• Webster's Revised Unabridged Dictionary
    • Midfeather (Mining) A support for the center of a tunnel.
    • Midfeather (Steam Boilers) A vertical water space in a fire box or combustion chamber.
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Century Dictionary and Cyclopedia
    • n midfeather A hollow horizontal septum in the furnace of a steam-boiler, which, being filled with water, forms a sort of water-bridge, under and over which the flame of the fuel is caused to pass. The midfeather thus adds a very effective heating surface, while retaining the incandescent gases and rendering their combustion more complete before they pass into the cooler fiues or tubes of the boiler.
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