An Autocollimation Method of Measuring the Level Error of the Horizontal Axis of A Meridian Instrument

A new method is proposed to replace the common level tube measuring method which is effected by many factors.By means of this new method one can mensure the true level error of the liorizontal axis,wliich can be turned at 180°when observation are carried out,using the mereary plane as the datum plane and the autocollimation mode.The attainalilc accuracy of measurement is also estimated.