454 THE POPULAR SCIENCE MONTHLY. 



upward of eight statute miles," with a hundred-weight and a half of 

 solid contents. 



The trawl is a sort of net for catching those fish which habitually- 

 live at the bottom of the sea, such as soles, plaice, turbot, and gurnett. 

 The mouth of the net may be thirty or forty feet wide, and one edge 

 of its mouth is fastened to a beam of wood of the same length. The 

 two ends of the beam are supported by curved pieces of iron, which 

 raise the beam and the edge of the net which is fastened to it, for a 

 short distance, while the other edge of the mouth of the net trails upon 

 the ground. The closed end of the net has the form of a great pouch ; 

 and, as the beam is dragged along, the fish, roused from the bottom 

 by the sweeping of the net, readily pass into its mouth and accumu- 

 late in the pouch at its end. After drifting with the tide for six or 

 seven hours the trawl is hauled up, the marketable fish are picked 

 out, the others thrown away, and the trawl sent overboard for another 

 operation. 



More than a thousand sail of well-found trawlers are constantly 

 engaged in sweeping the seas around our coast in this way, and it is 

 to them that we owe a very large proportion of our supply of fish. 

 The difficulty of trawling, like that of dredging, rapidly increases with 

 the depth at which the operation is performed ; and, until the other 

 day, it is probable that trawling at so great a depth as 100 fathoms 

 was something unheard of. But the first news from the Challenger 

 opens up new possibilities for the trawl. 



Dr. Wyville Thomson writes (Nature, March 20, 1873) : 



" For the first two or three hauls in very deep water off the coast of Port- 

 ugal, the dredge came up filled with the usual 'Atlantic ooze,' tenacious and 

 uniform throughout, and the work of hours, in sifting, gave the very smallest 

 possible result. "We were extremely anxious to get some idea of the general 

 character of the Fauna, and particularly of the distribution of the higher 

 groups ; and, after various suggestions for modification of the dredge, it was 

 proposed to try the ordinary trawl. "We had a compact trawl, with a 15-feet 

 beam, on hoard, and we sent it down off Cape St. Vincent at a depth of 600 

 fatboms. The experiment looked hazardous, hut, to our great satisfaction, the 

 trawl came up all right, and contained, with many of the larger invertebrata, 

 several fishes. . . . After the first attempt we tried the trawl several times at 

 depths of 1,090, 1,525, and, finally, 2,125 fathoms, and always with success." 



To the coral-fishers of the Mediterranean, who seek the precious 

 red coral, which grows firmly fixed to rocks at a depth of sixty to 

 eighty fathoms, both the dredge and the trawl would be useless. 

 Thev, therefore, have recourse to a sort of frame, to which are fastened 

 long bundles of loosely-netted hempen cord, and which is lowered by 

 a rope to the depth at which the hempen cords can sweep over the 

 surface of the rocks and break off the coral, which is brought up en- 

 tangled in the cords. A similar contrivance has arisen out of the 

 necessities of deep-sea exploration. 



