2go DREDGING AND TRAWLING 



ioo fathoms patterns from 3 feet to 3 feet 6 inches long 

 and 8 to 9 inches broad are useful, while for very great 

 depths large heavy makes up to 5 feet long and 1 foot 

 broad are recommended. 



The term naturalist's dredge may be restricted to a 

 form of frame which differs from the foregoing only 

 in the absence of swords. The effect of this is that the 

 straight edge of the frame tends to skim the surface 

 of the ground instead of biting into it.. This type has 

 been almost entirely superseded by that mentioned 

 above. 



The conical dredge is designed to dig into the soil ; of 

 this it brings up a good sample, together with specimens 

 of burrowing animals. 



The bag or net which is fastened to the dredge should 

 be quite as long as, if not longer than, the frame, and 

 should not be tapered behind. It may be made of 

 strong manila trawl-twine of 2-inch mesh,* but a most 

 suitable bag may be constructed from the cod end of an 

 old trawl ; this is usually easily procured and fitted. 

 Loose chafing pieces attached to the outside are very 

 useful, and save a great deal of wear and tear. For 

 catching small animals and for use on smooth ground, 

 a lining of sprat netting of i-inch mesh, or even finer, 

 may be fitted inside the bag (some firms stock an extra 

 stout make of sprat netting, which is excellent for this 

 purpose). The lining should be made fully as large as 

 the outer bag, so that the strain is taken up by the 

 latter. 



Two small bags may also be fitted in the tail end of 

 the lining ; one of these is made of shrimp netting, and 

 is designed to catch some of the smaller organisms 

 which would pass through the i-inch mesh, while the 



* Meshes are measured diagonally when the net is stretched 

 out ; thus 2-inch mesh means openings of 1 square inch, 



