1911] Kofoid: Self-dosing Plankton Net. 327 



weight which can be slipped to any desired position in front-to- 

 rear direction and secured there by the set-screw above it (pi. 23, 

 fig. i.). The parts in the right-to-left plane are structurally 

 balanced in the main. The cable is passed into the position in 

 the axis of the head-piece through a narrow cable slot (c. sL, pi. 

 25, fig. 15) which is closed again by a close-fitting wedge or 

 slot filler (si. fit.) held securely in place by a pinto set screw 

 (s. scr.) whose head projects laterally slightly beyond the margin 

 of the pedestal (pi. 23, fig. 3). A stout steel cable bolt (c. h.), 

 2.5 by 24 cm., is passed from the side of the pedestal through the 

 eye of the cable and secured in place by a winged thumb-bolt 

 {th. 1)}). The end of the cable bolt bears a circular opening 

 (op.) for withdrawing it, when the thumb-bolt is released. 

 "When the bolt is free of the cable the thumb-bolt falls in the 

 second position (/A. h.-) after the fashion of a door bolt, and the 

 cable bolt cannot be entirely withdrawn. 



THE CLOSING MECHANISM 



The closing mechanism consists of the two hinged jaws at the 

 mouth of the net which swing forwards and downwards, the 

 tripping apparatus in the head-piece, and the two messengers 

 which open and close the net. The two hinged jaws (pi. 24, 

 fig. 5) are semicircular phosphor-bronze castings which together 

 complete a circle 37 cm. in inside diameter. Upon either side, 

 each passes into a cylindrical hub (huh., pi. 24, fig. 6, see also 

 figures 5 and 10) 82 mm. long and 82 mm. in diameter. Each 

 hub consists of three main regions, two of which (2 and 3) are 

 structurally parts of the jaws; (1) the central axle (ax., pi. 24, 

 fig. 5), (2) the inner cylinder (/». cyl.), and (3) the outer 

 cylinder (out. cyl.). 



The central axis consists of a shaft 82 mm. long and 25 mm. in 

 diameter whose inner end is bored and threaded for the screw 

 (sc.) which holds the fixed pulley (pul.) against the inner face 

 of the jaws and holds the axle (ax.) within the inner cylinder 

 (in. cyl.). The outer end of the axle is a cjdindrical head (hd.) 

 27 mm. long and 50 mm. in diameter with a cubical socket (sock., 

 pi. 24, figs. 5, 6 and 9) in the axis, ]7mm. square and 8 mm. 



