The design, construction and test of a direct reading engine indicator
An undergraduate engineering thesis by Alexander McJunkin Tower and Humphreys Oliver Siegmund, submitted at the University of Illinois in 1917, documenting an instrument built to trace pressure curves inside internal combustion engines. The plates are oscillograph photographs — thin white traces, spikes and smooth waves on dense black grounds — alongside line diagrams; useful as high-contrast waveform and graph material.
