Light and color comparison for incandescent lamps
A 1907 University of Illinois engineering thesis by Roy Newton Fargo comparing the light and color output of carbon, metallized, and tantalum incandescent filament lamps, submitted for academic examination and signed by instructors. The plates are hand-drawn ink curves on printed graph paper, with hand-lettered axis labels reading spectrum positions R O G B V and ratios of intensity, plus a page of pen signatures; usable as ruled grid textures, vintage technical lettering, and plotted line diagrams.
