MAGNETIC OBSERVATIONS. 



33 



Monadnock, and Custom-house were not measured simultaneously, and as the two 

 ships were riding at anchor with a considerable amount of chain out, it is probable 

 that they shifted their positions after the angle at the Powhattan was measured, 

 and before the angles at the Monadnock and Custom-house were taken. This will 

 account for the excess of the sum of the three angles over 180. 



In the accompanying sketch the different points are designated as follows : 



A = Point Macoripie Light-house. 



B = Northeast corner of Custom-house on the wharf. 



C = U. S. Iron-clad Monadnock. 



D = U. S. Sloop of War Powhattan. 



E = most southern of the two steeples on the Church of the Conception. 



F = most southern of the two steeples on St. Joseph's Church. 



M = Magnetic and Astronomical Station of December 13th and 14th. 



Scale: 1 inch = 4000 feet. 



The observed angles were as follows: 



Angles at D. 



A to B = 101 35' 

 B to C = 25 13 

 vi to C = 1 26 49 



Angles at D. 



A tC #=10! 36' 



24 57 



Bio C = 



March, 1872. 



