Scientific American, Vol. 21, No. 23 (1869)
This is a weekly American science and invention periodical, Scientific American volume 21 number 23 from 1869, printed for a general readership of engineers, mechanics and inventors. Its pictures are black-and-white wood engravings of mechanical devices with labelled parts, such as a circular calculating dial with addition, subtraction, multiplication and division scales, a clamp-and-rod fitting, and a bearing bracket bolted under a timber beam, offering a designer clear, diagrammatic technical line drawing and lettering references.
