Improvements in instruments for calculating variations in the altitude of the sun

摘要

584,532. Calculating - apparatus. DAHLBERG, O. Sept. 19, 1944, No. 17900. [Class 106 (i)] An instrument for calculating the altitude of the sun at various latitudes on various dates comprises a disc 2 provided with latitude scales 5, 6 and date indicators 9, 10, the disc being rotatable on a base plate having sunaltitude scales 7, 8, date scales 11, 12 and lines 13 representing the sun's direction. An arm 3 is rotatable about the centre of the disc 2 and carries a protractor-like scale 4 at its end. The disc 2 is set so that the dateindicator 9 or 10 shows the date on the scale 11 or 12 and the arm 3 is adjusted to.the latitude on the scale 5, 6. The altitude of the sun is the angle between the base line (horizontal plane) of the protractor 4 and the protractor radius extending parallel with the sun-direction lines 13, this angle being read on the protractor.