Newall, H. F · London : Society for Promoting Christian Knowledge · leaf 48
Fig. 23. Fig. 24. transparency. The scale is fixed at the principalfocus of the lens, that is, at such a distance from thelens that the rays of light proceeding from eachpoint of the scale pass out of the lens in parallelbeams. These fall upon the polished surface of theprism (the second face), and…
Spectroscope · Spectrum analysis
Internet Archive · Wellesley College Library · Public Domain Mark 1.0. Free to use for anything.
