Geometrical mosaic



Our holiday cottage in Lindos has this wonderful mosaic in the floor. It's made from black and white pebbles each about 2cm in diameter which gently massage your feet as you walk over them. In the doorway the same pebbles write out the date 1908.

Looking at a design like this I can't help trying to reverse engineer it.  The first thing you notice is that the edges of the white quadrilaterals share a straight line with the edges of the black ones.  In fact all the shapes other than the concentric circles are formed by intersecting chords of the outer circle.

The next observation is that these chords come in parallel pairs which are tangent to the inner circle on opposite sides.  These observations are enough to generate a recipe:


  1. Draw the outer circle
  2. Mark every 20 degrees to split into 18 equal parts
  3. Draw a chord between point n and point n+8
  4. Repeat for n = 0...8
  5. Draw the inner circle
I had a go at this using Handwrite Pro on my phone. I ended up using a slightly different recipe because it can only draw horizontal and vertical lines (unless you use freehand) and can only rotate images through multiples of 22.5 degrees:


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