Wormharmonie
A Dutch treatise on form harmony by J. H. de Groot, published in Amsterdam by W. J. Ahrend in 1912 for architects, designers and drawing teachers working from geometric proportion systems. The plates are thin-line geometric constructions—circles, ellipses, tangents, bisectors and lettered points on ruled baselines—printed in black on cream, offering ready compass-and-straightedge diagrams, proportion grids and construction armatures for layout work.
