我们在坑下测量经纬仪导线水平角的时候,往往以为坑下测量与地面测量没有什么原则的区别,而忽视了关于经纬仪的归心误差对水平角测量精度的影响。坑内测量的特点之一是:导线边的长短有限,不能随测量人员的主观愿望而任意延长可缩短。特别是通过旧的生产巷道的导线测量,由于巷道弯弯曲曲,十几公尺就有一个拐弯;在转车场布置导线有时要短到五、六公尺。但是遇到地质情况正常的巷道,测量视线还可直接通视二、三百公尺。这样,在导线长短不一,和许多边很短的情况下,欲想通过这些巷道进行导线测量做为长距离的井巷贯通时,往往是达不到设 When we measure the horizontal angle of the theodolite conductor under the pit, we often think that there is no principle difference between the pit measurement and the ground measurement, and the influence of the centering error of the theodolite on the measurement accuracy of the horizontal angle is neglected. One of the features of pit measurement is that the length of the wire edge is limited and can not be arbitrarily lengthened with the subjective desire of the surveyor. In particular, measurements taken from the wires of the old production laneways have a turn on the tens of meters due to the winding roadways; wires sometimes are as short as five to six meters on the turnaround floor. However, the normal geological conditions of the roadway encountered, measuring the line of sight can also be directly read two or three hundred meters. In this way, in the wire length, and many of the short side, in order to pass these roadway wire measurement as a long distance through the shaft, often can not reach the set