The American Journal of Science 



Established by Benjamin Silliman in 1818. 



THE LEADING SCIENTIFIC JOURNAL IN THE UNITED STATES. 



Devoted to the Physical and Natural Sciences, with special refer- 

 ence to Physics and Chemistry on the one hand, and to Geology and 

 Mineralogy on the other. 



Editor: Edward S. Dana. 



Associate Editors : Professor George L. Goodale, John Trowbridge, 

 and Wm. M. Davis, of Cambridge ; Professors A. E. Verrill, H. L. 

 Wells, C. Schuchert, L. V. Pirsson, H. E. Gregory, and H. S. Uhler, 

 of New Haven ; Professor Joseph S. Ames, of Baltimore ; Mr. J. S. 

 Diller, of Washington. 



Two volumes annually, in MONTHLY NUMBERS of about 80 pages each. 



This Journal ended its first series of 50 volumes as a quarterly in 1845; its 

 second series of 50 volumes as a two-monthly in 1870; its third series as a 

 monthly ended December, 1895. A Fourth Series commenced in 1896. 



Contributors are requested to revise their manuscript with special care with 

 reference to the use of the linotype machine ; changes involving overrunning are 

 expensive. In general, the publisher cannot undertake to assume the cost of more 

 than minor corrections in the proof. All corrections should preferably be made 

 in ink. 



Foot notes should be numbered consecutively from 1 up. 



The following is an example of the system of references employed, the volume 

 being given in heavy faced type: 



Am, J. Sci., 44, 249, 1917. The year should be given in every case; this 

 renders a series number unessential. 



Thirty separate copies of each article will be furnished to the author free of 

 cost and without previous notice from him. They will be provided with a plain 

 cover (but with reference to volume and year). If the author orders separate 

 copies, they will be understood to be in addition to the thirty mentioned above, and 

 he will receive a bill for the extra expense involved, as also for that of a printed 

 cover (with title, etc.), when this is specially ordered. These charges will be as 

 follows; the rates will be increased if the article is accompanied by plates, or 

 involves unusual expense, (e. g., during existing conditions). 



No. Copies. 



50 



100 



200 



300 



500 



8 pages 



16 " 



$2.25 

 3.50 

 4.75 



$2.75 

 4.25 

 5.75 



$3.50 

 5.25 

 7.00 



$4.25 

 6.25 

 8.25 



$5.50 



8.00 



10.50 



24 " _.. 





Cover 



$1.00 



$1.25 



$1.75 



$2.25 



$3.00 





Subscription price $6 per year, or 50 cents a number, postage prepaid in the 

 United States; $6.25 to Canada; $6.40 to foreign subscribers of countries in the 

 Postal Union. A few sets on sale of the early series. Ten-volume index 

 numbers on hand for the second and third series. 



Ten-volume Indexes, Yols. I-X, XI-XX, XXI-XXX, XXXI-XL, fourth 

 series price one dollar each. 

 Address, 



THE AMERICAN JOURNAL OF SCIENCE, 



ISTew HI a veil;, Oorm.. 



2 





