Chilled mirror digital dew point tester is inserted by drilling holes for accessing moisture content of concrete. This tester is the most commonly accepted instrument for measuring dew points of natural gas streams at field sites. It is sometimes used to resolve custody transfer disputes over natural gas quality. The dew point is visually identified and the chilled mirror is considered as a subjective instrument. An ideal dew point instrument would rely on objectively measured properties of the gas flow such as density, optical absorption, or temperature changes with pressure drop to identify the dew point.