You now have a number of lines that cross each other on the composite psychrometric chart. If you plot a point on a constant dry-bulb line, that point will correspond to different values on the constant lines for wet-bulb temperature, dew point, relative humidity, specific volume, and enthalpy. Since any two of these constant lines cross at only one point on the chart, you can plot this point exactly if you know any two properties of the air. From this point, you can then move along respective constant lines to find other properties of the air. Once you learn how to use a psychrometric chart, obtaining the values you need by reading them from their respective scales is not as difficult as it looks.