Gnomonic

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Gnomonic \Gno*mon"ic\, Gnomonical \Gno*mon"ic*al\, a. [L.
     gnomonicus, Gr. ?: cf. F. gnomonique. See {Gnomon}.]
     Of or pertaining to the gnomon, or the art of dialing.
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     {Gnomonic projection}, a projection of the circles of the


        sphere, in which the point of sight is taken at the center
        of the sphere, and the principal plane is tangent to the
        surface of the sphere. "The gnomonic projection derives
        its name from the connection between the methods of
        describing it and those for the construction of a gnomon
        or dial." --Cyc. of Arts & Sciences.
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From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Projection \Pro*jec"tion\, n. [L. projectio: cf. F. projection.]
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     1. The act of throwing or shooting forward.
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     2. A jutting out; also, a part jutting out, as of a building;
        an extension beyond something else.
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     3. The act of scheming or planning; also, that which is
        planned; contrivance; design; plan. --Davenant.
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     4. (Persp.) The representation of something; delineation;
        plan; especially, the representation of any object on a
        perspective plane, or such a delineation as would result
        were the chief points of the object thrown forward upon
        the plane, each in the direction of a line drawn through
        it from a given point of sight, or central point; as, the
        projection of a sphere. The several kinds of projection
        differ according to the assumed point of sight and plane
        of projection in each.
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     5. (Geog.) Any method of representing the surface of the
        earth upon a plane.
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     {Conical projection}, a mode of representing the sphere, the
        spherical surface being projected upon the surface of a
        cone tangent to the sphere, the point of sight being at
        the center of the sphere.
  
     {Cylindric projection}, a mode of representing the sphere,
        the spherical surface being projected upon the surface of
        a cylinder touching the sphere, the point of sight being
        at the center of the sphere.
  
     {Globular}, {Gnomonic}, {Orthographic}, {projection},etc. See
        under {Globular}, {Gnomonic}, etc.
  
     {Mercator's projection}, a mode of representing the sphere in
        which the meridians are drawn parallel to each other, and
        the parallels of latitude are straight lines whose
        distance from each other increases with their distance
        from the equator, so that at all places the degrees of
        latitude and longitude have to each other the same ratio
        as on the sphere itself.
  
     {Oblique projection}, a projection made by parallel lines
        drawn from every point of a figure and meeting the plane
        of projection obliquely.
  
     {Polar projection}, a projection of the sphere in which the
        point of sight is at the center, and the plane of
        projection passes through one of the polar circles.
  
     {Powder of projection} (Alchemy.), a certain powder cast into
        a crucible or other vessel containing prepared metal or
        other matter which is to be thereby transmuted into gold.
        
  
     {Projection of a point on a plane} (Descriptive Geom.), the
        foot of a perpendicular to the plane drawn through the
        point.
  
     {Projection of a straight line of a plane}, the straight line
        of the plane connecting the feet of the perpendiculars let
        fall from the extremities of the given line.
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     Syn: See {Protuberance}.
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