Bull. U. S. r. C. 1806. (To face page 326.) 
Plate XXI. 
THE TANNER IMPROVED THERMOMETER CASE AND SIGSBEE CLAMP, USED WITH THE NEGRETTI & ZAMBRA DEEP-SEA THERMOMETER 
Nomoiclaturv. 
a. Neck of the bulb. 
b. Catch reservoir. 
c. Small receptacle. 
(/. Partition confniiiig mercury in 
shield surrounding bulb. 
e. Glass shield inclosing thermom- 
eter. 
/. Thermometer case. 
g. Thimble ^’^il]l rubber lining. 
h. Spiral springs. 
i. Cap. 
j. Pivot. 
k. Slot for reading scale. 
l. Frame of cast brass. 
m. Guard. 
n. Propeller. 
0 . Sj)iiidle. 
p. Set screw. 
g. SigslM‘6 claiu]). 
r. Clamp screw. 
