Comparative tests of Illinois Central Railroad locomotives No. 920 and No. 940
An engineering thesis submitted at the University of Illinois in 1909 by Miles Otto Gibson and Frederick Ayres Lorenz, reporting comparative performance trials of two Illinois Central Railroad steam locomotives for faculty examiners and railway engineers. The plates are hand-drawn multicolour curves in red, blue, green and black inked over printed orange graph grids, with stepped speed profiles, oscillating traces and small handwritten numeric annotations along vertical axes.
