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a white milky substance, apparently of animal nature, in large patches, 

 with strips of deep blue water between ; producing an effect which, 

 viewed from a distance with a glass, had very much the appearance 

 of breakers ; and he suggests that some of the reports of shoals and 

 breakers between the parallels of 35 and 40 may have no better 

 foundation than the phenomenon in question.] 



Steering now to pass to the east of Mauritius, a little south of the 

 parallel of 20, about 90 miles from the land I got no bottom with 

 1375 fathoms of line, which gave me the first idea, that what I had 

 before thought of the Indian Ocean not being so deep as the Atlantic 

 was wrong. Proceeding northward, I passed west of Cargados 

 Garazos, Saya de Malha, east of Seychelles, and crossed the Equa- 

 tor in 58 20' E. ; getting a cast 9 miles south of it with 2380 fathoms, 

 no bottom. This is the sounding alluded to in a former part of this 

 letter. 



Forty or fifty miles west of the northern part of Cargados, 1400 

 fathoms of line reached the bottom. In 14 41' S., 58 43' E., 

 no bottom with 1570 fathoms; 10 30' S., and 58 52' E., no 

 bottom with 1320 fathoms. At this cast I sent down three 

 thermometers at the 1320, 880, and 440; the minimum at the 

 greatest depth 51*5, at the centre depth 41*5, and at the least 

 depth 51'5. The maximum tell-tales at the two least depths came 

 in all right, but that of the greatest depth had fallen 6; and 

 its minimum showing an increasing temperature after passing through 

 the colder stratum, is quite proof enough of its tell-tale falling down 

 too, at least down the column instead of remaining up at what it once 

 must have been in passing through that stratum, which the tell-tale 

 of the thermometer at 880 fathoms shows the temperature of. 



Winds now light and northerly. I got close to the doubtful 

 George Island, and three quarters of a mile west of its southern point, 

 bottom was not reached with 2000 fathoms of line. I then passed 

 over it nearly a mile within its southern point, and having no signs of 

 being on shore, I conclude that no such island ever existed in the 

 position given it on our charts ; and I find no account of it in 

 Horsburgh. 



Steaming now for Rose Galley Rocks, five miles south of the most 

 western of them, I got bottom with 2254 fathoms of line, and 

 brought up a plentiful supply of bottom, as well as the minimum 



p 2 



