OwEN_, on the Surface-fauna of Mid-ocean. 117 
will thus be separated from the finer portions ; by decanting 
each part so obtained the heavier will be separated from the 
lighter ; thus^ four divisions well adapted for examination will 
be in separate vessels. Each haul being thus treated, a re- 
gister may be kept in bottles and on glasses of every portion 
of the ocean passed over. 
Weak spirit, or a solution of bay salt and arsenic, will pre- 
serve things in a wet state ; others may be allowed to dry on 
the glass slides. 
Larger nets may be made on a similar principle for quiet 
sailing and finer weather. Nets with large openings, a yard 
wide, may be used in calms, and from boats. A bent cane and 
a straight deal lath make a very good mouth. The material 
nearest the opening should be of fine net ; below this muslin 
should be used, and at the bottom the fine close calico bag, 
made open, and tied when used. A bag of coarse net should 
be attached to the mouth, penetrating it a yard or so, to in- 
tercept the larger things that may get into it. 
To use these nets conveniently, a spar or bamboo should 
be rigged out on the quarter or side of the vessel, having a 
guy or two to support and steady it ; a pulley or small block 
should be fastened at the outer end, through which the towing- 
line may pass and come in board some distance forward of 
the place from which the spar is projecting ; this will relieve 
the spar, in a great measure, from the strain. 
It would be found difficult to haul in such a net when the 
vessel is going ten knots an hour, but this difficulty is 
entirely removed by having a second thinner line attached 
to the side of the mouth of the net ; by hauling on this the 
strain of the water is at once taken off and the net brought 
in board with the greatest ease, and, moreover, should the 
tow-line break the net is saved by the second line from being 
lost. 
It will be found that the length of the towing-line must be 
regulated in some degree by the size of the net and the rate 
of sailing; if too short, the net will only touch and dance 
upon its surface without taking up the water ; if too long, it 
may be carried under water, and so increase the strain as to 
endanger the line or spar. The length should be sufficient to 
allow the mouth to keep dipping in and taking up water when 
the vessel is going at great speed ; but when a slower rate is 
to be adjusted for, then the mouth should keep at the surface, 
the grummet being generally nearly under water, but the 
waves of the sea Avili interfere with any great nicety in this 
respect. The line sliould be stron,2: eiio(i;>;h for any sudden 
jerk that might occur ^ 
