Captain PuUen on Deep-sea Soundings. 461 



several of 50 and 80 fathoms. The first was 1110 fathoms down by 

 intervals, but no valve coming in, it appearing to have been broken 

 off from the rod by striking some hard substance, either at the 

 bottom or on its passage up or down, I immediately determined on 

 getting another cast, although darkness was coming on. The 

 weather fortunately was calm with very little sea on ; so stationing 

 a number of lanterns, the lead was at once dropped over the bows, 

 and as satisfactory a cast was got as could possibly be wished, the 

 sinker striking bottom by intervals at 11 20 fathoms, thus proving 

 the correctness of the first sounding, and finally, the valve coming in 

 with a sufficient portion of bottom to prove it again. This specimen 

 consisted of what appeared to the eye very fine sand covering a hard 

 substance (coral I suspect), but under the microscope it was found 

 to be some of the most beautiful specimens of Diatomacese that can 

 be imagined. 1 send home these specimens, small as the quantity 

 is, being quite sufficient for examination. The next morning further 

 to N.E. with 800 fathoms, no bottom: another cast still further 

 N.E., bottom with 900 fathoms, bringing up another specimen of 

 the same sort of sand as last niglit, with a small pebble amongst it. 



[Capt. PuUen here explains how his attention was drawn to j^arts 

 of the sea where the surface was covered, for a considerable space, with 

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

 with strips of deep blue water between ; j^i'oducing 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 4(f 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 15/0 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 5l°'5. The maximiun tell-tales at the two least depths came 

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

 its minimum showing an increasing temperature after passing through 

 tlie colder stratum, is quite jjroof enough of its tell-tale fixlHng 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 tlie thermometer at H80 fathoms shows the temperature of. 



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



