ON A DEEP SEA TOW-NET, ETC. 107 
by which the two halves can be secured from any risk of 
coming apart during the descent, will be added. 
MopeE oF WORKING. 
The apparatus itself having been described, a few 
paragraphs may now be devoted to explaining the manner 
in which it is used. It is designed to act either at the 
end of a special rope or when attached at any point of a 
rope which is being used either for dredging or trawling. 
In this latter case it is of great advantage that a wire rope 
should be used, as its less flexibility makes the descent 
of the messengers full upon the heads of the pins more 
certain. 
In fig. 1 the arrangement is shown when a special rope 
for the tow-net is used. This is passed through the 
channel between the two cheeks of the lock and made 
secure by means of the bolts. To itsend a lead is attached, 
the weight of which depends upon the size of the net, the 
depth it is desired to reach and the speed of the vessel. 
The loop (j.) on the closing line is now placed in the 
notch on the nearer side of the instrument in fig. 6, and 
the pin (b’.) is pressed down through it. The loop (e.) on 
the opening line is similarly placed in the other notch and 
the pin (J.) passed through it. In this position of affairs, 
as explained above, the resistance of the net as it is 
dragged through the water will keep it shut. 
A small lead of four or five pounds weight is attached to 
the lower margin of the net (fig. 1), and it is then carefully 
let down over the stern of the vessel whilst under weigh, 
care being taken to see that it is shut and that the 
weighted side is downwards. All being clear, the two 
series of links are payed out and lastly the lock and sinker. 
A fair amount of way (four to five knots) should be kept 
on the vessel whilst this is being done, and enough rope 
