The von Nardroff Color Mixing Apparatus
Ernest von Nardroff gave his name to the color mixing apparatus shown in Fig. 1. The basic idea behind this demonstration is to produce three beams of colored light that may be projected onto a white surface. If beams of red, blue, and green are overlapped to produce a figure like a three leaf clover or a Venn diagram, the region of complete overlap will appear white, and the three regions of overlap of two colors produce the three false primaries: yellow, magenta, and cyan. A straightforward technique is to use three slide projectors, each with a colored filter. Von Nardroff's apparatus, displayed at the educational exhibit of Erasmus Hall High School at the Louisiana Purchase Exposition in St. Louis in 1904, permits the use of only one projector.
“The von Nardroff Color Mixing Apparatus”, The Physics Teacher, 43, 602), 2006)
The Physics Teacher