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Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



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. VERRILL, HORACE L. WELLS, 

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



Professor GEORGE F. BARKER, of Philadelphia, 

 Professor HENRY S. WILLIAMS, of Ithaca, 

 Professor JOSEPH S. AMES, of Baltimore, 

 Mr. J. S. DILLER, of Washington. 



FOURTH SERIES 

 YOL. XXII— [WHOLE NUMBER, CLXXIL] 



No. 130— OCTOBER, 1906. 



NEW HAYEN, CONNECT! 



1906 



THE TUTTLE, MOREHOUSE & TAYLOR CO., PRINTERS, 



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

 Postal Union. Remittances should be made either by money orders, registered 

 letters, or bank checks (preferably on New York banks). 



