TBC
The arc length of an archimedean spiral: http://fiji.sc/downloads/snapshots/arc_length.pdf Number of turns: http://www.physicsforums.com/showthread.php?t=601610 Manca un po' di matematica.
Modified http://d3js.org/d3.v3.min.js to a secure url
https://d3js.org/d3.v3.min.js