292 DREDGING AND TRAWLING 



were very highly spoken of by the naturalists on the 

 " Challenger," but in recent years they have not been 

 much employed. 



The dredge should be attached to the warp in the 

 following way : The eye at the end of one of the bridles 

 is secured to the eye at the end of the warp by means of 

 a screw shackle, and the other eye is made fast merely 

 by a strong strop or lashing of trawl- twine. This 

 arrangement is invaluable in the event of the dredge 

 becoming fast among rocks, for in that case the lashing 

 parts and the frame is drawn along sideways, thus 

 usually clearing the obstruction and preserving the 

 dredge from injury. 



In 50 fathoms of water or less it is usually best to 

 pay out warp to the extent of two or three times the 

 depth ; in deeper water less is required, and when 

 working in soundings of 1,000 fathoms or more, 400 or 

 500 fathoms in excess of the depth will be found 

 sufficient. In many localities, however, the nature of 

 the bottom is so extremely rough that, if this amount 

 of warp is given, the strop parts on every occasion. 

 On such grounds it is advisable to pay out only a little 

 warp in excess of the depth, and, after the ship has been 

 stopped, to ascertain if the dredge is biting by holding 

 the warp.* More warp may then be given cautiously 

 if required. 



Shooting and Towing. 



Sailing Yachts. Always tow with the tide if possible. 

 With a moderate amount of way on the boat throw the 

 dredge over on the windward quarter, and pay out a 

 sufficient length of warp. Make the warp fast with 

 a stop of small rope, but be sure to have the end well 



* By holding the warp it is often possible to feel a heavy 

 dredge working, even at depths of 500 fathoms. 



