SECTION II. 



DESCRIPTIONS OF STATIONS. 



UNLESS otherwise stated, the assumed positions of light-houses, forts, etc., have 

 been taken from the English Admiralty Charts, or from the English Admiralty 

 List of Lights, the latest editions obtainable in 1865 being employed. The longi- 

 tudes are counted from the meridian of Greenwich. 



The method used in testing a station for local attraction by means of fore and 

 back sights with a compass, was as follows : The compass was set up at the station, 

 and the bearing of a point distant one hundred yards, or more, was observed. 

 Then the compass was transferred to that point, and the bearing of the station was 

 observed. These two bearings should evidently differ from each other by 180; if 

 they did not, it was certain that local attraction existed at one or both of the points, 

 and a new station was sought for. This process is almost certain to detect any 

 strictly local magnetic attraction, but it will not suffice to demonstrate the existence 

 of an abnormal state of the magnetic elements extending over a large territory. 



PHILADELPHIA, Pa. The magnetic observations were made at a spot on the east 

 bank of the Delaware river, about twenty feet from the water's edge. It is nearly 

 southeast from the U. S. Navy Yard, from which it is distant about three-quarters 

 of a mile. The soil is a dark nearly black earth, which appears to have been 

 deposited by the river. The approximate position of the station was 



Lat. 39 55' N. 

 Long. 5 h O ra 32" W. 



GOSPORT, Va. The magnetic observations were made on a white sandy beach, 

 on the west bank of the Elizabeth river, about thirty feet from the water's edge. 

 From the place where the instruments stood, the flagstaff in the U. S. Navy Yard 

 bore due north by compass, and was distant about half a mile. 



Assuming the position of the flagstaff to be lat. 36 49' 32" N., long. 5 h 5 m 9".8 W., 

 as stated by the authorities at the Navy Yard, the position of the spot occupied by 

 the instruments is approximately 



Lat. 36 49' 0" N. 

 Long. 5 h 5 m 9.8 W. 



The ship was swung at the compass station in Hampton Roads, on November 

 , in the usual manner. Her position at the time was lat. 36 58' N long 

 76 20' W. Joint XII on the after turret was 14.4 inches to port 

 (4) 



