in the Twenty Years before 1895 37 



walls, which completely prevented over heating and over cooling, 

 the splendid ventilation which was provided by the twenty-gun 

 ports on the main deck, and the practice of making the passage 

 under sail. 



A word with regard to the equipment. Throughout the 



ige hemp sounding-line and hemp dredging- rope were 

 used, and much of the success of the expedition is due to thi^ 

 fact. There was really no temptation to use anything else, 

 because wire sounding had not passed the experimental stage, 

 and all that was known for certain was that the same wire 

 could not be expected to be used in many soundings without 

 breaking. As our sounding line was on every occasion to carry 

 a load of valuable instruments, this risk could not be run. 

 Captain Nares knew that he could do all that was wanted 

 with sounding line, and he was brilliantly justified by the 

 result. There was no question of using wire rope for dredging. 

 It was first used in America by Agassiz in 1877, and on this 

 side of the Atlantic by myself in 1878. 



Wire is suitable only for sounding, pure and simple ; and the 



ltd investigation of the form of the bottom of the ocean 



cannot be carried out with anything else. As there is nothing 



ie end of the wire but a sounding tube or a sinker, it can 



be hove up as quickly as the engine will run, and the loss 



wing to a breakage of the wire is insignificant. For deep-sea 



research it is entin-lv unsuitable, because it has to carry valuable 



nnt-nN. Their value increases largely with the number 



of tim< - that they are employed, and when they arc lost, for 



instance, in the Pacific, it takes the best part of a year to 



replace th-m. and thru they are replaced by new instruments 



which have no hi>tnrv. 



The question is not infrequently asked why hemp line 



was used for evcrvtliin- in the "Challenger" expedition, and 



wire and win- rope. Although wire had already been 



used for sounding many years before, it was due to Lord 



Krlvin. then Sir Wm. Thomson, that the use of wire was 



ie practicallv available. He studied it on board his \a< hi. 



I .alia Rnnkh." and designed the apparatus necessary 



for giving it a place on -lupin. aid. and thus reduced it to 



