branch of study: optics
as used by: Isaac Newton, around 1670
In 1672, Isaac Newton published an article on the composition of the sun's light. He put forward the opinion, that the spectral colours were inherent properties of the white light. A key argument in Newton's argumentation was the so-called "experimentum crucis", which was supposed to show, that a second prism in the light's path would not divide the colours any further.
The experimentum crucis failed due to the fact, that unexpected optical effects could be seen in the second spectrum. For the act of scientific retracing, prisms of a contemporary quality were made so that the failure could be understood.