these possessed exactly that true excentricity and position of the periastron which would cancel the apparent excentricity for an observer on our earth. ”