A Method for Testing and Measuring the Flexure of the Tube of the Low-Latitude Meridian Circle

In this article we propose a method of determining changes in the line of sight of the telescope caused by the factors,such as the flexure of the tube,the gravitational displacement of the main mirror,etc.,by utilizing an advantageous condition that the horizontal axis of a low-latitude meridian circle be turned at 180°in the course of observations.It is helpful to use this method to improve the accuracy of determing right ascensions.