92 DISCOVERY REPORTS 



convergence the majority of our observations are in the Antarctic zone and the southern 

 part of the sub-Antarctic zone. In September 1932 a W-shaped cruise (sections 12, 

 14, 15 and 16) was made in the South Pacific consisting of four sections, one of which, 

 from Wellington to the ice-edge in 6i° 07' S, 153 57-2' W, has already been discussed. 

 The other sections were from the ice-edge north of the Ross Sea in a north-east direction 

 to a point 41 63' S, 126 04' W in the central part of the ocean, from there in a south- 

 east direction to 63 57' S, 101 16' W and then north-eastwards to the western entrance 

 to the Magellan Strait. At the ice-edge north of the Ross Sea the silicate contents at the 

 depths of maximum temperature and salinity were 385011^. and 4500 mg. and they 

 decreased towards the north-east until just north of the Antarctic convergence the 

 corresponding values were 1200 mg. and 3600 mg. In the sub-Antarctic zone the depth 

 of the current was greater, so that in the south the depth of maximum salinity was 

 found at about 2500 m. and at the most northerly station at 4000 m. The silicate content 

 at the depth of maximum salinity increased from 2750 mg. just south of the convergence 

 to a value of 3600 mg. in the south of the sub-Antarctic zone and 4300 mg. at the most 

 northerly station. 



From the mid-South Pacific station in 41 03' S, 126 04' W the silicate content at 

 the depth of maximum salinity in the sub-Antarctic zone at first increased south-east- 

 wards from a value of 4300 mg. to one of 5500 mg., and then, just north of the Antarctic 

 convergence, dropped to 4050 mg. The section did not quite reach the ice-edge, but 

 in 63 57' S the content at the salinity maximum was 4550 mg. From 63 57' S the 

 content decreased north-eastwards to 3550 mg. just south of the Antarctic converg- 

 ence, but north of this boundary it increased again to 4100 mg. in 55" 18-4' S, 

 8o°o8-i'W. 



In 1934 a considerable number of observations were made along the ice-edge region in 

 this ocean in the months of January, February and March in the course of two cruises : 

 a westward cruise from 8o° W to the eastern entrance to the Ross Sea and a return 

 eastward cruise from 171^° to 8o° W. The return journey was made at a slightly higher 

 latitude owing to the retreat of the ice during the interval between the cruises ; altogether 

 thirty-two deep stations were made. In the course of the westward cruise, except for 

 the extreme eastern stations where the upper part of the warm deep water contained 

 4000-4300 mg., the silicate content in this part of the current increased from east to 

 west, being about 3000-3300 mg. in the east and 4600-4700 mg. in the west. Similarly 

 the content at the depth of maximum salinity increased westwards from values about 

 3500-4000 mg. in the east to 5000-5300 mg. in the west, the extreme eastern part of 

 the ocean being again excepted. The depth of the warm deep current also changed from 

 east to west; the upper layers were found at 600-800 m. in the east, about 400 m. in the 

 central part of the ocean and about 300 m. in the west, the maximum temperature of 

 the layer falling from about 2° C. in the east to 1-4° C. in the west. Similarly, the depth 

 of the salinity maximum of the layer changed, being about 1000- 1500 m. in the east 

 and about 500-600 m. in the west. 



On the return eastward cruise, except for stations in the extreme east, the silicate 



