SPEED OF THE COLD BOTTOM WATER 213 



until 61 years later that it was finally disproved by Bruce who, when sounding over the same position 

 in March 1904, got 2666 fathoms, ' blue mud '. While paying characteristic tribute to the pioneer work 

 of Ross, Bruce (1905, 191 1, p. 173) points out that the cumbrous hempen line Sir James had used had 

 on this occasion ' evidently sagged, after the weights had touched the bottom — if they touched at all — 

 the Une being carried away by the strong currents that exist in that region ', and from Bruce's own 

 account of this locality which I quote below there can be little doubt that the strong currents to which 

 he alludes are in fact to be identified with the movement of the Antarctic bottom water. 



It seems fairly certain that Bruce's explanation of this now famous hydrographic failure is correct, 

 and that the more obvious one that Ross had simply paid out too much line through failing to notice 

 his sinkers had reached the bottom does not apply. For Ross, now nearing the end of his long 

 circumpolar voyage, was by this time well practised in the use of his primitive sounding gear, with 

 which, despite the immense labour^ involved in its operation, he had hitherto been highly successful. 

 Conditions, moreover, were ideal for sounding and there seems every reason therefore to suppose 

 that but for some such unusually strong interference by undertow as Bruce himself was later to 

 encounter, Ross would have been aware he had struck bottom that day just as he had been so often 

 before. That in fact he had was demonstrated long afterwards by Gould (1924) who, from data supplied 

 to the Admiralty by Ross in July 1843, plotted the times taken for each 100 fathoms of line to run 

 out, showing from the sudden and pronounced increase in the retardation of the speed of the 

 descending line at 2200 fathoms, that it was clearly at about that level that contact had been made. 

 Both Brown (1923) and Gould (1924), however, call attention to the deep interference Ross must have 

 encountered. Brown remarking, 'Thus ended the mythical Ross deep. Undoubtedly the strong 

 under-current had caught Ross's lines and misled the world for sixty years '. 



Bruce's own experience in this region is equally interesting. On 19 March 1903 he records that 

 'in a depth of 122 1 fathoms, the trawl was lowered, putting out 2000 fathoms (= 2\ miles) of cable, 

 but it did not touch the bottom '. Here again it must be emphasised that since Bruce, like Ross before 

 him, was by this time already well practised in his craft, having developed a highly efficient deep- 

 water trawling technique, it is unlikely that his failure to reach bottom in this instance was due to 

 any mishandling of his gear. The only way it could be accounted for he says was 'that there were 

 strong under-currents sweeping the trawl off the bottom '. It was not, moreover, an isolated experience 

 for it had 'occurred more than once in this locality' and this in spite of the fact that the trawl warp, 

 against this very contingency, had been heavily overweighted with ' four furnace bars, each weighing 

 22 lbs., and two olive-shaped weights, each of 20 lbs.'. Pirie and Brown (1905), referring to the diffi- 

 culties of sounding in Ross's time, also call attention to the strong undercurrent found by the ' Scotia ' 

 below the Weddell Sea, stating that it 'was a source of great trouble, and on two occasions prevented 

 the trawl from reaching the bottom, while on a third we had to pay out about 1000 extra fathoms of 

 cable before this was effected '. 



These incidents seem to have left a profound impression on Bruce's mind, for in a later chapter 

 (pp. 183-7), speculating on the possibility of a northward spread of benthic life from high latitudes 

 through the agency of a strong bottom current having its origin in the Antarctic, he writes, ' That there 

 is a strong underflowing current south of 70° S., in the vicinity of Coats Land is certain, for on three 

 occasions the " Scotia's " trawl was prevented from reaching the bottom evidently having been swept 

 [away] by such a current'. 



1 In a letter to Bruce, quoted by Rudmose Brown (1923), Sir Joseph Hooker refers to the 'almost superhuman attempts' 

 of his old commander to sound at great depths, adding that he was not surprised that now and then he should have failed. 

 Ross's deep soundings were carried out from two open boats moored fore and aft, the forward boat keeping the after, which 

 carried the sounding reel, head on to wind and sea. After the line had been run out it had to be laboriously manhandled back 

 on to the drum. 



