VOL. XXXIX. JANUARY, 1915 



Established by BENJAMIN SIILIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF -SCIENCE. 



Editor: EDWAKD S. DANA. 



ASSOCIATE EDITORS 



Professors GEOKGE L. GOODALE, JOHN TROWBRIDGE, 

 W. G. FARLOW and WM. M. DAVIS, of Cambridge, 



Professors ADDISON E. VERRILL, HORACE L. WELLS, 



LOUIS V. PIRSSON, HERBERT E. GREGORY 



and HORACE S. UHLER, of New Haven, 



Professor HENRY S. WILLIAMS, of Ithaca, 



Professor JOSEPH S. AMES, of Baltimore, 



Mr. J. S. DILLER, of Washington. 



FOURTH SERIES 

 VOL. XXXIX-[WHOLE NUMBER, CLXXXIX]. 

 No. 229— JANUARY, 1915. 



NEW HAVEN, CONNECTICUT. 



1915. 



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