# Is this a logarithmic spiral?

I'm trying to draw a logarithmic spiral by hand (actually I need to use a plotter to cut a spiral on wood, but that is another story) and I saw this method:

http://www.wikihow.com/Draw-A-Perfect-Spiral

it seems to me like a log spiral, because, if precisely done, the distance to the center is shortened geometrically.

Let me know if I'm correct!.

Thanks!.

• I don't know of an easy mechanical way to draw a logarithmic spiral. I would just calculate and plot points, either on graph paper or in some program. Excel will plot a scatter plot, but it is hard to maintain vertical vs horizontal scale. – Ross Millikan Apr 2 '14 at 22:34

• I don't think you'll have a tidy way to do this "mechanically". A logarithmic (equiangular) spiral is self-similar: for any choice of points one "turn" (2 $\pi$ radians) apart in angle, the arclength must increase by a constant factor. It would be pretty tricky to "pay out" the right amount of string from the pencil everywhere along the path, since the amount of string would have to grow (or decrease, if you're "winding in" toward the limit point) "geometrically". [This is vaguely related to why Jacob Bernoulli got the wrong spiral engraved on his tombstone...] – colormegone Apr 2 '14 at 23:46