150 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Guide rings for drawstring, six in nnuiber, of brass i-g-incb wire and 1 inch diam- 
eter, are secured to the outer net at equal distances around its surface, 2 inches below 
the drawstring blocks. They are so placed, in order to give sufficient slack in the 
upper ijortiou of the net to allow it to close without bringing iindue tension on the 
web. 
The drawstring, 13 feet long, is a braided cord ^ inch diameter, used to close the 
net after towing, and before hoisting it to the surface. Cod line or any other material 
of the proper size would answer the purpose, but the braided cord was selected as less 
liable to kink while hanging loosely during the process of lowering and towing; it 
presents a smooth surface to the net, and reduces to a minimum the wear on the web 
caused by repeated opening, closing, towing, and hoisting. 
Tripping hues, two in number, are of cod line, barked, 9 feet 6 inches long, with a 
7-inch loop or eye on the upper end. Any material of iiroper size may be used. 
To assemble the apparatus . — The ring being intact, Avith the arms lying side by side 
across it, their lower ends attached to their respective tees, raise the arms and shackle 
the sinker in place. Shackle the tow line, or dredge rope, to the other end of the 
sinker, and susiiend the ring at a com^enient height ; screw the legs into their respec- 
tive sockets, which will be recognized by marks of a center punch, thus -h-h 
: : : ; then place the apron in position and seciire it by the screw bolts. The movable 
weights should not be remoA^ed from their legs, 4 - and : . : : . 
Seize the net to tlie ring, take one turn of the drawstring around the body of the 
net through the rings, middle it, and take an overhand knot in it; then pass each end 
outward through a ring, reerm them through the lower blocks, then through the upper 
blocks, ami hitch to the moAmble weight through the holes in the lugs provided for the 
purpose. 
Hitch the ends of the tripping lines through the other holes in the lugs, place the 
friction clamp on the rope, slip the loops over the lip of the tumbler, and slide the 
clamp up the rope until theAveights are suspended about 4 inches below the ring; then 
with the wrench provided for the purpose, tighten the adjusting screw, keeping the 
tumbler elevated and pressed against the rope until the clamp grips it with sufficient 
force to hold it in place. ITaving once ascertained the proper place for the clamp by 
measurement it can thereafter be secured at the same joint without further attention 
to the tripiAing lines, which may be hooked in place anrl the Aveights suspended as 
desired by simply taking in a trifle more or less at the hitch. 
The length of tripping lines, 9 feet 0 inches, Avas intended to give sufficient drift 
for the weights to close the net eA^en if the tumbler failed to capsize or the loops to 
unhook from it. A single weight will securely close the net if from any cause the other 
fails to act. 
To use the net . — Having assembled the parts as directed, and attached the tow 
line, overhaul the drawstring until the net hangs entirely free from stricture; then 
swing the apparatus out, taking care that it does not come in contact with the ship's 
side. Bring the A^essel to a dead stop, and loAver away about 25 fathoms a minute, 
until the required depth is reached ; then move slowly ahead, veering gently on the 
tow rope until enough has been paid out to maintain the net at the proper depth. 
This can be done with sufficient accuracy by observing the angle of the tow line from 
the vertical, and, after making allowance for the catenary, using the angle and 
length of rope out as the hypotheuuse of a right-angle triangle, the depth represent- 
