October 24, 1884.] 



SCIENCE. 



401 





the interests of the small-boat dredger ; nor 

 can this material be used to advantage without 

 the aid of steam, but the active competition 

 now existing with regard to deep-sea explora- 

 tions must needs render its adoption necessary 

 by all large expeditions. 



Hemp rope was employed in all deep-sea 

 dredgings up to the winter of 1877-78. One 

 of the most serious objections to its use is the 

 amount of space it occupies, especially when, 

 as in the case of the Challenger, twenty-five 

 thousand fathoms are carried. On the Por- 

 cupine, only three thousand fathoms of two- 

 and-a-half and two-inch rope, weighing about 

 fifty-five hundred pounds, were supplied ; but 

 for the convenient storage and handling of 

 this there was required a row of twenty great 

 iron pins, about two-and-a-half feet in length, 

 projecting over one side of the quarter-deck 

 from the top of the bulwark. 



But a far greater objection to hemp-rope is 

 the length of time required in making a deep- 

 sea dredging with it, as experi- 

 enced by Sir Wyville Thomson, 

 and all other deep-sea dredgers 

 prior to the past few years. In 

 1869 the Porcupine dredged in the 

 Bay of Biscay, in a depth of 2,435 

 fathoms, requiring some ten hours 

 for one haul. On the Chal- 

 lenger an entire day would be con- 

 sumed in dredging or trawling in 

 depths of from two thousand to 

 twent} T -five hundred fathoms. 



For the utilization of steel-wire rope for 

 deep-sea dredging, we are indebted to the 

 fortunate suggestion of Professor Alexander 

 Agassiz, who first recommended its use ; and 

 to Commander Sigsbee, U.S.N., who prac- 

 tically demonstrated its superiority over all 

 other kinds of dredging-rope, and perfected the 

 method of handling it. The first trials were 

 made on the coast-surve}* steamer Blake, 

 dredging in the Gulf of Mexico, in the winter 

 of 1877-78. The size of rope then selected, 

 and since employed by both the coast survey 

 and fish commission, measures only 1| inches 1 

 in circumference, and has an ultimate strength 

 of 8,750 lbs. The chief advantages of wire 

 rope, in the words of Mr. Sigsbee, are " com- 

 pactness, strength, durability, neatness, facil- 

 ity of handling with a small force, celerity of 

 operations, and economy." The entire amount 

 required to make the deepest dredging can be 

 stored upon a single drum which occupies but 

 an inconspicuous position on the deck. But 



few men are required for the operations of 

 dredging ; and the reeling-in can be performed, 

 in case of necesshVy, by two men only, one stand- 

 ing at the hoisting-engine, the other at the reel. 



Where the dredgings are confined to depths 

 less than a thousand fathoms, as was the case 

 with the steamer Fish Hawk, the hoisting- 

 engine may be dispensed with, and the rope 

 led directly to the reel, which can be made 

 sufficiently strong to withstand the strain put 

 upon it in using so small a quantity of rope. 

 With operations simplified to this extent, a 

 single man can control both the lowering and 

 the reeling-in ; the additional help being re- 

 quired only to handle the dredging apparatus 

 on the deck, and to start it on its downward 

 passage. 



As to economy of time, the wire rope has a 

 decided advantage over hemp or manila. Sir 

 Wyville Thomson states that 



" There can be no doubt that in any future expe- 

 dition, on whatever scale, it would be an unjustifiable 



I SB imp \ f 2'iHemp j f 23akmp j 



One- of 1 



jfg inches has also been successfully tried. 



Fig. 1. — Comparative size of dredge-ropes. 

 (From Sigsbee's ' Deep-sea sounding.') 



waste of time and space to neglect the use of wire 

 for sounding, and wire rope for dredging and trawl- 

 ing ; but it seems to me that even the use of these 

 should be simplified, and not made more complex." 



Prof. IT. N. Moseley has been even more 

 generous in his acknowledgments ; and in a 

 lecture on deep-sea dredging, delivered before 

 the Royal institution of London in 1880, and 

 published in Nature for April 8 of the same 

 year, he spoke of the advantages of wire rope, 

 which have alreadv been alluded to. 



Accessories to -wire rope. 



Among the important accessories to the use 

 of wire dredge-rope, which have been intro- 

 duced in this countiy, ma}' be mentioned an 

 improved form of accumulator, a set of safety- 

 hooks for attaching the trawls, and several pat- 

 terns of dredging-blocks. 



The Sigsbee accumulator (fig. 3), which re- 

 places the pattern formerly employed by the 

 English, and which has since been adopted on 

 the French steamer Talisman, was first used 



