18 THE EXPLORATION OF THE SEA [PART I 



and the beam is about two feet from the ground. Behind the 

 beam and fastened to it and the irons is the ''headline/' and 

 connecting the lower parts of the irons is the " foot-rope," a rope 

 which is about three inches in diameter, which is often weighted 

 with iron chain, and which drags on the sea bottom, forming a 

 wide bight behind the beam. To the foot-rope and headline is 

 " bent " the trawl net. This is a long conical bag of strong 

 netting, the mesh of which varies with the size and nature of 

 the animals which the trawl is designed to catch. The length of 

 the net varies but it is always one and a half times or more than 

 the length of the beam. About half-way between the foot-rope 

 and the end, or " cod end " of the net, are two folds of netting 

 attached to the back and belly of the trawl net and inclined 

 backwards towards the middle line of the latter but not meeting. 

 These are the "pockets," and they form a funnel-shaped trap 

 through which the animals caught by the net pass into the tail 

 and through which they find difficulty in passing out again on 

 account of the eddies caused within the net by the water which 

 does not pass through the meshes. The cod end is open but is 

 laced by a rope when the net is put down. From each of the 

 irons a strong rope, the " bridle," passes forward and the ends of 

 the bridles are " shackled " on to the trawl warp or rope. 



In the largest trawls used by fishing steamers the beam is 

 discarded and the ends of the net are kept apart by two " otter 

 boards," which are heavy wooden framed boards shod with iron 

 and about the size of an ordinary house door. To these the 

 headline and foot-rope are attached. The otter boards are so 

 fastened to the two separate trawl warps, by means of which 

 the trawl is towed, that they are inclined at an angle to the 

 direction of tow of the apparatus, and thus the mouth of the 

 net is kept open. In the largest otter trawls the length of the 

 headline may be as much as 100 feet, the foot-rope being half as 

 much again. 



For scientific fishing, that is fishing with a scientific object, 

 a " shrimp trawl " is usually more suitable than the ordinary wide 

 meshed fish trawl. In the latter the meshes are usually about 

 one to one and a half inches from knot to knot, while in the 

 shrimp net the distance is only about half an inch. Otherwise 



