235 



some analytical advantage; and an expert computer will use them 

 and their adjunct differential expression with equal facility in refer- 

 ence to the mean instant of his data. The author appears to have 

 had considerable experience in testing their practical application, and 

 from such, gives a partiality to his leading formulas, as connected 

 with the more favourable position of the star, and as having brevity 

 and easy recollection to recommend them. In concluding his paper, 

 he mentions " Puissant Geodesie," (edition of 1842,) and Strune's 

 Gradmessing, as standard writers in France and Germany, on these 

 and similar subjects. He regretted not having the advantage of see- 

 ing these works, and referred to them only through a notice of Prof. 

 A. D. Bache, Superintendent of the Coast Survey, who has sent to 

 him a short transcript of two formulae (one from each work), which 

 are different from those forming the principal objects of his paper, 

 and which must be seen in their respective authors, to seize their ap- 

 plication and their presumed advantage. 



Professor J. C. Cresson gave a brief account of the demoli- 

 tion of Mr, Paul Beck's shot tower, in the western part of the 

 city. The height of the structure was about 160 feet, and the 

 walls six feet in thickness at the base. 



The walls were cut away near the base on the whole of the north- 

 ern side, and partly on the eastern and western, the parts thus un- 

 dermined being temporarily supported by shores of timber. When 

 the undermining was completed, an unsuccessful attempt was made 

 to remove the shores by means of gunpowder ; and while the work- 

 men were preparing a second charge of powder, the base of the 

 building was suddenly protruded toward the south, and the whole 

 fabric crumbled into fragments, collapsing, as it were, upon its own 

 base, and the ruins occupying but little more ground area than the 

 original structure. 



The following communication, relating to observations made 

 at the Washington and Philadelphia High School Observato- 

 ries, on the two Biela comets, was brought before the Society, 



by Dr. Patterson, 



Washington, D. C. Feb. 5, 1846. 



Dear Sir, — I send you the measures of the position and distance 

 of the two Biela comets, made at the Washington and High School 

 Observatories. The angles of position are measured from the north 

 round the circle eastward. The time is mean time, Washington Ob- 

 servatory. The results are as yet only approximate, not having 

 been rigorously computed. 



