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From Timothy Campbell

Your Invention column describes a patent for marking a ball with a pattern of 55 dots in five colours, which will present a unique appearance at every possible angle (8 May, p 23). This sounded unnecessarily complex to me, so I pulled out an orange and marked the surface into eight “triangular” sections, or octants. I then painted it red, yellow, green and blue.

It doesn’t matter which way you turn this ball, you always get a unique view. Am I missing something important about that bespeckled ball mentioned in your column? Or should I be contacting a patent attorney, since my ball apparently does what theirs does, and it is much prettier (see ).

The editor writes:

• To be fair to the inventors, they do say in their long and complicated patent that solutions with fewer markings are possible and the invention also applies to non-spherical balls with irregular shapes.

Toronto, Canada