Scientific American, Vol. 24, No. 19 (1871)
A weekly American science and invention periodical from 1871, volume 24, issue 19, aimed at engineers, mechanics and general readers of the period. Its pictures are plain line engravings of steam engine parts such as valve gear, a slide valve, a steam separator and a heat exchanger, drawn in cutaway and section with lettered reference marks. A designer could take from them the clean hatching and cross-section conventions of 19th-century technical drawing.
