The comparison of our magnetic instruments 1843 was completed in a few days, and we sailed again, May 20.on the 20th, for the Island of Ascension, and without any events worthy of notice, arrived there on the 25th. Our magnetic experiments, before and after crossing the line of no dip, are of peculiar interest, and will be published with the rest of our magnetic observations, under the supervision of Colonel Sabine. In the Appendix to this volume will be found a table, containing our position at noon every day of the remainder of our voyage, the magnetic dip and variation, and the direction and strength of the current.
From Captain Dwyer, of the Royal Marines, May 29.commandant of the island, we received every attention and a supply of turtle for both ships, and we proceeded on our voyage at 9 a.m. of the 29th, steering for Rio de Janeiro.
We found the temperature of the air vary from 74° to 83°, and the surface of the sea from 75° to 77°, at this period of the season. The total absence of all sea-fowl is as remarkable here as in all other parts of the tropics we have visited, except only where small isles have been projected from the depths of the ocean, and afford them resting and breeding places.
On the 3rd of June, when in latitude 15° 3′ S., June 3.and longitude 23° 14′ W., being nearly calm and the water quite smooth, we tried for, but did not obtain, soundings with 4,600 fathoms of line, or