THE JOURNAL OF THE FRANKLIN INSTITUTE DEVOTED TO SCIENCE AND THE MECHANIC ARTS, PUBLISHED BY THE INSTITUTE, Under the Direction of the Committee on Publication. Vol. CXII.-Nos. 667–672. THIRD SERIES. VOL. LXXXII.-JULY TO DECEMBER, 1881. PHILADELPHIA: FRANKLIN INSTITUTE, NO. 15 SOUTH SEVENTH STREET. 1881. |