One copy, six months, postage included 1 60
Clubs.--One extra copy of THE SCIENTIFIC AMERICAN will be supplied
gratis for every club of five subscribers at $3.20 each: additional
copies at same proportionate rate. Postage prepaid.
Scientific American, Volume XLIII., No. 25, December 18, 1880 A Weekly Journal of Practical Information, Art, Science, Mechanics, Chemistry, and Manufactures. · 第 11 / 165 题