century, it was identified with the Geschwindigkeitsvectoren (velocity vectors) by Hermann Minkowski in his 1907 Göttingen lecture 'The Relativity Principle'. Scott Walter, in his 1999 paper "The Non-Euclidean Style of Minkowskian Relativity" recalls Minkowski's awareness, but traces the lineage of the model to Hermann Helmholtz rather than Weierstrass and Killing. In the early years of relativity the hyperboloid model was used by Vladimir Varićak to explain the physics of velocity. In his speech to the German mathematical union in 1912 he referred to Weierstrass coordinates. See also Poincaré disk model Hyperbolic quaternions Notes and references , Chapter 3 Miles Reid & Balázs Szendröi (2005) Geometry and Topology, Figure 3.10, p 45, Cambridge University Press, , . Multi-dimensional geometry Hyperbolic geometry Minkowski spacetime