VOL. II JULY, 1921 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors WILLIAM M. DAVIS and REGINALD A. DALY, 



OF Cambridge, 



Professors HORACE L. WELLS, CHARLES SCHUCHERT, 



HERBERT L. GREGORY, WESLEY R. COE and 



FREDERICK E. BEACH, of New Haven, 



Professor EDWARD W. BERRY, of Baltimore, 

 Drs. FREDERICK L. RANSOME and WILLIAM BDWIE, 



OF Washington . -• . . yv-s*^ ^ ' ' "^ " '" ^ Hr 



FIFTH SERIES 



VOL. II— [WHOLE NUMBER, OGIIl^-; 

 No. 7— JULY, 1921. 



NEW HAVEN, CONNECTICUT. 



19 21. 



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