Benham’s top
A black and white disc that spins into colour.
How this site works. Every fact is in our own words and linked to its source, beside it. Where good sources disagree, we show each version in a “Sources differ” box. Every picture is our own drawing: we don’t copy the famous originals, we make our own versions of the idea.
The top
Benham’s top is a black and white disc that, when it spins, shows faint colours. Michael Bach
Spin it the other way and the colours swap places. Michael Bach
Take a photo of it spinning and the colours are not there. Michael Bach
Who found it?
Prévost saw colours ‘like a heavenly light’ on his fingers when he waved his hands about in the cloisters. Michael Bach
The effect was forgotten and rediscovered no fewer than twelve times. Michael Bach
Who was first? Sources differ
- The psychologist Richard Gregory traced it back further, to a French monk, Benedict Prévost, in 1826. Michael Bach
- Bach says Gustav Fechner was the first to describe the effect, in 1838. Michael Bach
- In 1894 the toy maker Charles E. Benham sold his disc as an ‘Artificial Spectrum Top’. Michael Bach
Prévost saw coloured flicker in 1826, Fechner described it in 1838, and Benham turned it into a toy in 1894, which is why the top carries his name.
Why?
Nobody knows for certain why the colours appear. Michael Bach
Our view: a toy that makes colours out of black and white, and still puzzles scientists, is the best value toy ever sold.
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