Effectiveness of indirect illumination
A 1909 undergraduate engineering thesis on indirect illumination by Ross Harper Arnold and Homer Langdon Hadley, submitted at the University of Illinois and read by lighting engineers and faculty examiners. Its plates are hand-inked contour diagrams drawn on printed graph paper, each showing a square room plan, small circled lamp positions, concentric foot-candle curves and a lettered-and-numbered grid, with typewritten candle-power and wattage tables below; useful for grid-paper textures, technical contour shapes and typed tabular captions.
