SFR 106 Lecture Notes - Lecture 1: Compass Rose, Zheng He, Lake Superior
19 Dec 2016
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Document Summary
A compass is an instrument containing a freely suspended magnetic element which displays the direction of the horizontal component of the earth"s magnetic field at the point of observation. Developed around 221 206 b. c. in china. Lodestone was the mineral first used, composed of iron oxide. The chinese used it as a fortune telling gimmick at first. Iron oxide aligns its bearing north to south. Magnetized needles were introduced in the 8th century. The needles were made of iron oxide. Lodestones and spoons were replaced by a four-point square illustrating north, east, The first person recorded to have used the compass as a navigational aid was zheng he (1371-1435), from the yunnan province in china, who made seven ocean voyages between 1405 and 1433. Compass rose is a depiction of orientation and direction that is placed on compasses, maps, and charts. Thirty-two points are depicted around a circle in equal intervals, marking the four cardinal directions (n, e, s, w),
