ANtflYEESABY ADDEESS. 11 



run from Brazil, except at a depth of fifty fathoms ; the lowest 

 surface temperature being 54° F. 



On the diagrams which were exhibited at the Conversazione. 

 we saw also depicted the extraordinary way in which the islands 

 of the Atlantic, such as Madeira, the Azores, Teneriffe, Bermuda, 

 St. Paul's Bock (the most striking of all), St. Thomas's (in the 

 West Indies), and Fernando de Noronha, as well as the Cape of 

 G-ood Hope, rise from the sea-bottom at a Tery small angle 

 through the ocean which, at a short distance is of enormous 

 depth. The escarpments are almost perpendicular. For example, 

 the base of Bermuda, at a depth of from 2,500 to 2,650 fathoms, is 

 but 120 miles broad ; whilst the base of Madeira is distant only 

 90 miles from that of the Azores at the same depth of 2,656 

 fathoms ; the temperature being — at Bermuda 35°, at Madeira 

 357°, and at the Azores 353°. Off the Cape of Good Hope, at 

 a distance of 35 miles, the temperature was 32*9° at a depth 

 of 2,325 fathoms. The base of St. Yincent and St. Jago Islands 

 (which are separate spires or horns rising from the base at a 

 distance of 110 miles) is only 300 miles wide at a depth of 2,100 

 fathoms. The actual base of St. Paul's Bock, a mere speck on 

 the surface, has a base of 115 miles' at a depth of 1,900 fathoms, 

 the surface temperature being 75°, and the bottom 358°. 



Fernando JNToronha has a base of only 45 miles at a depth of ■ 

 2,150 fathoms ; the temperature of the water at that depth (236m. 

 S. of the Equator) being only about 33°, whilst at a depth 

 on one side of 2,475 fathoms the temperature was 32'4° (just 

 above freezing-point), and on the other or Brazil side the 

 temperature was 33*2° at a depth of 2,275 fathoms. The tem- 

 perature of 32*2° was also that of the ocean at a depth of 2,550 

 fathoms, between the Cape of Glood Hope and Tristan d'Acunha, 

 in latitude 37° 6' S., 710 miles from the former. These examples 

 are taken from the diagrams ; but it is to be observed that, if they 

 had been drawn to equal scales, the actual elevations and 

 breadths of the basis would not have shown the same differences. 

 Then the bottom of the Atlantic would have been represented by 

 a line of apparently small undulations between the islands, and 



