from The Century Dictionary and Cyclopedia
- n. A valve for controlling water.
- n. Specifically, the feed-valve controlling entry of feed-water into a boiler.
- n. A relief-valve, or cylinder-cock, or automatic snifting-valve, designed to let out water from the cylinder of a steam-engine.
Sorry, no etymologies found.
While formerly the air in the space next the zinc wall was either cooled or heated alternately by opening the water-valve or by passing a current through the heating coil, at present it is found much more advantageous to allow a slow flow of air and water through the pipes continuously, thus having the air-space normally somewhat cooler than is desired.
As soon as the water-valve was closed and the air-cock opened, the compressed air blew all of the water out of the tube.