|
This type of sundial was discovered by the German mathematician Hugo Michnik in 1922. The bifilar sundial 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. ==History== The original discovery was made and published in April 1922 by the mathematician and maths teacher, Hugo Michnik, from Beuthen, Upper Silesia. He studied the horizontal dial- starting on a conventional XYZ cartesian framework and building up a general projection which he states was an exceptional case of a Steiner transformation. He related the trace of the sun to conic sections and the angle on the dial-plate to the hour angle and the calculation of local apparent time, using conventional hours and the historic Italian and Babylonian hours. He refers in the paper, to a previous publication on the theory of sundials in 1914.〔Beiträge zur Theorie der Sonnenuhren, Leipzig, 1914〕 His method has been applied to vertical near-declinant dials, and a more general declining-reclining dial. Work has been subsequently done by Dominique Collin. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bifilar sundial」の詳細全文を読む スポンサード リンク
|