六分仪(sextant),在测绘和船舶通信导航中,是由分度弧、指标臂、指标镜、水平镜、望远镜和测微鼓组成,弧长约为圆周的六分之一,用以观察天体高度和目标的水平角与垂直角的反射镜类型的手持测角仪器。广泛用于航海和航空中,用来确定观测者的自身位置。
历史
六分仪的原理由伊萨克·牛顿提出,1732年,英国海军开始将原始仪器安装在船艇上,因为当时最大测量角度是45度,因此被称为八分仪。1757年,约翰·坎贝尔船长将八分仪的测量夹角提高到60度,发展成为六分仪。
参考文献
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