CONTEI^TS OF YOL. XII. 



PAGE 



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ARTICLE I. (No. 181.) Review of American Bikds, in the Museum 

 OP THE Smithsonian Institution. Part I. By S. F. 

 Baikd. 1864-1872. Pp. 484. 



ARTICLE II. (No. 255.) The Constants of Nature. Part I. Spe- 

 cific Gravities ; Boiling and Melting Points ; and 

 Chemical Fokmul-s;. Compiled by F. Wigglesworth 

 Clarke, S. B. December, 1873. Pp. 272. 



ARTICLE III. (No. 263.) Telegraphic Announcements of Astro- 

 nomical Discoveries. By Prof. Joseph Henry. April, 

 1873. Pp. 4. 



