590 Wisconsin Academy of Sciences , Arts , and Letters. 
The thermometer is guided and supported in the case by- 
two hollow brass cylinders which are lined with rubber 
tubing to prevent the thermometer from coming in contact 
with the metal. (Fig. 8, C.) This cylinder has a small rim 
on the inside at one end which prevents the rubber from 
passing entirely through it. The diameter of this cylinder 
is such that it will move freely inside the brass tube, or 2.2 
cm. in the case described above, and its length is 1.5 cm. The 
opening of the rubber tubing in the lower cylinder is just 
large enough to let the bulb of the thermometer pass through, 
but it will not pass beyond the constriction in the glass tube 
surrounding the thermometer which is situated at the upper 
end of the mercury bulb. At the upper end the thermom¬ 
eter case passes far enough into the rubber lining of the cyl¬ 
inder to be held securely in place, but it does not pass en¬ 
tirely through it. These small cylinders rest upon coil- 
springs of brass wire at both the upper and the lower ends 
of the thermometer case. Sometimes the thermometer ro¬ 
tates to one side a little which makes it difficult to read the 
scale. This rotation is prevented by a wire soldered inside 
the tubing which fits into a groove in the small brass cyl¬ 
inder. 
In order to prevent the messenger from striking the ther¬ 
mometer case, a bumper consisting of two rubber stoppers is 
placed on the line just above the releasing jaws. The mes¬ 
senger is stopped by a knot in the line a few centimeters 
below the jaws. 
THE ANCHOR RELEASE. 
The anchor release is a modification of the net release. 
(See fig. 9 and Plate XXXVIII, fig. 2.) It consists of three 
parts, an outer cylindrical piece, a plunger, and a spring. The 
outer par t is 3.8 cm. in diameter and 10.5 cm. long. It bears pro¬ 
jections on either side and these projections are separated 
into pairs by a slit 7 mm. wide which extends down from 
the top of the cylinder a distance of 8.3 cm. The cylinder is 
hollow, the opening being slightly more than 2.5 cm. in 
diameter, and extending to within 5 mm. of the lower end. 
The hole in this bottom part is just large enough to accom¬ 
modate the rope on which it is to be used. 
