592 Wisconsin Academy of Sciences, Arts, and Letters . 
other jaw. When the anchor is to be released the anchor 
line is hauled in until it becomes taut; then a messenger is 
sent down the line which trips the release and leaves only 
the rope and release to be hauled in. 
The dimensions given are those of the first release of this 
type that was made. Experience has demonstrated that it is 
larger and heavier than necessary and a release about two- 
thirds or three-quarters as large would serve just as well for 
anchors weighing up to 35 kg. This release has been found 
very useful in lakes having a depth of 50 m. or more. A rock 
serves admirably for an anchor, and when this is abandoned, 
the only loss is the bit of line that is used to fasten it to the 
release. 
MESSENGER. 
Occasionally while making limnological observations it is 
convenient to have a messenger that may be put on or taken 
off the line at any point. Such a messenger is shown in Plate 
XXXVIII, fig. 4. The two halves areheld togetheronone side 
by pins which serve as hinges. The heads of these pins are sunk 
into one side of the messenger so that it will open. On the 
opposite side, two short pins fit into two holes on the other 
half when the messenger is closed. A cylindrical clamp made 
of sheet brass keeps the messenger closed. A small loop of 
brass wire is soldered to the upper end of one half of the 
messenger. This serves for the attachment of a piece of 
line. When the closing net is being hauled in hand over 
hand, the loose end of this string is held between the teeth 
so that the messenger can be released quickly when the net 
has been raised to the desired point. These messengers are 
made of brass, and are about 2.5 cm. in diameter by 5.5 
cm. long. 
