Belt conveyors and belt elevators
An engineering handbook by Frederic V. Hetzel on belt conveyors and elevators, published in New York by John Wiley and Sons in 1922 for mill and plant engineers. Line diagrams show pulleys, chutes, idler frames, take-up mechanisms and belt sag geometry, with stippled bulk material and dimension callouts — usable as technical linework, labelled schematics and catenary curve motifs.
