20 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [18] 



composed of six strands laid around a hemp heart, each strand com- 

 posed of seven galvanized steel wires (No. 19 American gauge) having 

 no hemp heart. 



Sigsbee — "Deep-sea dredging and trawling" — gives the ultimate 

 strength of the rope as 8,750 pounds, and the breaking strain, in kinks, 

 4,500 jjounds ; weight, 1.14 pounds per fathom in air, or about one pound 

 in sea-water. 



PREPARATION FOR DREDGING. 



The rope being on the reel the end is passed between the rollers of 

 the automatic guide (Plate V), carried aloft and rove through the 

 block on the lower end of the accumulator (Plate IX), brought down 

 again and rove under the registering sheave in the heal of the boom, 

 thence through the dredging block at the boom end, and spliced into 

 the eye of the safety-hooks. 



The boom is then topped up and secured over the side port by strong 

 fore-and-aft guys, the trawl shackled to the safety-hooks and swayed 

 up clear of the rail, a man at each end to steady it, an engineer at the 

 hoisting engine, and the officer in charge, as shown in Plate IX, ready 

 at the order to lower away. 



TRAWLS. 



The beam trawl, shown in Plate IX, is used by the Commission, 

 and, for moderate depths, has not been equaled by any other form. 

 Three sizes are used, the smallest with 9 feet length of beam, the second 

 with 11 feet, and the third 17 feet, the length of net from 15 feet to 40 

 feet. The trawl nets are invariably provided with pockets. 



The Otter trawl has been used to advantage in shoal water, over 

 smooth bottom, when the capture offish was the special object. 



It is necessary for the successful operation of the beam trawl that it 

 should land right side up. A capsize in moderate depths is rare, but 

 in deep water it may be considered as among the probabilities. 



To avoid the vexatious delays attending accidents of this nature, 

 Professor Agassiz and the officers of the Blake devised a double trawl 

 which works equally well either side up and was subsequently used on 

 board that vessel with excellent results. It has also been used experi- 

 mentally by the vessels of the Commission, but they have not heretofore 

 operated in sufficient depths to make it a necessity. 



DREDGES. 



The common form of deep-sea dredge is used by the Commission, with 

 excellent results on sandy bottoms. The form designed by the officers 

 !)f the Blake, and used successfully on board that vessel, is adapted for 

 very soft bottoms usually encountered at great depths. 



THE CHESTER RAKE DREDGE. 



This arrangement of a double rake to be used in connection with a 

 dredge of any form is shown in Plate X and is very useful in bringing 



