iraria.il vj 



YOL. XYIII. JULY, 1904. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWAED S. DANA. 



ASSOCIATE EDITORS 



Professors GEOKGE L. GOODALE, JOHN TEOWBEIDGE, 

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



Professors ADDISON E. VEEEILL, HOEACE L. WELLS, 

 L. V. PIESSON and H. E, GEEGOEY, of New Haven, 



Professor GEOEGE E. BAEKEE, of Philadelphia, 

 Professor HENEY S. WILLIAMS, of^bha&a^.^^ 

 Professor JOSEPH S. AMES, of Baltimore, 

 Mr. J. S. DILLEE, of Washington. 



FOURT H SERIES 

 VOL. XYIII— [WHOLE NUMBEK, CLXYI 



No. 103.— JULY, 1904. 



NEW HAVEN, CONNECTICUT. 

 1904 



CE TETTLE, MOREHOUSE & TAYLOR- CO., PRINTERS, 123 TEMPLE STREET. 



Published monthly. Six dollars per year, in advance. $6.40 to countries in the 

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