THE DREDGE 291 



other is made of sacking or stout canvas, and preserves 

 a sample of the sand or other fine bottom material. 



The two main bags — of trawl-twine and sprat 

 netting — are lashed to rings at the back of the dredge, 

 or they may be fastened directly to the frame by means 

 of seizing wire. Each bag is opened or closed behind 

 by means of a running string through the meshes. 

 The small bags are stitched in position through both 

 the main bags, and their ends are secured by a lashing. 



The nets for small frames for use in shallow water 

 are generally of a simple pattern. For these a piece of 

 the cod end of a shrimp-trawl or the extra stout sprat 

 netting mentioned above is suitable, with or without 

 a lining of mosquito netting. 



For the conical dredge a strong canvas bag is recom- 

 mended. Dredges used in deep water should always 

 have a piece of chain fastened to the end of the bag to 

 prevent it getting foul of the frame while being lowered 

 to the bottom, and this device is also useful at all depths 

 when the net is new. 



A tow net made of cheese-cloth, with a strong cane 

 ring, is sometimes fastened to the dredge. It is usually 

 attached to the shackle at the end of the warp, with a 

 strop sufficiently long to allow it to lie with its mouth 

 a little behind the frame. By this arrangement the 

 tow net is designed to catch the small animals dis- 

 turbed by the swords of the dredge. This method has 

 been known to produce the most satisfactory results, 

 but the safe recovery of the tow net is decidedly 

 uncertain. 



Tangles (or swabs) consist of lengths of hemp rope 

 teased out, and fastened to the end of the bag or to 

 an iron rod attached by chains to the frame. Starfish 

 and other animals become entangled in the threads of 

 the hemp, and are thus drawn to the surface. Tangles 



