Nets were originally used on the shore. A long strip of netting was attached to upright stakes, to form an enclosure with an opening towards the sea, constructed like a fishing weir in such a way that the fish enter the enclosure at high tide and are unable to escape. Such devices constructed on shore are known as “fixed engines”; they include stake nets, poke nets, stream nets and purse nets. The net may simply form the wall of an enclosure (stake net). This enclosure may be furnished with a pocket at one corner (poke net). It may consist essentially of one long, deep pocket kept open by rings or stakes at intervals (purse and hose nets). It may be simply a wall of netting into which the fish thrust their heads; owing to their gill openings they are unable to withdraw and so become entangled (stream net). The first development of a movable net was the seine or drag net. The seine is a semi-circular drag net, which is shot in shallow water so as to enclose an area of water close to the shore. It is then hauled ashore, and gathers up the fish that are in the enclosed area of water. Such a net is limited to inshore use. Generally, a line is attached to each end of the net. The free end of one of these lines is made fast to the shore by a stake, and the net is paid out from a small boat. When the whole of the net has been paid out, the boat travels round until the net forms a semi-circle of which the diameter is parallel to the shore; the net is then hauled in. The seine net was used in ancient times by Phoenicians, Greeks, and other Mediterranean peoples. Various types of seines are in common use to-day. In Denmark a seine net is employed to catch eels and plaice. On the Cornish coast pilchards are caught with a large seine up to two hundred fathoms long and eight fathoms deep. In the United States a seine is used in water of any depth to catch mackerel. Rings are attached to the foot-rope of the net, and by passing a line through these rings and drawing it tight, the net is transformed into a bowl of netting. This is called the purse seine. [Illustration: FIG. 9 TRAWLING (_circa_ 1750)] The seine was first improved by the addition of a pocket at its centre. Then the sides or wings were gradually lengthened, until finally it developed into a deep, conical, bag-shaped net, furnished with long arms or wings. This was dragged along the bottom, behind a boat in full sail. The net was weighted and its mouth kept open by attaching its upper edge to a beam of wood (beam trawl). When the net was full of fish, it was run ashore. Ultimately, instead of drawing the net ashore, the fishermen remained at sea and hauled the net on board with a winch. In this way the seine net gradually developed into the trawl net. The trawl net marked a big improvement, for it could be fished in deeper water further from shore, and thus greatly increased the scope of fishing operations, and led to the rapid growth and improvement of demersal fishing.