552 
Wisconsin Academy of Scie?ices, Arts, and Letters. 
Fig. 1. 
Explanation of Plates 
PLATE XXXIX 
Top and bottom of the black bulb thermometer. At the top is 
the reading telescope in its holder. This is screwed upon the 
top of the tube, and the telescope is fastened in it by a ring 
of cork so that it can be moved slightly and pointed directly at 
the end of the advancing mercury. At the bottom the tube 
is screwed into the plate of the holder for the thermometer. 
The tube is 6 cm. in diameter and is composed of pieces each 
85 cm. long, which can be screwed together with water-tight 
joints. The instrument has been used to depths of 5 m. 
Fig. 2. 
Black Bulb thermometer in its frame, seen from above. The 
frame is 64 cm. long, 10.5 cm. wide. A is the cover for the 
bulb. The strings for sliding it back and forth can be seen. 
B is the plate to which the tube is attached. It is movable 
on the frame so that it can be fastened above the point indi¬ 
cating the temperature of the water. The tube is screwed 
into the plate above the glass seen in its center. 
Fig. 3. 
Receiver of the pyrlimnometer with the thermal couples covered. 
The figure shows the way in which the receiver is suspended 
and also the attachment of the lines which operate the 
shutter. 
Fig. 4. 
Receiver of pyrlimnometer, photographed from above. 
Fig. 5. 
PLATE XL 
• The receiver of the pyrlimnometer with the shutter open. The 
frame is about 46 cm. long, 16 cm. wide. The rack and pinion 
for operating the shutter can be seen, as also the two spirit 
levels for adjusting the position of the receiver.. 
Fig. 6. 
Water bottle, open. 
Fig. 7. 
Water bottle, closed. In the figure is seen the messenger, which 
has set loose the upper stopper. This, as it falls, carries 
down the bottle, and both parts fall upon the lower stopper. 
Fig. 8. 
Ekman dredge with jaws open. 
Fig. 9. 
Ekman dredge with jaws closed. The messenger which releases 
the jaws is seen on the line. 
