574 Wisconsin Academy of Sciences , Arts, and Letters . 
plunger, and is spanned by two loops of brass wire which 
project outward far enough to permit the passage of this 
arm. These loops of wire curve downward in order to facili¬ 
tate the release of the ring that supports the top of the net. 
At another point in the upper half of the outside cylinder is 
another slot 1.5 cm. long, through which a screw passes to 
the plunger. This screw holds the plunger in place. The 
Fig. 3.—Release for closing net. 
plunger is a brass cylinder a little less than 1.6 cm. in di¬ 
ameter and 4.2 cm. long. The upper 4 mm. has a diameter 
of 1.9 cm. and this flange prevents the messenger from driving 
the plunger entirely within the outer cylinder. The plunger 
is pierced by a hole just large enough for a rope. Near the 
bottom on one side, it possesses an arm which projects out¬ 
ward about 1 cm., and then upward about 1.5 cm. The 
plunger is actuated by a coil spring of brass wire which rests 
on the inner rim at the lower end of the outer cylinder. This 
arm passes through the wire loops on the outer cylinder and 
