39 



and these can only be obtained with certainty and facility by means 

 of the dredge. This consists of a rectangular frame of iron, the 

 longer sides of which are sharpened in front and beveled outward 

 a little. Along the back of the frame holes are perforated for the 

 attachment of a fine meshed net, and to the 

 short sides handles are hinged, which may 

 be folded down in packing. There should 

 be a ring at the end of each handle, and 

 through these rings the rope may be passed 

 when the handles are raised, which will be 

 found a simple and sufficiently safe method 

 of fastening the dredge for use. A weight 

 should be attached to the rope two or three 

 feet in front of the dredge, which is useful 

 in sinking and keeping it in proper position 

 when operating in deep water. On each of 

 the longer sides of the frame there should be 

 a leather flap, attached, for the protection of 

 the net. The following are convenient di- 

 mensions for the apparatus : Frame, a, a, 20 

 inches long by 10 inches broad, of bar-iron, 

 1^ inches wide and one-fifth of an inch thick. 



Handles, h, b, each 17 inches long, of half-inch rod-iron. Bag, e, 

 three feet long, of mesh as fine as can be got, and strong twine ; 

 size of aperture rather larger than that of the frame. Rope, c, 20 to 

 200 fathoms to suit the depth of water. Weight, d, 51bs. ; an 

 iron window-weight answers the purpose, and is much cheaper 

 than lead. 



The dredge should be carefully cast mouth-downward, that the 

 tail of the net may not foul the handles or scythes. No precise 

 directions can be given as to the amount of scope of warp to be 

 let out; — about twice the depth of water is generally sufficient, but 

 this should be diminished or increased in proportion as the dredge 

 nips too hard or slides too easily over the ground, which may be 

 readily determined by feeling the rope. The dredge is liable to be 

 caught on rocky bottoms. "When the check is felt, it is usually 

 only necessary to heave in a portion of the warp, but sometimes 

 the boat must be put about and run in an opposite direction. 



All bottoms should be searched with the dredge, but gravelly 

 and shelly ground will be found most productive. The boat may 



