Space and geometry in the light of physiological, psychological and physical inquiry
Three essays by the Austrian physicist Ernst Mach on the origins of geometrical ideas, translated by Thomas J. McCormack and published in Chicago by Open Court in 1906 for philosophers and students of mathematics and psychology. The figures are spare line diagrams on cream paper: dissected squares proving the Pythagorean theorem, intersecting lines with Greek angle labels, and inscribed triangles in semicircles, useful as plain geometric marks, numbered-shape puzzles, and lettered angle notation.
