General problems of shades and shadows
A descriptive-geometry textbook by Samuel Edward Warren, published by John Wiley & Sons in New York in 1895 for engineering and architecture students learning to construct shades and shadows. The plates are lithographed line diagrams: circles, ellipses, cones and mouldings crossed by ray lines and lettered points, with shadow areas filled in flat grey, usable as geometric pattern and technical-drawing texture.
