CHAP, i.] INTRODUCTION. 3 



mine with precision the composition and temperature 

 of sea-water at great depths. An investigation of this 

 kind is beyond the ordinary limits of private enter- 

 prise. It requires more power and sea skill than 

 naturalists can usually command. -When, however, 

 in the year 1868, at the instance of my colleague 

 Dr. Carpenter and myself, with the effective support 

 of the present Hydrographer to the Navy, w r ho is 

 deeply interested in the scientific aspects of his pro- 

 fession, we had placed at our disposal by the Admi- 

 ralty sufficient power and skill to make the experiment, 

 we found that we could work, not with so much ease, 

 but with as much certainty, at a depth of 600 fathoms 

 as at 100 ; and in 1869 we carried the operations down 

 to 2,435 fathoms, 14,610 feet, nearly three statute 

 miles, with perfect success. 



Dredging in such deep water was doubtless very 

 trying, Each haul occupied seven or eight hours ; 

 and during the whole of that time it demanded and 

 received the most anxious care on the part of our 

 commander, who stood with his hand on the pulse of 

 the accumulator ready at any moment, by a turn of 

 the paddles, to ease any undue strain. The men, 

 stimulated and encouraged by the cordial interest 

 taken by their officers in our operations, worked 

 willingly and well ; but the labour of taking upwards 

 of three miles of rope coming up with a heavy strain, 

 from the surging drum of the engine, was very severe. 

 The rope itself, 'hawser-laid/ of the best Italian 

 hemp, 2ijr inches in circumference, with a breaking 

 strain of 2^- tons, looked frayed out and worn, as if it 

 could not have been trusted to stand this extraordinary 

 ordeal much longer. 



B 2 



