TABLE OF CONTENTS Line graduated geometric bodies, with graduation spacings representing known distances, are the bases for all direct measurements of specific distances. It follows that instruments having line graduated elements as integral members may be considered the only mechanical means capable of carrying out direct measurements without the assistance of complementary equipment or processes. However, because of their long standing use in industry, and convenient portability, electronic design advances and data collection methods have been applied to a modern class of these traditional instruments.
The essential property of instruments with line graduated elements is their capability to measure any distance within their capacity range. This distinction of line graduated instruments is valid independently of the achievable sensitivity or accuracy of the measurement.
The sensitivity of the measurement will depend primarily on the instrument's basic design. This is most obviously displayed, although not necessarily truthfully represented, by the least distance between the individual graduations of the basic gage element and of the supplementary readout device, when the readout device is part of the instrument.
Factors affecting the measuring accuracy of a line graduated instrument are the original accuracy of the graduation, the level of resolution of the graduation lines and of the readout members, the instrument's design and the general workmanship exercised in its manufacture. The precision of measurements made with line graduated instruments will also be a function of how truly the actual distances to be measured are associated with the corresponding instrument graduations.
Conditions related to instrument accuracy...
