Infiltration gallery

Infiltration \In`fil*tra"tion\, n. [Cf. F. infiltration.]
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   1. The act or process of infiltrating, as of water into a
      porous substance, of a fluid into the cells of an organ or
      part of the body, or of persons into a hostile
      organization.
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   2. The substance which has entered the pores or cavities of a
      body. --Addison.
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            Calcareous infiltrations filling the cavities.
                                                  --Kirwan.
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   {Fatty infiltration}. (Med.) See under {Fatty}.

   {Infiltration gallery}, a filter gallery.
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Filter \Fil"ter\, n. [F. filtre, the same word as feutre felt,
   LL. filtrum, feltrum, felt, fulled wool, this being used for
   straining liquors. See {Feuter}.]
   Any porous substance, as cloth, paper, sand, or charcoal,
   through which water or other liquid may passed to cleanse it
   from the solid or impure matter held in suspension; a chamber
   or device containing such substance; a strainer; also, a
   similar device for purifying air.
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   {Filter bed}, a pond, the bottom of which is a filter
      composed of sand gravel.

   {Filter gallery}, an underground gallery or tunnel, alongside
      of a stream, to collect the water that filters through the
      intervening sand and gravel; -- called also {infiltration
      gallery}.
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