Bull. U. S, (■- C. 1856. (To face page 293.) 
Plate XV. 
m 
L 
Upper Vcj/i/e Seat- 
3 1 
\i 
J^orrer T^/i/e Seat. 
\m 
/AtCH£S. 1 
THE BELKNAP SOUNDING CYLINDER. NO. 2. 
a. (’yliiider, brass. 
h. Castings, brass. 
c. Screw couuertioii of cylinder to casting. 
d. U])per valve seat. 
e. Lower valve seat. 
/. tipper valve. 
g. Lower valve. 
ti. Poppet valve. 
l\ Si»iral spring. 
1. Shoulder holding lower valve seat down. 
?/?.. Kod, iron. 
n. Detacher, iron. 
0 . Swivel ring, iron. 
%). Screw tamuection of rod to casting. 
q. Stud, brass. 
