DEED-SEA DREDGING. The methods employed on board the United States Fish Commission steamship _I thatross, doubtless the best-equipped deep-sea dredger in existence, may be taken as illustrative. The Albatross has brought together larger deep-sea collections than have been made on any other vessel. She has made nearly 6000 hydrographie soundings, and nearly 2000 hauls of the dredge or beam trawl. The investigations of this vessel cover areas extending from the Banks of Newfoundland both coasts of North and South America to Bering Sea, and also limited areas in the tropical Pacific, and in the regions between Japan and Kamchatka. 'Ter work has carried dredging into deeper waters than ever before, animal life having been obtained near the Tonga Islands at a depth of 4173 fath oms, while the dredge on one occasion in Bering Sea brought up from a depth of 1771 fathoms more than SOD deep-sea fishes at a single haul.
The creatures of the deep sea are brought up by means of a dredge or beam trawl towed by a wire rope, operated by a powerful engine on deck. The first operation in dredging is to ascertain the depth by sounding, after which the trawl is put overboard and allowed to sink to the bottom as the dredge rope is let out. The dredge, or beam trawl, is simply an iron frame to which is at tached a strong bag-shaped net about 20 feet long. The mouth of the dredge, as formed by the iron frame, is about eleven feet wide and two feet high. Dragged along the bottom, it quickly fills with animal:. Sometimes it settles into mud or ooze and is very hard to lift. The dredge
rope is connected with a large spring, or accu mulator, attached to the foremast, which often shows the dredge to be pulling thousands of pounds. Before the dredge reaches the surface, most of the oozy mud washes away. so that the dredge haul is usually light enough to he hoisted from the water and landed on deck with safety. Sometimes it is filled with fishes; sometimes with sea-urchins, starfishes. erinoids or corals: sometimes with squids and devil-fish. It often brings up a varied collection. in which many classes of marine animals are represented. The time required by the Albatross in making her deepest dredge haul—that from 4173 fathoms— was ten hours, the engine reeling in the great weight of line very slowly. In depths of 1000 to 1500 fathoms hauls can be made in three or four hours, according to conditions.
In addition to the dredge, another collecting machine, very useful on rough bottom, is the 'tangle.' This consists of bunches of shredded rope attached to iron bars, and when dragged over the bottom it frequently brings up sea urchins, starfish, and erinoids in abundance. A deep-sea fish-trap has been devised by the Prince of Monaco, in which fishes have been taken as deep as two miles. The Alba tross. in 1597, suc ceeded in setting ordinary gill-nets a mile deep. and catching Macrurus and other deep-water fishes. Deep-water exploration by means of gill nets. traps, and trawl lines promises to yield interesting results.