Experimental Techniques for Levels of High Precision Using the Zeiss Ni2 Automatic Level

摘要

Instrumentation and Techniques developed by the U. S. Lake Survey for levels of high precision are described. Automatic, or 'self-leveling' Zeiss Ni2 instrument is used with plane-parallel plate micrometer. Special techniques are used to compensate for systematic errors unique to automatic levels. Levels can be run with these methods to a tolerance of 1.5 millimeters times the square root of the length of the section in kilometers. (Author)