Worm gearing
A 1916 McGraw-Hill technical manual by Hugh Kerr Thomas on the design and cutting of worm gearing, written for mechanical engineers and machine-shop draughtsmen. The plates are line diagrams: unrolled helix triangles, thread profiles in section with hatched flanks, shafts and tooth arcs, all labelled with Greek letters, dimension arrows and formulae worth lifting as geometric ornament.
