## tessellation

**Lewis Dartnell**explains, our brains have evolved to take pleasure in rhythm, structure and pattern. Since these topics are fundamentally mathematical, it should be no surprise that mathematical methods can illuminate our aesthetic sense.

**Alison Boyle**tells

*Plus*about her work creating up-to-the-minute news exhibits at the Science Museum in London.

*Plus*talks to

**Sir Roger Penrose**about all this and more.

**Alison Boyle**investigates aperiodic tilings, which have had unexpected applications in describing new crystal structures.

**Bill Casselman**writes about the intriguing amateur mathematician Henry Perigal, who took his elegant proof of Pythagoras' Theorem literally to his grave - by having it carved on his tombstone.