[1629]. Equilibrium valve.

[1630]. Equilibrium valve, not steam tight, but serrated, to cut off gradually, employed for governors of steam engines.

[1631]. Equilibrium cylindrical grating valve, may be used to open and close either by vertical or revolving motion.

[1632]. Common throttle or butterfly valve.

[1633]. Duplex throttle or damper for a three-way pipe or flue.

[Larger plate.]

[1634]. Hydraulic high-pressure check valve, with long guide wings.

[1635]. Hydraulic plug or spindle valve and seating; all seatings for high pressure should be narrow and hard.

[1636]. Duplex or Ramsbottom safety valve; each valve serves as a fulcrum by which to lift the other. One fulcrum point should be jointed to the lever and the latter move in a vertical guide, or else the point of attachment of the spring to the lever be placed below the level of the valve seatings.