# Mechanism for Drawing a Logarithmic Spiral

Mechanism for Drawing a Logarithmic Spiral

This Demonstration shows a mechanism for drawing a logarithmic spiral . A pivot point holds a rod with a sharp wheel at the far end. The axis of the wheel is at an angle to the rod; is chosen such that . As the wheel digs into the plane, it gradually pulls away from the pivot point and traces the spiral.

ρ=a

θ

μ

μ

tan(μ)=ln(a)