151 



approximate times of maximum and minimum could be infer- 

 red; but that, in order to render the determination of the pe- 

 riods of their occurrence more accurate, additional observations 

 at every six minutes were now made (since January 1) within 

 the limits shown by the curves, presented this evening, to be 

 those of the occurrence of maxima and minima. 



The Committee on the Hall reported that the articles be- 

 queathed to the Society by the late Mr. Vaughan, as well as 

 those presented by Mr. Jacob Snider, Jun., were now in its 

 possession. 



Stated Meeting, March 18. 



Present, twenty-seven members. 



Mr. Du Ponceau, President, in the Chair. 



Letters were read: — 



From the Royal Academy of Sciences of Berlin, dated 15th 

 Aug. 1841, acknowledging the receipt of the Transactions and 

 Proceedings of the Society, and of the American Almanac for 

 1841; and notifying the transmission of their Transactions for 

 1S39, and their Monthly Reports from July, 1840, to June, 

 1841:— and 



From the Royal Academy of Sciences of Brussels, dated 18th 

 Aug. 1841, acknowledging the receipt of copies of the So- 

 ciety's Transactions and Proceedings. 



The following donations were announced: — 



FOR THE LIBRARY. 



A Catalogue of Books. Henry G. Bohn, York Street, Covent Gar- 

 den. 8vo. of 1948 pages. London, 1841. — From Mr. Henry 

 G. Bohn. 



Zoological Contributions. On some American Species of Hydrach- 

 nidse. By S. S. Haldeman. No. 1. 8vo. 1842.— From the 

 Author. 



Boston Journal of Natural History. Vol. IV. No. 1 . 8vo. Boston, 

 1842. — From the Boston Society of Natural History. 



