UPTTIBXJO-A-TIOIISrS 02P TJECIE 



JOHNS HOPKINS UNIVERSITY, 



I. American Journal of Mathematics. S. Newcomb, Editor, and T. Craig, 



Associate Editor. Quarterly. 4to. Volume XI in progress. $5 per 

 volume. 



II. American Chemical Journal. — I. Remsen, Editor. 8 Nos. yearly. 8vo. 



Volume XI in progress. $4 per volume. 



III. American Journal of Philology. — B. L. G-ildersleeve, Editor. Quar- 



terly. 8vo. Volume IX in progress. $3 per volume. 



IV. Studies from the Biological Laboratory. — Including the Chesapeake 



Zoological Laboratory. H. N. Martin, Editor, and W. K. Brooks, Asso- 

 ciate Editor. 8vo. Volume IV in progress. $5 per volume. 



V. Studies in Historical and Political Science. — H. B. Adams, Editor. 



Monthly. 8vo. Volume VII in progress. $3 per volume. 



VI. Johns Hopkins University Circulars. — Containing reports of scientific 



and literary work in progress in Baltimore. 4to. Vol. VIII in progress. 

 $1 per year. 



VII. Annual Report. — Presented by the President to the Board of Trustees 

 reviewing the operations of the University during the past academic year. 



VII. Annual Register. — Giving the list of officers and students, and stating 

 the regulations, etc., of the University. Published at the close of the Aca- 

 demic year. 



BECKER BROTHERS, 



No. 6 Murray Street, New York, 



Manufacturers of Balances and Weights of Precision for Chem- 

 ists, Assay ers, Jewelers, Druggists, and in general for every use 

 where accuracy is required. 



AMERICAN JOURNAL OF SCIENCE. 



Founded by Professor Silliman in 1818. 



Devoted to Chemistry, Physics, Geology, Physical Geography, Mineralogy,. 

 Natural History, Astronomy, and Meteorology. 



Editors: James D. Dana and Edward S. Dana. 



Associate Editors: J. P. Cooke, Jr., George L. Goodale, and John Trow- 

 bridge, of Cambridge, H. A. Newton and A. E. Verrill, of Yale, and G. P. 

 Barker, of the University of Pennsylvania, Philadelphia. 



Two volumes of 480 pages each, published annually in MONTHLY NUMBERS* 



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

 second series of 50 volumes as a two-monthly in 1870. The monthly series com- 

 menced in 1871. 



Twenty copies of each original communication are, if requested, struck off for 

 the author without charge ; and more at the author's expense, provided the num- 

 ber of copies desired is stated on the manuscript or communicated to the printers 

 of the Journal. 



The title of communications and the names of authors must be fully given. 

 Articles should be sent in two months before the time of issuing the number for 

 which they are intended. Notice is always to be given when communications 

 offered, have been, or are to be, published also in other Journals. 



Subscription price $6; 50 cents a number. A few sets on sale of the first 

 and second series. 



Address the Proprietors, 



J. D. and E. S. DANA, New Haven, Conn. 



