According to the reference network, the references of the second-class level are the papers of Liu Chenglong, Yang Xuefeng and Zhang Yuechuan. This paper discusses the application of second-class leveling instrument, measurement quality control and the feasibility of replacing second-class leveling instrument with cross-sea leveling instrument, which provides some references for the design, improvement and improvement of second-class leveling instrument.
Second-class leveling, that is, precision leveling. Leveling, also known as "geometric leveling", is a method of measuring the height difference between two points on the ground with a level and a leveling ruler. Place a level between two points on the ground, observe the level ruler erected on the two points, and calculate the height difference between the two points according to the reading on the ruler.