1903.] on Some Problems and Methods of Oceanic Research. 373 



was made with a sinker weighing 336 lbs. The " Baillie " tube 

 which carried it weighed 25 lbs., and the water bottle weighed 20 lbs., 

 so that the total weight at the end of the line was 381 lbs. in air. 

 Excepting the water bottle which was of bronze, all this weight was 

 of iron, and we find its weight in water by deducting one-eighth or 

 48 lbs. which leaves 333 lbs. as the effective sinking weight. The 

 No. 1 line, which v/as in daily use, weighed in water 6 lbs. per 100 

 fathoms (in air it weighed 20 lbs.). Therefore, every 100 fathoms 

 of line used in the sounding added 6 lbs. to the effective sinking 

 weight, but at the same time by its friction it produced a retardation 

 which depended on the velocity of descent. The retarding effect, 

 except in very shallow water, is greater than the accelerating effect, 

 therefore the net effect is one of retardation. With wire the opposite 

 is the case. After the first 50 or 100 fathoms of line have run out, 

 there is a continual and progressive retardation. The line was always 

 allowed to run out free from coils on the deck and without any break 

 or resistance. 



Perhaps the greatest advantage which hemp line has over wire 

 for sounding, and more particularly for dredging in deep water, is 

 that it loses about 70 per cent, of its weight when immersed in water, 

 whereas the wire loses only 13 J per cent. Thus, the No. 1 line 

 weighs in air 200 lbs. per thousand fathoms and only 60 lbs. in 

 water. The same length of sounding wire weighs 14^ lbs. in air 

 and 12*6 lbs. in water. The breaking strain of the line is 14 cwt. 

 or 1568 lbs., that of the wire is 210 lbs. The length of the line 

 which weighs 1568 lbs. in water is 26,000 fathoms, while that of the 

 wire which weighs 210 lbs. in water is 16,700 fathoms. Therefore, 

 granting that we can sound in 16,700 fathoms with wire, there are 

 nearly 10,000 fathoms more that can be explored only with hemp, 

 and beyond 26,000 fathoms, if such depths existed, we should not be 

 able to explore them at all. 



Of course these limiting depths are purely theoretical, because, 

 each being at its breaking strain, neither the line nor the wire could 

 be hove up from them. They serve, however, to accentuate a very 

 real advantage which the hemp line has over the metal wire. This 

 advantage will make itself practically felt in dredging in the great 

 depths of 4000 and even 5000 fathoms which are now known to 

 exist. For instance, the wire rope used by Agassiz on board the 

 Blake had a circumference of 1^ inch. One fathom of it weighed 

 1*14 lb. in air and 1 lb. in water. Its breaking strain was 8750 lbs., 

 so that its hreaJcing length was 8750 fathoms in water and at rest. 

 It is obvious that if it were to be used for dredging in 5000 fathoms 

 the remaining 3750 lbs. would be quite inadequate to bear the weight 

 of the dredge with its contents, and the strain which would have to 

 be exerted in order to bring it up in a reasonable time, to say nothing 

 of the margin for safety, or of the resistance while being dragged over 

 the ground. 



Much misunderstanding prevails about the relative rapidity with 



