Automobile mufflers
An engineering thesis on automobile mufflers written by John Isaac Edwards and Reginald Ellis Wells at the University of Illinois in 1906, prepared for faculty examiners and readers in early motor-vehicle mechanics. The plates are longitudinal sections of cylindrical exhaust chambers in hatched line engraving and halftone, with dimension marks and arrows tracing gas flow, offering designers cutaway silhouettes, diagonal hatch fills, and annotated flow-arrow diagrams.
