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 B. 





Angles at C. 



D to A = 55° 12' 

 D to C = 84 17 

 F to C = 73 12 

 E to C =125 6 

 E to F = 52 15 

 A to £ = 95 6 





D to A = 36° 19' 

 £> to B = 71 14 

 Bto F= 42 28 



i? to j5 = 1 5 40 



From these we obtain the following corrected 



Angles at B. 





Angles at C. 



A to £ = 95° 11' 

 £ to F = 52 9 

 F to C = 73 14 

 C to D = 84 5 

 2)10^=55 21 





D to />' = 70° 58 

 Z> to ^ = 36 14 

 ^ to B = 34 44 

 B to /s = 15 40 

 E to F= 26 48 



6 Maroh, 1872. 









Angles at D. 



A to B = ioi° 35' 

 2? to C = 25 13 

 A to C = 126 49 



Angles at D. 



A tc B = 101° 36' 

 ^to C= 24 57 



