[ 120 ] 10 



The investigations mentioned in the foregoing account have been at- 

 tended with very laborious arithmetical calculations. A small appropria- 

 tion has been made to defray, in part, the expense of these. Indeed, 

 without the aid thus given, the discoveries we have related would 

 scarcely have been made — at least at this time, and in our country. 



2. The next m.emoir is an account of the discovery of a comet by Miss 

 Maria Mitchell, of Nantucket, with its approximate orbit, calculated by her- 

 self. The honor of this discovery has been duly awarded to the author. A 

 medal has been presented to her by the King of Denmark, and the comet 

 itself is now known to astronomers in every part of tlie world by her 

 name. From the peculiarities of the case, the Executive Committee re- 

 commended that a small premium be presented to Miss Mitchell. 



3. The third memoir is 07i a new method of solving cubic equations, by 

 Professor Strong, of Neio Brunswick, Neiv Jersey; a purely mathematical 

 paper, which has been pronounced an interesting addition to that branch of 

 science. 



4. The fourth memoir is a contribution to the physical geography of the 

 United States. It presents a section, from actual surveys, of the descent 

 of the bed of the Ohio river from its source, in the State of New York, to 

 its mouth, on the Mississippi. By a series of observations and elaborate 

 calculations, the author exhibits the amount of water which passed down 

 the river during a period of eleven years prior to 1849. This, compared 

 with the amount of rain which fell during the same time on the surface 

 drained by the river, gives a series of interesting results in reference to 

 evaporation. 



It also contains a proposition for improving the navigation of the Ohio, 

 founded upon data given in the preceding part of the memoir. Whatever 

 may be the result of the plan here proposed, this memoir has been recom- 

 mended for publication as a valuable addition to the physical geography of 

 the United Slates. The author is Charles Ellet, jr., the celebrated engi- 

 neer of the wire bridges over the Niagara and Ohio rivers. Another me- 

 moir is promised by the same author, which will be a continuation of the 

 same subject. 



5. The fifth memoir is contributed by Dr. Robert Hare, of Philadelphia, 

 and is intended to elucidate the remarkable phenomenon exhibited at the 

 great fire in the city of New York on the 19th of July, 1845, during which 

 two hundred and thirty houses were destroyed, containing merchandise 

 amounting in value to sixty-two millions of dollars. "A series of detona- 

 tions, successively increasing in loudness, were followed by a final explo- 

 sion which tore in pieces the building in which it took place, threw down 

 several houses in its vicinity, and forced in the fronts of the houses on the 

 opposite side of the street." These effects were attributed to gunpowder, 

 though the owner of the building in which the explosion occurred declared 

 that none of this article was present, but that the house contained a large 

 quantity of nitre, in connexion with merchandise of a combustible nature. 



This memoir contains a series of investigations relative to the explosions 

 which may be produced by heated nitre in connexion with carbonaceous 

 matters. The author shows, by numerous experiments, that explosions of 

 a violent kind can be produced by forcibly bringing into contact at a high 

 temperature, nitre, and substances of an inflammable character, [t also con- 

 tains several new experiments on the combustion of gunpowder under 

 different circumstances. 



