1869.] on the Scientific Exploration of the Deep Sea. 425 



gradually and uniformly reduced during its descent by the increasing 

 friction of the lengthening line. The uniformity of this retardation gives 

 an infallible test of the success of the sounding, and a certain indication of 

 the moment when the weight reaches the bottom. The latter was, how- 

 ever, valuable only for corroboration, as even at these enormous depths 

 the shock of the arrest of the weight on the bottom, nearly three miles 

 down, was distinctly perceptible to the skilled hand of our Commander. 

 As the scientific value of our results depends upon the certainty of the de- 

 termination of the depths, we subjoin a Table of the absolute rate of the de- 

 scent of the weight in this sounding, — probably the deepest hitherto made 

 which is thoroughly reliable, having been taken with the most perfect 

 appliances, and with consummate skill. 



Fathoms. 



Time. 



Interval. 



Fathoms. 



Time. 



Interval. 





h m s 



m s 





h m s 



m s 



o 



2 44 20 





1 1300 



58 5 



1 23 



IOO 



45 5 



45 



1400 



2 59 37 



1 32 



200 



45 45 



40 



1500 



3 « 9 



1 32 



300 



46 30 



45 



1600 



2 42 



1 33 



4c 0 



47 25 



55 



1700 



4 l 9 



J 37 



500 



48 15 



5° 



i8co 



6 6 



1 47 



600 



49 l S 



1 0 



1900 



7 53 



■ 47 



700 



50 24 



1 9 



) 2000 



9 4° 



■ 47 



800 



51 23 



59 



2100 



11 29 



1 49 



900 



52 45 



1 22 



2200 



13 24 



1 55 



1000 



54 0 



« 15 



2300 



15 23 



1 59 



I IOO 



55 21 



56 42 



1 21 



2400 



17 15 



1 52 



1200 



1 21 



2435 



i7 55 



40 



The whole time occupied in descent was 33 minutes 35 seconds ; and in 

 heaving up 2 hours 2 minutes. The cylinder of the sounding-apparatus 

 came up filled with fine grey Atlantic ooze, containing a considerable pro- 

 portion of fresh shells of Globigerina. The two Miller- Casella thermometers, 

 Nos. 100 and 103, attached as usual to the line above the sounding-instru- 

 ment, registered a minimum temperature of 36°'5 F. (2°'5 C). 



45. A Dredge was sent down at 5.45 p.m. ; and as this was the deepest 

 haul, the one which tested our resources most fully, and which seemed to 

 us to prove that dredging could, with sufficient care and skill, be suc- 

 cessfully carried out in any known depth in the ocean, we give here the 

 details of the operation and the appliances used. — The dredge was of 

 wrought iron, made on exactly the same plan as the " Naturalists' " dredge 

 introduced by Ball and Forbes. The two scrapers were pitched at a very 

 low angle. The arms were moveable, and about half of each arm next 

 the eye to which the rope was attached was of strong chain : we are bv no 

 means sure, however, that this was an advantage. On one side the chain 

 was attached to the arm of the dredge by a stop of five turns of spun 

 yarn, so that in case of the dredge becoming entangled, or wedged by 

 rocks or stones, a strain less than sufficient to break the dredge-rope would 

 break the stop, alter the position of the dredge, and probably enable it 



