1. The " Quarter-Circle" approximation of the equiangular spiral k = Phi ⁴
2. The equiangular spiral k = Phi ⁴ (Growth 6.854 : 1, 1.618034/quadrant)
3. For an associated sea shell spiral, see Animation Two (Haliotis Parva)
For the " Root Five rectangle ", R.C. Archibald's: Notes on the Logarithmic Spiral, Golden Section and the Fibonacci Series, see Jay Hambidge, Dynamic Symmetry 1920:16-18, 146-147. Return to Spira Solaris and the Pheidian Planorbidae