Measuring the Precision of a Level

Differential leveling procedures, as well as an awareness of sources of error in the level rod, the observer, and the atmosphere are involved in determining the reasonable accuracy to be expected in the use of the level. For the levels to be compared successfully, the field work for each level must be performed on the same test arrangement and under relatively the same atmospheric conditions. Study of the level, the order of accuracy, the length of the line of sight, and the percentage of successful level section closures. The nomogram allows the rapid selection of a desirable length of sight for a specific order of accuracy and percentage rerun given the quality of the level to be used. Limitations in the application of the results are mentioned.