《Scientific American Supplement, No. 288, July 9, 1881》 - 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 Seyfferth's Pyrometer, Organic Matter in Sea-Water, On the Composition of Elephants' Milk, and Economy of the Electric Light. - Summary by Larry Wilson