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In studying Dawson's work Ploog had to understand basic concepts and practices of civil engineering, including two methods early 20th-century engineers used to construct accurate blueprints -- descriptive geometry, which uses drawings, and analytical geometry, which uses mathematical formulas. In "Prognostic," Dawson used both techniques, as evidenced by the mathematical symbol of a partial derivative (lower left) and a drawing from his engineering textbook "Stereotomy: Problems in Stone Cutting," written by S. Edward Warren in 1884.

IMAGE: Penn State