Introductory 



Faeroe Islands to Madeira, the Azores, and the Straits of Gibraltar, the 

 bearing of which upon modern theories of the circulation of Atlantic 

 waters will be better dealt with later on. 



For the purpose of scientific investigations of this kind, a brief 

 description of the appliances necessary may be given. 



1. Water-bottles for the collection of samples of sea- water at 

 different depths. It matters little what form of bottle is used, pro- 

 vided only that the apparatus can be guaranteed to collect the sample 

 of water from a given area without admixture of water from any layer 

 above or below. On board the Challenger the apparatus in use was 

 the bottle devised by Buchanan, and which, notwithstanding ' improved ' 

 forms of apparatus, is still quite sufficiently accurate for the purpose. 

 This is the form of ' bottle ' which has been constantly used on board 

 the Silver Belle. When the work was first undertaken in the Faeroe 

 Channel, Mills' water-bottle was used, and this is sufficiently useful 

 for moderate depths. Buchanan's bottle, which is a larger apparatus, 

 carries a reversing thermometer on a frame attached to the cylinder. 

 It is lowered and raised on a wire reeled off a drum which carries 

 2,000 fathoms, and the hauling on board the drum, which is fixed on 

 a specially-made winch, is actuated by steam, as hand-hauling at such 

 depths would not be practicable. The water-bottles of Pettersson- 

 Nansen are much more elaborate, consisting of concentric tubes, with 

 the thermometer inside the tubes. In a new pattern, the outside 

 frame carries a reversing thermometer, ' which may be used instead 

 of the deep-sea thermometer, or as a check on the results obtained 

 thereby. 1 That the use of thermometers inside the lid of the water- 

 bottle is not considered absolutely essential by the International 

 Council is indicated by the remarks of Helland Hansen in the same 

 report : 2 ' On account of faults in the manufacture three of them ' — 

 i.e., Nansen-Richter thermometers — ' were broken during the August 

 cruise, so that at some stations we were obliged to use good ordinary 

 thermometers (with milk-glass scale), which were put into the water- 

 bottle after it had come up on deck. As the temperature of the air 

 1 Robertson, ' North Sea Investigations," p. 54. 2 Ibid,, p. 3. 



