Abstract

I have noticed in several places the statements that Descartes calculated an enormous number of ray paths through a raindrop in explaining the rainbow^1,2. The origin of this belief is unclear. A possible source may be the comment by Taylor³ in his physics text that Descartes "…traced some ten thousand rays through a drop…" in order to find the cause of the bow. However, Boyer⁴ notes that Grau⁵ made such a claim in the 19th century. Because this mistaken belief seems widespread it seems worthwhile to point it out yet again.

© 1983 Optical Society of America