the spiral angle of graduated circle was rough estimated by measuring the addendum circle diameter and modified on milling machine.
测量齿顶圆直径估算分度圆螺旋角,用分度头在铣床上修正分度圆螺旋角,并进行误差分析。
it is one of the prerequisites for the accurate determination of the declination to study the graduated circle all-sidedly and carefully so as to improve the accuracy of the circle reading.
全面仔细地研究度盘,提高度盘读数的精度,是精确测定赤纬的前提之一。
both the graduated circle and vernier are equipped with fine adjusting screws and locking device so as to achieve fine adjustment.