Scientific American, Vol. 21, No. 23 (December 1869)
An issue of the weekly New York technology and patent journal Scientific American, published by Munn & Co. in December 1869 for inventors, mechanics, and manufacturers. The plates are small wood engravings of patented devices—clamps, a rotating calculating dial, a hand-held blowpipe—drawn in line and crosshatch with cutaway sections, italic figure numbers, and letter keys tying parts to the text.
