10 REPORT ON 



XII on the after turret was 5.5 inches to port. While we were lying at Callao 

 the ship was perfectly free to swing to the tide, but the wind and current were so 

 strong that she did not do so, but always lay with her head pointing in a southerly 

 direction. 



The observations taken on shore, April 26th, were made on the northeast side of 

 San Lorenzo Island, about two and a half miles southeast of the light-house. The 

 island is a mass of hills, rising to an elevation of more than a thousand feet, com- 

 posed of loose friable rock which seems to be of volcanic origin, and which is con- 

 stantly disintegrating into a fine yellow sand. The place selected for making the 

 observations is at the foot of a gorge where there is a beach, about a quarter of a 

 mile long, of the yellow sand mentioned above. On the beach stand a number of 

 fishermen's huts, and a few steps back, at the foot of the gorge, stands a large, 

 square, two-story house. The spot where the instruments stood is on the southeast 

 end of the beach, a little beyond the fishermen's huts, and just above high-water 

 mark. Assuming the position of the light-house to be lat. 12° 4' 0" S., long. 5 h 

 9 m 18 s .O W., the position occupied by the instruments is in 



Lat. 12° 5' 14" S. 



Long. 5 h 9 m 9\1 W. 



The place was carefully tested for local attraction by taking fore and back sights 

 with a compass, but none could be detected. 



Patta, Peru. We remained in this port only from 2 h 30 m P. M. of May 6th, 

 1866, till 6 h P. M. of May 7th, and there was neither time nor opportunity to swing 

 the ship. However, a complete set of magnetic observations were made on shore 

 at a station on the beach four-tenths of a mile northwest of the large iron building 

 which stands just back from the mole, and is used by the government as a custom- 

 house, etc. As nearly as could be determined from angles carefully measured, 

 and plotted on the English Admiralty Chart, this station is identical with the one 

 occupied by the officers of H. B. M. surveying vessel "Beagle," in the year 1836, 

 when making their observations for determining the position of Payta. According 

 to their determinations it is in 



Lat. 5° 5' 36" S. 

 Long. 5 h 24 m 22 9 .0 W., 



the longitude depending upon the position of the northeast bastion at Panama, 

 New Granada, which is taken to be 5 h 18 m 4 S .6 W. 



The instruments were set up, just above high-water mark, on the gray sand 

 beach, about fifty feet back from which the land rises into bluffs, two hundred feet 

 high, composed of a hjard yellow earth, alternating with sedimentary rocks. The 

 station was carefully examined for local attraction, by taking fore and back sights 

 with a compass, but none could be detected. 



Panama, Neio Granada. The ship was swung in this roadstead, on May 20th, 

 1866, in the usual manner. Her position at the time was lat. 8° 55' N., long. 79° 

 30' W. Joint XII on the after turret was 5.5 inches to port. While we were 

 lying here the ship was swinging freely in all directions to the wind and tide. 



