538 American Philosophical Society. 



N. Appearance of dark lines extending into the sun's disc, no- 

 ticed by Nos. 3, 4, 10, and 14. The time noted by Nos. 3 and 14, 

 as the end of the eclipse. 



O. End of Eclipse, inferred by each observer from his notes. 



P. Final disappearance of the dark lines, the sun's disc having 

 resumed its natural shape, Nos. 3, 4, 10, and 14, inferred the time 

 of O as at some instant intermediate between N. and P. The time 

 of external contact difficult to determine on account of this irregu- 

 larity. 



For the convenience of computers the local times above given 

 have been reduced to their corresponding value for the State-House 

 by E. O. Kendall, by means of his formulae, in vol. xx. of the Journal 

 of the Franklin Institute, p. 125, which gives the following values 

 for the variation of the local times of the several phases, for a small 

 variation of terrestrial latitude or longitude as follows : 



Beginning. Ring. End. 



Variationfor 4- ornorth 1 _Q.Q3gy -0-0382 -0-0343 



1" terr. lat. J 



Variation for + or east 1^ 1 = + j-qgOO 4- M400 +0-9925 



of terr. long, in time. . J 

 The means of his results for the State-House giving to each ob- 

 ser^'ation its proper weight in mean time of the State-House, are, 



Beginning S'' 13" 10^-06 



Formation of ring 4 31 18 "76 



Rupture of ring 4 35 31 '35 



End 5 45 15-46 



Duration of eclipse 2 32 5-40 



Duration of ring 4 12 '59 



Dr. Patterson read a paper by Professor Charles Bonnycastle, of 

 the University of Virginia, containing " Notes of Experiments made 

 August 22 to 25, 1838, with the view of determining the depth of 

 the Sea by the Echo." 



This paper, which was not offered for publication in tlie Society's 

 Transactions, states that the generally received notions in regard to 

 the intensity of sound in water, and the distance to which it is con- 

 veyed, had suggested to Mr. Bonnycastle some years ago, the idea 

 that an audible echo might be returned from the bottom of the sea, 

 and the depth be thus ascertained from the known velocity of sound 

 in water. The probability of this view was deemed at least suffi- 

 cient to justify an experiment ; and accordingly the Navy Com- 

 missioners authorized the construction of the necessary apparatus, 

 and Captain Gedney, of the U.S. brig Washington, attached to the 

 coast survey, volunteered his services, and the use of his vessel, and 

 authority to this effect was liberally granted by the Secretary of 

 the Treasury, Mr. Woodbury. 



The apparatus, which is fully described in Mr. Bonnycastle's 

 paper, consisted first of a petard or chamber of cast iron 2| inches 

 in diameter, and 5^ inches long, with suitable airangements for 

 firing gunpowder in it under water ; secondly, of a tin tube, 8 feet 

 long and 1| inch in diameter, terminated at one end by a conical 



