EQUIPMENT. 



31 



when there is a ^eat weight in it, or when the vessel is pitching. 

 The curve made by the wire rope, as it leads from the vessel 

 to the trawl, is of itself the best accimiulator, as a com- 

 paratively slight strain will constantly tend to change 

 the form of the catenary. It is only while hoisting 

 the dredge that the accumulator is useful, and long 

 before it works to its fidl power the changes of form 

 of the catenary of the wire rope, from an easy winding 

 in of the dredge to the fouling of the same, will pro- 

 duce a greater or less strain, entirely unnoticed, on the 

 accumulator, if (as in our case) the strain is less than 

 two thousand pounds. The friction of the steel rope 

 asrainst the wire, even when two or three thousand 

 fathoms of wire are out, is far less than the breaking 

 weight (eighty-six hundred pounds) of the steel-wire 

 rope (one and one eighth inches circumference) used 

 on the " Blake." 



The steel rope was hoisted by a small double-cylin- 

 der windinof-enofine, with a sursfinof-drum, from which 

 the rope then passed to the reel, where it was coiled 

 as closely as practicable. The reel was managed by 

 a pair of small engines used to wind the line, and by 

 a friction-brake when the rope was lowered. 



In dredging, the dredge or trawl was invariably 

 lowered independently of the winding-engine, from 

 a reel built especially for the work. This reel, built 

 of iron, consisted of a hollow axle two feet in diam- 

 eter, four feet long, flanked by flanges extending 

 eighteen inches above it, capable of winding about 

 four thousand fathoms of one and one eighth inches Fig-. 28.— Ac- 

 steel-wire rope. The axle upon which the reel ran (s^g^jgeT 

 was supported upon bearings carried upon a strong 

 iron frame securely bolted to the deck ; the reel was checked 

 by a band friction-brake, by which one man could readily con- 

 trol the velocity of the steel rope as it was unwound and could 

 accurately regulate the speed. The brake was of sufficient 

 strength to stop the dredge even at a depth of nearly two 

 thousand fathoms; and while dredging or trawling, the brake 



