VOL. X. JULY,- 1900. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWARD S. DANA. 



ASSOCIATE EDITORS 



Professors GEO. L. GOODALE, JOHN TROWBRIDGE, 

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



Professors A. E. VERRILL, HENRY S. WILLIAMS, and 

 L. V. PIRSSON, of New Haven, 



Professor GEORGE F. BARKER, of Philadelphia, 



Professor H. A. ROWLAND, of Baltimore, 



Mr. J. S. DILLER, of Washington. 



FOURTH SERIES. 



YOL. X— [WHOLE NUMBER, CLX.] 



No. 55.— JUL^f 1900. 



\ JOL 3 1900J 



phonal Mujg^ 



"' '■■■ -. ■ 



NEW HAVEN, CONNECTICUT. 

 1900. 



THE TUTTLE, MOREHOUSE & TAYLOR CO., PRINTERS, 125 TEMPLE STREET. 



Published monthly. Six dollars per year (postage prepaid). $6.40 to 

 foreign subscribers of countries in the Postal Union. Remittances should 

 be made either by money orders, registered letters, or bank checks. 



