  According to Weyl (1923c) this relationship holds in arbitrary  spacetimes and for arbitrary motions of source and observer. Weyl  (1923b, Anhang III) then applied this relationship to de Sitter’s  world and showed, to lowest order, that the redshift is linear  in distance; that is, Weyl theoretically derived, what was later called Hubble’s redshift law. Using Slipher’s  redshift data Weyl estimated a Hubble constant six years  prior to Hubble. Weyl (1923b, Anhang III) remarks: 