First lessons in metal-working
A late nineteenth-century instruction manual by Alfred G. Compton, published in New York in 1890, teaching beginners the basic techniques of metalworking. The four pictures are cutaway line diagrams of metal pieces in cross-section: a bar lapped and joined to a hatched block, a bent strip clamped against a stepped block, and a tool pressing a curved sheet against a corner. A designer could take from them the clean hatched-section convention and the clear, labelled way of showing how parts fit together.
