..., as g ( t ⃗ , t ⃗ p ) = − sinh α we find the corresponding Eular-Savary formula as 29 ( coth θ ′ − coth θ ) sinh α = Ψ σ p For all mutual point couples X , X ′ we give a meaning for Ψ ∕ σ p , which is the left-hand side...