Further Determinations of the Curvature Radius of Space-Time

IN continuation of my letter of January 1 on this subject, published in NATURE of March 8, p. 350, I should like to add, in the first place, two more items to the list of eight R-values then determined from seven globular clusters and the Lesser Magellanic Cloud. According to R. E. Wilson (Publs. of the Lick Observatory, 13, part 5, 1918, p. 187) the Greater Magellanic Cloud shows a spectrum shift this being the mean of seventeen but slightly different effects for as many nebulæ distributed over the area of the cloud. The distance of this cloud is estimated by Shapley (Astrophys. Journ. 49, 1919, p. 322) at 61,000 light-years or astronomical units.