VOL. XX\ T 11I. 



JULY, 1909. 



Established by BENJAMIN SIIXIMAN in 1818. 



THE 



i AMERICAN 



I JOURNAL OF SCIENCE. 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEORGE L. GOODALE, JOHN TROWBRIDGE, 

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



Professors ADDISON E. VEKKILL, HORACE L. WELLS, 

 L. V. PIRSSON and H. E. GREGORY, of New Haven, 



Professor GEORGE F. BACKER, of Philadelphia, 

 Professor HENRY S. WILLIAMS, of Ithaca, 

 Professor JOSEPH S. aMES, of Baltimore, 

 Mr. J. S. DILLEK, of Washington. 



FOUBTH SERIES 



VOL. XXVIII-[WHOIE NUMBER, CLXXVIII/] 



No. 163- JULY, 1909. 



NEW HAVLN, CONNECTICUT. 



• 1009. 



THE TUTTLE, MOREHOUSE & TAYLOR CO., PRINTERS, 123 TEMPLE STREET. 



*smm*mit m 



Published monthly. Six dolhrs per year, in advance. $6.40 to /^fctfes in the 

 stal Union ; $6.25 to Canada. Remittances should be made either m "money orders 

 mistered letters, or bank checks preferably on New York banks). JU I %' ^ Q(>9 



Sial Mus*>!V 



