page_title: Bifilar sundial
hierarchical_section_title: Bifilar sundial
caption_attribution_description: cadran bifilaire
context_page_description: A bifilar dial is a type of sundial invented by the German mathematician Hugo Michnik in 1922. It has two non-touching threads parallel to the dial. Usually the second thread is orthogonal- to the first.
  The intersection of the two threads' shadows gives the local apparent time.
  When the threads have the correctly calculated separation, the hour-lines on the horizontal surface are uniformly drawn. The angle between successive hour-lines is constant. The hour-lines for successive hours are 15 degrees apart.
context_section_description: A bifilar dial is a type of sundial invented by the German mathematician Hugo Michnik in 1922. It has two non-touching threads parallel to the dial.  Usually the second thread is orthogonal-(perpendicular) to the first.
  
  The intersection of the two threads' shadows gives the local apparent time.
  When the threads have the correctly calculated separation, the hour-lines on the horizontal surface are uniformly drawn. The angle between successive hour-lines is constant. The hour-lines for successive hours are 15 degrees apart.
caption: A bifilar dial showing the two wires
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