43 



James Ross describes the upthrow of this warm layer of 

 water caused by the southerly submarine current from the 

 tropics meeting the gradual rise of the sea bottom as it 

 approaches land. And Dr. Murray, in the paper already 

 referred to, says that " these deep layers of relatively warm 

 water appear likewise to be slowly drawn southwards to the 

 Antarctic a»-ea, to supply the place of the ice-cold currents of 

 surface water drifted to the north. This warm underlying 

 water is evidently a potent factor in the melting and 

 destruction of the huge table-topped icebergs of the Southern 

 Hemisphere." The difference between the temperature of 

 the surface and underlying water in the deep basin crossed 

 by Weddell is shown by Boss's sounding in it when he reached 

 no bottom with a 4,000 fathom line, and when with a surface 

 temperature of the water of 30'8 deg. he found a 

 temperature of 395 deg. at 1,050 fathoms — the greatest 

 depth to which he could trust his self-registering thermo- 

 meters. 



Eoss's tracks within the Antarctic Circle in 1842 and 1843,. 

 between 170 deg. east and 160 deg. west longitude, took 

 him across no such deep basin, for the soundings varied from 

 about 1,600 fathoms on the Circle to 150 as he approached 

 land. But the influence of the warm underlying current 

 from the north was always noticeable, the temperature of 

 39-8 deg. being repeatedly found at 600 fathoms with a, 

 surface temperature below freezing point ; and at his farthest 

 south, with soundings of only 250 fathoms, the shoaling had 

 brought the warmer water to the surface where its temper- 

 ature was 32 deg. with a mean air temperature of 27 deg. 

 The temperature of the sea at the bottom was 33'2 deg. 



In a conversation I had the other day with Captain Pascoe, 

 he incidentally mentioned another factor that may have much 

 influence in keeping an open sea in the neighbourhood of 

 Eoss's tracks in 1841 and 1842. These tracks pass along 

 what is probably the main line of the earth's volcanic and 

 seismic action in the southern hemisphere — -the line marked 

 by the New Zealand volcanoes and Mount Erebus. Earth 

 tremors would certainly do much to help forward the action 

 of the water on the great ice barrier that guards the coast 

 of Victoria Land. 



It must always be borne in mind that our knowledge of 

 Arctic regions enables us to predicate very little in connection 

 with Antarctic. The circumstances of the two poles — and 

 especially the meteorological circumstances — are so entirely, 

 and, at present, so unaccountably, different, that reasoning 

 from Arctic data is almost inevitably misleading with 

 relation to Antarctic facts and conditions. All navigators 

 who have been in both are continually recording how unlike 

 the one polar region is to the other. Many of the meteor- 



