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.
Remit by postal order. Address
MUNN & CO., 37 Park Row, New York.
-->To Advertisers.--The regular circulation of the SCIENTIFIC
AMERICAN is now FIFTY THOUSAND COPIES weekly. For 1880 the publishers
anticipate a still larger circulation.