36 NATURALISTS’ ASSISTANT. 
cover, so that it will not catch and tear on rocks, etc., on the 
bcttom. Iron handles are attached to the frame, and to one 
of these the dredge rope is tied ; the other handle is made 
fast to the rope by means of a bit of “spun yarn” or lighter 
cord, as shown in fig. 13. The object of this is that, if the 
dredge be caught on a rock, the smaller cord will break and 
the dredge free itself. A weight should be attached to the . 
rope a short distance 
(six to twelve feet). in 
front of the dredge, so 
that its mouth may be 
kept on the bottom. The 
length of rope paid out 
should be about twice 
the depth of the water 
in which the dredging is 
conducted. In dredging 
from a sail-boat it is best, 
if possible, to take ad- 
vantage of the currents. 
Put the dredge over the 
bows, taking care that it 
Fic. 13. 
does not turn inside out 
or foul while going down, then let the boat drift as though 
she were dragging an anchor. Where currents are not strong 
enough the boat head should be turned toward the wind, so 
that it will just move through the water, and then put the 
dredge over the windward side near the stern. The boat will 
then drift slowly, drawing the dredge over the bottom. 
