Assertion: color's wavelength | /r/HasProperty | difficult to reproduce
Facets:
value: in 1931
type: TEMPORAL
Source sentences:
text: The 700 nm wavelength, which in 1931 was difficult to reproduce as a monochromatic beam, was chosen because the eye's perception of color is rather unchanging at this wavelength, and therefore small errors in wavelength of this primary would have little effect on the results.