《Scientific American Supplement, No. 446, July 19, 1884》 - 免费有声读物

The Scientific American may be the oldest continuously published periodical in the United States, havinge launched its first publication in 1845. It has been a mainstay of popular science with in depth articles across a broad spectrum of scientific fields. In this supplement are short articles ranging through such topics as Pneumatic Malting, Improved Hay-Rope Machine, Automatic Fast Speed Telegraphy, and Tin in Canned Foods Our Servants, The Microbes - Summary by Larry Wilson