Dubois. I 226 I'^'^y- 



United States," prepared by Drs. Wood and Bache, two of 

 the Presidents of the Society. The progress during the last 

 two centuries, not only of Botany and Mineralogy and other 

 sources of the Materia Medica, but of the general methods 

 of science, is remarkably illustrated by a comparison of the 

 two books. 



Pending nomination No. 494 was read : 



And the Society was adjourned. 



Stated Meeting, May 15, 1863. 



Present, seventeen members. 



Dr. Wood, President, in the chair. 



Letters accepting membership were received from William 

 Dwight Whitney, dated New Haven, April 2 1st; from E. A. 

 Washburne, dated Philadelphia, May 2d ; and from James 

 Pollock, dated Philadelphia, May 14th, 1863. 



Letters to the Librarian, inclosing photographs of the 

 writers, were read, from B. Silliman, Sr., of New Haven, 

 Josiah Quincy, of Boston, and Gen. Swift, of Geneseo, in the 

 State of New York. 



Donations for the Library were announced from the Essex 

 Listitute, the Museum of Comparative Zoology, in Boston; 

 the American Journal of Science and Art, Blanchard & Lea, 

 and Dr. Parrish, of Philadelphia; Professor J. H. Alexander, 

 of Baltimore, and the Academy of Sciences in St. Louis. 



Mr. Dubois communicated the following remarks on assay- 

 balances : 



The recent receipt of two assay-beams at the Mint, procured for 

 the use of Dr. Munson, assayer of the new branch Mint at Denver, 

 in the Territory of Colorado, furnishes occasion for a few remarks 

 on the progress of this delicate branch of art. 



Thirty-one years ago, when Mr. Eckfeldt, the present assayer of 

 the Mint, entered upon that office, he found that the beam on which 

 all his operations were to turn, would not itself turn with a less 

 weight than about the one-fiftieth part of a grain. Consequently, 

 the nearest report of the fineness of gold was by gradations of one 



