
ON A DEEP SHA TOW-NET, ETC. 105 
a notch with parallel sides, and a pin (0., b’.), which moves 
up and down in a hole, can pass across the notch or, 
rising up, leave it entirely free. A bell-crank lever (c.,¢’.), 
pivoted at d., d’., the extremity of which passes through a 
slot in the upper end of the pin, is the means whereby it 
is moved up and down. Upon the other end of the lever 
impinges a rod (g. g’.) which runs in a hole parallel with 
the towing rope, the head of which is a curved piece of 
brass more or less embracing the rope, of the exact shape 
and disposition of which more will be said later on. 
Suffice it for the present to point out that pressure upon 
g. in a downward direction will withdraw the pin (0.) from 
the notch. 
The screw (j.) is simply for the purpose of preventing 
the pin (g’.) from rotating on its axis. 
3. The Messengers. 
The controller of the net is able to exercise pressure 
upon the pins (g.,g’.) by means of perforated weights, 
which are allowed to slide down the rope by which the 
net is dragged. There are two of these, one for opening, 
the other for closing the net; they may be conveniently 
known as the ‘‘first’’ and ‘‘second.”’ 
1. The jirst messenger is represented in fig. 3. It is 
constructed upon the ingenious principle devised by Captain 
Rung, of the Danish Meteorological Institute,* im two 
halves, in such a manner that it can be put upon the 
rope at any point. The form of these two portions may 
perhaps be described by saying that the perforated weight 
is cut across transversely, except that a longitudinal slip, 
extending from centre to circumference, is cut out of the 
upper half and left attached to the lower, and vice versa. 
* Den tekniske Forenings Tidsskrift, 1883; see also Mill, art. ‘‘Thermo- 
meter,” Ency. Brit., 9th ed. 
