JPS56107114A - North-south indicator - Google Patents

Abstract

PURPOSE:To find the exact north-south direction by a method wherein scale divisions at nearly equal intervals are provided on the main body of an instrument by using the principle of a sundial of a horizontal type, the tilt of the main body of the instrument is adjusted in accordance with the latitude of a given place, and a time indicated by a projecting body based on sunrays is made to accord with a correct time. CONSTITUTION:A point A determined by a line OB equaling 8cm and being perpendicular to a line O out of the shadows -VI of the projecting body positioned at a point 0 formed at noon to 6:00p.m. and by a line BA equaling 4cm and being perpendicular to the line OB is taken, a circle is drawn with the radius of AM equaling to 18cm, and the intersecting points of the circumference of the circle with the lines indicating 1:00p.m. to 6:00p.m. are determined to be C-L. Under the condition, angles theta12-theta6 are found to be at nearly equal intervals and thus the sundial at the latitude of 45 deg. is obtained. Scale divisions for 6:00-12:00a.m. are obtained in the same way. At a point of place whose latitude is psi, aforesaid divisions 6 are provided on a supporting plate 7 titled at an angle of 45 deg.-psi to the horizontality. A square projecting plate 1 having sides equal in length to a distance between two points of the position O, O' at noon is fitted, with a tilt of 45 deg., to the central position of a segment 5 connecting points at 6:00a.m. and p.m. The right and left sides 2 and 3 of the plate indicate the direction of the North Pole and thereby the north-south direction is found correctly.