The main use of Abney level in survey is to determine the

The main use of an Abney level in survey is to determine the angle of inclination. An Abney level is a surveying instrument used to measure slopes, angles of inclination, and vertical angles. It consists of a sighting tube, a spirit level, and a graduated scale. To use the Abney level, the surveyor points the sighting tube towards the object whose angle of inclination needs to be measured. Then, they adjust the instrument until the spirit level shows that the instrument is level, and the graduated scale can be used to read the angle of inclination. Therefore, the main use of an Abney level in surveying is to determine the angle of inclination of an object, which is a critical measurement in engineering and construction projects.