Changes in the wave-frequencies of the lines of emission spectra of elements
A physics dissertation by William Jackson Humphreys, published by the University of Chicago in 1897, reporting laboratory measurements of how pressure shifts the emission lines of elements. Plates pair photographed spectrograms—dense vertical line bands with inked wavelength annotations—with thin-line engineering drawings of the pressure vessel and a zigzag chart plotting line shift against atomic weight, useful as ruled-stripe texture and instrument diagram.
